IMAP vs. POP

What do they stand for?

IMAP

Internet Message Access Protocol

POP

Post Office Protocol

What's the difference?

The main difference, as far as we are concerned here, is the way in which IMAP or POP controls your e-mail inbox.
When you use IMAP you are accessing your inbox on the U of M's central mail server. IMAP does not actually move messages onto your computer. You can think of an e-mail program using IMAP as a window to your messages on the server. Although the messages appear on your computer while you work with them, they remain on the central mail server.
POP does the opposite. Instead of just showing you what is in your inbox on the U's mail server, it checks the server for new messages, downloads all the new messages in your inbox onto your computer, and then deletes them from the server. This means that every time you use POP to view your new messages, they are no longer on the central mail server. Figure 1 illustrates these concepts.

IMAP	POP
Figure 1: Accessing your inbox, IMAP versus POP.

IMAP makes it easier to view mail from home, work, and other locations

Because IMAP leaves all of your messages on the central mail server, you can view these messages from any location with Internet access. This means the U of M e-mail inbox you view from home will be the same one you see at work.
Since POP downloads new messages to your computer and removes them from the server, you will not be able to see those new messages on another computer when you check your inbox. Those messages exist only on the computer that downloaded them using POP.
However, if you use IMAP and create e-mail folders on the server, these folders are accessible from anywhere you read your e-mail using IMAP. If you use POP and create e-mail folders, they are stored locally, and you cannot access these folders from anywhere except the computer on which you created them.
POP can create problems if you alternate between it and IMAP. There is an option in many POP e-mail programs to leave copies of the messages on the server, but this option has complications. When you leave copies of the messages on the server, then access your e-mail using WebMail or another IMAP e-mail client, the POP client may create duplicate messages next time it accesses the inbox; you will see each of the messages more than once, and you will have to clean out (delete) the unwanted ones.

You may want to keep local copies

While using IMAP to save e-mail on the central mail server is recommended, there are reasons to have local copies of messages (messages downloaded to the computer, as with POP). Fortuanately, IMAP allows you to keep local copies of all your messages. The option of local copies is useful when you are connecting from a dial-up connection. You may want to download your messages, then disconnect from the Internet and work with your mail offline. Please note that while you are working offline, you cannot send or receive mail. You need to be connected to the Internet to do those tasks.

You have a backup of your e-mail with IMAP

The University's central e-mail servers are backed up every night. Thus, when your e-mail is stored on the U's e-mail server (as is the case with IMAP), a backup of your e-mail is made every night. These backups are used in the event of system failures or if a virus deletes your local mail. If you use POP, you lose your mail. The University cannot help you recover it because it was not stored the U's central e-mail server.
With the growing number of computer viruses and attacks from hackers, there is a greater possibility that e-mail can be deleted without your knowledge. The best insurance against loss of important e-mail is to have it on the University's e-mail server.

How To Configure GMail Account With Microsoft Outlook 2010

Microsoft Outlook is the most powerful and intuitive e-mail client software. Microsoft’s Outlook 2010 provides  a very rich set of e-mail management tools to help you better manage your emails with a cool user interface. If you have a GMail account, then configuring the account with Microsoft Outlook 2010 is a piece-of-cake.

First of all launch MS Outlook 2010 and click the office button which is located in the left most corner, now under the Info category you will be able to see the Account Settings option, click the drop down button and choose Add Account as shown in following screenshot.

In the next step, select Email Account, enter Your Name, Email Address, and Password and click Next.

Now sit back and relax, Outlook 2010 will do the rest for you, it will establish connection to the relevant network, search for GMail server settings and log you on to the server automatically.

It will take a couple of minutes to complete the required configuration.

Click Finish and thats all, it will take some time to download your emails.

Now use all the enhanced features of Outlook 2010 to manage your GMail inbox. Enjoy!

How to configure gmail account on outlook 2007

Step1: Configure Gmail Account

• First Log into your gmail account.
• Left-click "Settings" in the upper right corner of the gmail page.
• In "Settings," click the "Forwarding and POP/IMAP" tab.
• Locate the "IMAP Access" section. Click the "Enable IMAP" radio button.
• Click "Save Changes." Your gmail account is now ready to be configured in Outlook 2007.

Step2 : Configure outlook 2007

• In Outlook 2007, click "Tools" on the main toolbar. In the drop-down menu, Click "Account Settings." In the account settings dialog box, the "Email" tab is selected by default.
• With the "Email" tab selected, click "New." The "Add New E-mail Account" dialog box will appear. In the form provided, enter your name, email address and password. Click the box next to "Manually configure server settings or additional server types," then click "Next."
• In the "Choose E-mail Service" dialog box, click the radio button next to "Internet E-Mail." Click "Next" to progress to the "Internet E-mail Settings" option.
• In the "Server Information" section, click the arrow next to account type and select IMAP. In the "Incoming Mail Server" box type "imap.gmail.com". In the "Outgoing Mail Server" box type "smtp.gmail.com".
• In the "Logon Information" section, insert your full Gmail address in the "User Name" box. It should resemble "username@gmail.com." Insert your password in the "Password" box. Click the check box for "Remember Password," then lick "More Settings."
• Click the "Advanced" tab. Change the "Incoming server (IMAP)" to "993" and select "SSL" from the drop-down menu. Set "Outgoing server (SMTP)" to "587" and select "TSL" from the drop-down menu.
• Click the "Outgoing Server" tab. Click the check box and enable "My outgoing server (SMTP) requires authentication." Leave the radio button on "Use same settings as my incoming mail server." Click "OK."
• On the "Internet E-mail Settings" dialog box, click "Next," then "Finish."
• On the "Account Settings" dialog box, you will see your new Gmail account. Click "Close." If asked, you can instruct Outlook to synchronize your folders, or you can manually select "Send/Receive" on the top toolbar.

How to remove rememberd password in shearing server on window

This command is useful to remove the add user and their password on any shearing server(samba). Using this command you can also add user and user password on any shearing server.
rundll32.exe keymgr.dll, KRShowKeyMgr
copy this command and past on command prompt.

Security cameras and multimedia streaming are affecting your network

There was a time when security cameras were hardwired back to a central location with lots of screens. Here people sat and watched and made sure that tapes of footage were changed and properly stored. In today's world, these devices are now IP-based and share computer networks with everything else.
I was visiting one of the largest football stadiums in Europe a few weeks back. The network manager gave me a very interesting tour, which focused on the IT infrastructure. Systems such as security cameras, crowd control monitoring, public announcement systems and the large screens around the arena are all now connected to a shared computer network.  This gives greater flexibility when deploying these systems as you don't need to run separate cables. However, it does create challenges for the IT manager as this data is now carried on their network.
This type of network traffic is not limited to places like arenas with lots of TV screens. While reviewing traffic rates on a university network recently, I found that over 75% of all traffic was associated with IP-based security cameras. They had a flat network with a single VLAN so it was becoming a big problem.
If you want to check for this activity on your network, I suggest you should be familiar with layers 2 and 3 of the OSI model. Over on the EtherGeek blog, Josh Stephens has some useful information on understanding layer 2 of the OSI model and understanding layer 3 of the OSI model.
In most cases, systems which generate audio or video outputs will stream this data onto a network using one of these methods.

• Multicast traffic. IP multicast is typically used for sending IP datagram's to a group of interested receivers in a single transmission
• User Datagram Protocol (UDP) traffic with specific source and destination IP addresses.

For those of you considering rolling out systems like IP-based security cameras or multimedia screens which get updates from the network, I would recommend that you create a specific VLAN for this traffic. This will keep it separate from other business critical applications.
I would also suggest that you check for this activity on your network. You can either do a periodic audit or have a system in place that constantly checks your network. There are two things to watch out for:

1. Monitor traffic as it goes through the core of your network. You are looking for UDP activity. Normally applications which use TCP are the most active. If you find lots of UDP traffic, look at the source and destination IP addresses. If these are associated with media streaming then it could be time to consider moving this to a separate VLAN.
2. Check for multicast activity. If your traffic analysis system allows you to use filters, check for activity associated with the 224.0.0.0/4 network. This block of IP addresses has been reserved for multicast. If you also use IPv6, then you should also check for activity associated with the ff00::/8 prefix.  

Finally, IPTV services are also getting popular. An IPTV is a service through which Internet television is delivered to end-users. The number of global IPTV subscribers is expected to grow significantly over the next few years. I will also deal with this topic in more detail in an upcoming post. In the meantime, you should keep an eye on any unusual activity on your Internet gateway which is using lots of bandwidth over long time periods. This can be a sign of large downloads or constant streaming media coming into your network.

How to install squid on CentOS 5.5

Install Squid on CentOS / RHEL 5

$ yum install squid

Prompt:

Install ( x ) Package(s)

Total download size: ( x ) M

Is this ok [y/N]: Answer y then hit Enter Key

Installing: squid ######################### [1/1]

Installed: squid.i386 2.5.STABLE14

Complete!
Squid Basic Configuration

Squid configuration file located at /etc/squid/squid.conf. Open file using a text editor:

$ locate squid.conf
/etc/squid/squid.conf
$ pico /etc/squid/squid.conf

NEED TO CHANGE:

line 53 and 54
looks like this

#Default:
#http_port 3128

change to

#Default:
http_port 3128

//* or change 3128 to any unused port refer here to check commonly used port http://www.mysql-apache-php.com/ports.htm *//

line 1876

#acl our_networks src 192.168.1.0/24 192.168.2.0/24
#http_access allow our_networks

change to
acl our_networks src 192.168.1.0/24 192.168.2.0/24
http_access allow our_networks

Line 1880
#http_access allow localhost
#http_access deny all

to

http_access allow localhost
http_access allow [ your ip range here without the brackets ]
http_access deny all

$ chkconfig squid on
$ /etc/init.d/squid start

Output:
init_cache_dir /var/spool/squid… Starting squid: . [ OK ]

Verify port 3128 is open:

$ netstat -tulpn | grep 3128

Output:

tcp 0 0 0.0.0.0:3128 0.0.0.0:* LISTEN 20653/(squid)

Open TCP port 3128

Finally make sure iptables is allowing to access squid proxy server. Just open /etc/sysconfig/iptables file:

$ pico /etc/sysconfig/iptables(config)

Append configuration:

-A RH-Firewall-1-INPUT -m state –state NEW,ESTABLISHED,RELATED -m tcp -p tcp –dport 3128 -j ACCEPT

Restart iptables based firewall:

$ /etc/init.d/iptables restart

Output:

Flushing firewall rules: [ OK ]

Setting chains to policy ACCEPT: filter [ OK ]

Unloading iptables modules: [ OK ]

Applying iptables firewall rules: [ OK ]

Loading additional iptables modules: ip_conntrack_netbios_n [ OK ]

note if you have CSF firewall:

$ pico /etc/csf/csf.conf

# Allow incoming TCP ports
TCP_IN = “20,21,22,25,53,80,110,143,443,465,953,993,995,2077,2078,2082,2083,2087,[your squid proxy port here without the bracket]”
# Allow outgoing TCP ports
TCP_OUT = “20,21,22,25,37,43,53,80,110,113,443,587,873,953,2087,2089,2703,[your squid proxy port here without the bracket]”
# Allow incoming UDP ports
UDP_IN = “20,21,53,953?
# Allow outgoing UDP ports
# To allow outgoing traceroute add 33434:33523 to this list
UDP_OUT = “20,21,53,113,123,873,953,6277?

//Now restart the firewall!
$ csf -r

Note: if you install on Centos 5.3 you will have to open your port and save settings

/sbin/iptables -I RH-Firewall-1-INPUT 1 -p tcp --dport [PORT] -j ACCEPT

/etc/init.d/iptables save

Adobe Flash CS5,Adobe Photo Shope ,Illustrator, After Effect and Dream Viwer Keys and Serial Numbers

1302-1449-8604-6106-9463-6260 1302-1078-1879-9146-8907-5374
1302-1519-3643-2900-6750-5666 1302-1448-3032-7894-8268-4989

1330-1591-0512-8620-6165-9751                        1330-1610-5632-3862-8372-8763
1330-1078-1802-9115-0418-6411                        1330-1839-4491-5397-8087-5433
1330-1520-8918-6499-6052-3218                       1330-1653-8903-1836-3677-5917                   1330-1153-1612-4896-8932-8432                       1325-1118-5864-4422-1094-1166                     1325-1558-5864-4422-1094-1126                       1325-1958-5864-4422-1094-1178             1325-1085-0645-5332-7061-9771                       1330-1927-7762-6383-0202-0414

here the number started form 1325 are the master key of cs5

1034-1767-5589-5174-3399-3968          1034-1176-1533-7104-2854-1573
1034-1624-6521-6601-7422-4512  1034-1348-5797-5076-8257-7252

1034-1006-5290-0019-3090-0219 

 

1325-1243-2842-5475-9398-1623                        1325-1041-2027-0987-8293-5644
1325-1340-7176-1506-1967-7195                        1023-1631-3275-3276-0087-5426

 1192-1927-7762-6383-0202-0474

 

Hotspot in WiFi Network

A hotspot is any location where Wi-Fi network access (usually Internet access) is made publicly available. You can often find hotspots in airports, hotels, coffee shops, and other places where business people tend to congregate. Hotspots are considered a valuable productivity tool for business travelers and other frequent users of network services.Technically speaking, hotspots consist of one or several wireless access points installed inside buildngs and/or adjoining outdoor areas. These APs are typically networked to printers and/or a shared high-speed Internet connection. Some hotspots require special application software be installed on the Wi-Fi client, primarily for billing and security purposes, but others require no configuration other than knowledge of the network name (SSID).

TraceRoute command

Traceroute is a utility program that monitors the network path of test data sent to a remote computer. On Unix and Linux computers, the "traceroute" application is available in the shell, while on Windows computers, the "tracert" program can be accessed from DOS.Traceroute programs take the name or IP address of a remote computer on the command line. When run, traceroute sends a series test messages over the network (using ICMP) to each intermediate router progressing until the last message finally reaches its destination. When finished, traceroute displays the ordered list of routers that represent the path from that computer to the destination.

What is Apache Web Servers

Apache is generally recognized as the world's most popular Web server (HTTP server). Originally designed for Unix servers, the Apache Web server has been ported to Windows and other network operating systems (NOS). The name "Apache" derives from the word "patchy" that the Apache developers used to describe early versions of their software.The Apache Web server provides a full range of Web server features, including CGI, SSL, and virtual domains. Apache also supports plug-in modules for extensibility. Apache is reliable, free, and relatively easy to configure.Apache is free software distributed by the Apache Software Foundation. The Apache Software Foundation promotes various free and open source advanced Web technologies.
Following commands are usefull to install apache and phpmyadmin with
1.Installing Mysql:
yum install mysql mysql-server
chkconfig --levels 235 mysqld on
/etc/init.d/mysqld start
 mysqladmin -u root password servertest //this is the root and its password that you required when first time login in phpmyadmin here "root" is user and "servertest" is password
2.Installing Apache2:
yum install httpd
chkconfig --levels 235 httpd on
/etc/init.d/httpd start
3.Installing PHP5:
yum install php
/etc/init.d/httpd restart
4.Getting MysQl support in PHP5:
yum search php
yum install php php-mysql php-common php-gd php-mbstring php-mcrypt php-devel php-xml php-xmlrpc
/etc/init.d/httpd restart
5.Installing phpMyAdmin:
cd /var/www/html
wget http://sourceforge.net/projects/phpmyadmin/files/phpMyAdmin/2.11.11.1/phpMyAdmin-2.11.11.1-english.tar.gz
tar xvfz phpMyAdmin-2.11.11.1-english.tar.gz
mv phpMyAdmin-2.11.11.1-english phpmyadmin
cd phpmyadmin
cp config.sample.inc.php config.inc.php
nano config.inc.php
a file will open just type and replace,cookies,with,http,
service httpd restart

Cisco fastest router

Cisco launches super fast router.....

NETWORKING HARDWARE VENDOR Cisco announced a router that it thinks could change the world wide web for evermore.The company said its glorious CRS-3 carrier-grade router is designed to serve as the foundation of the next-generation Internet, as it can manage speeds of up to 322 Terabits per second.

Just so the great unwashed know, that is fast enough to transmit the entire printed collection of the US Library of Congress in one second, or the bandwidth required for every man, woman and child in China to make a video call, simultaneously. Every movie ever created could be streamed in less than four minutes, Cisco claims.

Of course it is just a router and not the entire world wide web infrastructure, but it has more than 12 times the traffic capacity of anything else out there.Cisco says that it will make Internet and cloud services much more efficient. It mentions that AT&T recently tested the Cisco CRS-3 during the world's first field trial of 100-Gigabit backbone network technology, which took place over AT&T's live network between New Orleans and Miami recently.

The CRS-3 machine will replace the firm's CRS-1 router, which is still one of the most popular and fastest available commercial routers. The CRS-3 is three times faster than the CRS-1.The firm says its latest top of the line carrier-grade router is powered by its Quantumflow Array Processor, which unifies the combined power of six communications processor chips to work as one. This apparently will deliver high service capabilities and processing power. It also will require only a fraction of the power.

Address Binding Technique 3

Address Resolution with message exchange: In this approach the computer that needs to resolve an address sends a message across network and receives reply.The message carries a request that specifies the protocol address,and the reply carries the corresponding hardware address.Now the main question that came in front of us is that where all these requests be sent.Generally there are two designs that are used for this.In the first design a network includes one or more servers that are assigned the task of answering address resolution requests.

Whenever,address resolution is needed a message must be sent to any of these servers which will send a reply.In the second design no special address resolution servers are needed.Instead,each computer on the network participates in address resolution by agreeing to answer resolution requests for its address.When a computer needs to resolve an address,it broadcasts a request on the network.All machine receive the request and examine the requested address.If an incoming request matches a computer’s address, the computer responds.Now discuss the advantages of both the designs.

The chief advantage of the first scheme arise from centralization because a few address resolution servers handle all resolution tasks on the network,address resolution is easier to configure,manage and control.Now the advantage of second design arise from distributed computation.Address resolution servers may be expensive.In addition to the expense of additional hardwares like extra memory.In addition to this servers are expensive to maintain because address binding information stored in servers must be updated whenever new computers are added to the network or hardware address changes.Furthermore ,address resolution servers can become a bottleneck on a large busy network.If each computer is able to resolve its own address ,then there is no need of servers.

Address Binding Technique 2

Address Resolution with closed form computation: As all we know that many network technologies use static physical addresses, some technologies use configurable addressing in which a network interface can be assigned a specific hardware address. For such type of networks it is possible that we can choose addresses that make closed form address resolution possible.A resolver that uses a closed form method computes a mathematical function that maps an IP address to its equivalent hardware address. If the relationship between the IP address and its coprresponding hardware address is straightforward, the computation requires only a few arithmetic operations.Infact,the host portion of a computer’s IP address can be chosen such that it is identical to the computer’s hardware address.

Let’s understand this situation with the help of a example, suppose a configurable network has been assigned the network address 220.123.152.xxx and its suffix ranging from 0-24. As computers are added to the network, each computer is assigned an IP address from this range and a matching hardware address.The first host is assigned an IP address 220.123.152.1 and hardware address 1. The second host is assigned an IP address 220.123.152.2 and hardware address 2. The suffixes need not be sequential, if a router attached to a network assigned IP address202.123.152.101,then the router is assigned an IP address of 121.Given the IP address of any computer on the network, the computer’s hardware address can be computed by a single Boolean ‘and’ operation.

Hardware Address=IP Address & 0xff

As I think it is clear from the example that why closed form resolution is often used with configurable networks.

Address Binding Technique 1

1.Address resolution with table lookup: This technique of address resolution requires a data structure that contains information about address binding. The table consists of an array. Each entry in the array contains a pair (P,H),where P is the protocol address and H is its corresponding hardware address. The main advantage of table lookup approach is generality- a table can store the address bindings for an arbitrary set of computers on a given network. In particular a particular protocol address can map to an arbitrary hardware address.

Furthermore, the table lookup algorithm is straight forward and easies among all the approaches. Suppose we have given a next-hop address, N, the software searches the table until it finds an entry where the IP address matches N. The software then extracts the hardware address from the entry.For a network that contains a less then dozen of hosts, a sequential search is sufficient ,the resolution software begins at first entry and searches each entry in table until a match is found. But for large networks this sequential search is not possible because it consumes excessive CPU time. In these type of situations to improve computational efficiency we can use Hashing or Direct Indexing.
As all we know that Hashing is a general purpose data structure and is well known to all the programmers, so, here I am not going to discuss it. Let’s take a look at the other technique that is of Direct Indexing. Direct Indexing is slightly more efficient but less general technique. In particular Direct Indexing is possible only in those cases where protocol addresses are assigned from a compact range.
For Example
Direct Indexing can be used with IP addresses that are arranged in sequential order. In these type of cases the software maintains a one dimensional array of hardware addresses, and uses the host suffix from an IP address as an index to an array.
In the next post I will tell you the second technique of Address Binding.

Address Resolution Protocol

As all we know that IP addresses are virtual because they are maintained by software. Neither Local Area network nor Wide Area Network hardware understands the relationship between an IP address prefix and a network or the relationship between an IP address suffix and a particular computer. I am telling you all these things because we have to know all these things before understanding Binding Address Protocol. Now let’s come to our main issue of Binding Protocol Addresses, the first point that came into the mind of any one that is new to networking is what Binding Protocol Address is and what its requirement is.

Now before giving answer of first question I would like to give the answer of our second question. Let’s consider an application program that generates data to be sent across an internet, for this software places the data in the packet, which contains the protocol address (IP address) of the destination. Software in each host or router uses the protocol destination address to select the next hop for the packet. Once a next hop has been selected, software transfers the packet across one physical network to the selected host or router. To provide the illusion of a single, large network, software works with the IP addresses when forwarding the packets. Both the next hop and destination addresses are the IP addresses.

Now the main problem arises here, when we want to transmit frames across physical network hardware we need hardware address of the destination because the hardware does not understand the IP addressing. So, when a frame is set across a physical network it must use the hardware’s frame format and all the addresses in the frame must be hardware addresses. Consequently, the protocol address of the next hop must be translated to an equivalent hardware address before a frame can be sent. The process of converting IP address to its equivalent hardware address is known as Address Resolution and a protocol address is said to be resolved to the correct hardware address. Address Resolution is local to network that means one computer can resolve the address of another computer only if both computers attach to the same physical network. A computer never resolves the address of a computer on a remote network.

After this explanation I hope you understand a little bit about the Address Resolution Protocol. In the next post I will tell about the various techniques through which Address Resolution takes place. Hope you like this post.

If you have any doubts in any of the topics of Computer Networks then post your problem in the comment. I will try to sort it out.

Network Troubleshooting

Acquiring Network Address problem

I recently solved "ACQUIRING NETWORK ADDRESS" problem on my friend's laptop and I just wanted to pass thing on.
My friend had this problem on his laptop ever since we reinstalled Windows XP. No matter what we tried his laptop just won’t connect to the internet. I have a Belkin N150 wireless router at home; all other laptops would connect but not his. It would get stuck with “ACQUIRING NETWORK ADDRESS”. I referred online help but its all about updating the drivers and other troubleshooting which I have all done.

Like most of us, I did initial troubleshooting on the IP settings, router configurations etc. Also tried updating the device drivers – the Ethernet driver and 802.11g Wireless LAN driver but nothing seem to resolve the problem. After the problem didn’t resolve for a long time, I felt kind of embarrassed as his expectation of me resolving the issue was high being an IT guy LOL :)
But finally I solved the problem, and here’s how I resolved it:-
To solve similar issues, start with the basic troubleshooting as mentioned above like checking IP settings, router configurations etc.

1. Assume you tried the basic troubleshooting
2. Check these setting in Services.msc
1. Start > run > services.msc
2. Make sure these services are started and set to automatic
1. WIRELESS ZERO CONFIGURATION (start | keep on ‘automatic’ )
2. DHCP CLIENT (start | keep on ‘automatic’ )
3. DNS CLIENT (start | keep on ‘automatic’ )

I am not sure if these services are activated by default, but I found they were not in my case. So you can start these services if they are not started.

And the issue was resolved. And we are able to connect to the internet both wired and wireless.

All the services mentioned above viz. wireless zero configuration, dhcp client and dns client can be enabled and set to automatic, as shown in the image below.

 

Hotspot in WiFi Network

A hotspot is any location where Wi-Fi network access (usually Internet access) is made publicly available. You can often find hotspots in airports, hotels, coffee shops, and other places where business people tend to congregate. Hotspots are considered a valuable productivity tool for business travelers and other frequent users of network services.Technically speaking, hotspots consist of one or several wireless access points installed inside buildngs and/or adjoining outdoor areas. These APs are typically networked to printers and/or a shared high-speed Internet connection. Some hotspots require special application software be installed on the Wi-Fi client, primarily for billing and security purposes, but others require no configuration other than knowledge of the network name (SSID).

Understanding Proxy Server

Proxy Server:A proxy server is a kind of buffer between your computer and the Internet resources you are accessing. The data you request come to the proxy first, and only then it transmits the data to you.Proxy servers accumulate and save files that are most often requested by thousands of Internet users in a special database, called “cache”. Therefore, proxy servers are able to increase the speed of your connection to the Internet. The cache of a proxy server may already contain information you need by the time of your request, making it possible for the proxy to deliver it immediately.Security and privacy. Anonymous proxy servers that hide your IP address thereby saving you from vulnerabilities concerned with it. Sometimes you may encounter problems while accessing to web server when server administrator restricted access from your IP or even from wide IP range (for example restricting access from certain countries or geographical regions). So you try to access those pages using an anonymous proxy server.

Public Proxy Server:It is a proxy server which is free and open for everybody on the Internet. Unfortunately most of them are not anonymous.Free service trying to provide list of public HTTP proxy servers. Usually provide small list of proxies with low percent of functioning servers due to hosting restrictions on CPU time (they simply can't allow themselves to check many proxies every second especially in parallel).

What is DHCP Server ?

DHCP is the only responsible to assign IP address to any device.Dynamic Host Configuration Protocol (DHCP) is a network protocol that enables a server to automatically assign an IP address to an individual computer's TCP/IP stack software. DHCP assigns a number dynamically from a defined range of numbers configured for a given network.Today you found almost all wireless access points, many wired Ethernet routers, and computers running Internet Connection Sharing have built-in DHCP servers.Due to this reason DHCP servers are mainly preffered for the small networks in comparison to large networks.DHCP assigns a TCP/IP address when a system is started. Typically, it works like this:
1. A user turns on a computer with a DHCP client.

2. The client computer sends a broadcast request (called a DISCOVER or DHCPDISCOVER), looking for a DHCP server to answer.

3. The router directs the DISCOVER packet to the correct DHCP server.

4. The server receives the DISCOVER packet. Based on availability and usage policies set on the server, the server determines an appropriate address (if any) to give to the client. The server then temporarily reserves that address for the client and sends back to the client an OFFER (or DHCPOFFER) packet, with that address information. The server also configures the client's DNS servers, WINS servers, NTP servers, and sometimes other services as well.

5. The client sends a REQUEST (or DHCPREQUEST) packet, letting the server know that it intends to use the address.

6. The server sends an ACK (or DHCPACK) packet, confirming that the client has a been given a lease on the address for a server-specified period of time.

When we assign IP address statically to any computer then there is always a probability that two computers are configured with the same IP address. This creates a conflict that results in loss of service. Using DHCP to dynamically assign IP addresses minimizes these conflicts

How to install phpmyadmin and apache on centos

1.Installing Mysql:yum install mysql mysql-server
chkconfig --levels 235 mysqld on
/etc/init.d/mysqld start
 mysqladmin -u root password servertest //this is the root and its password that you required when first time login in phpmyadmin here "root" is user and "servertest" is password

2.Installing Apache2:yum install httpd
chkconfig --levels 235 httpd on
/etc/init.d/httpd start

3.Installing PHP5:yum install php
/etc/init.d/httpd restart

4.Getting MysQl support in PHP5:
yum search php
yum install php php-mysql php-common php-gd php-mbstring php-mcrypt php-devel php-xml php-xmlrpc
/etc/init.d/httpd restart

5.Installing phpMyAdmin:
cd /var/www/html
wget http://sourceforge.net/projects/phpmyadmin/files/phpMyAdmin/2.11.11.1/phpMyAdmin-2.11.11.1-english.tar.gz
tar xvfz phpMyAdmin-2.11.11.1-english.tar.gz
mv phpMyAdmin-2.11.11.1-english phpmyadmin
cd phpmyadmin
cp config.sample.inc.php config.inc.php
nano config.inc.php
a file will open just type and replace,cookies,with,http,
service httpd restart

UK Cities to get Wi-Fi Coverage.

The United Kingdom has unveiled plan for a city-wide Wi-Fi access in the following cities: Birmingham, Cambridge, Edingburgh, Leeds, Liverpool, Manchester, Nottingham, Oxford and the London boroughs of Kensington and Chelsea, Camden and Islington. This will give resisdents and visitors of those cities broadband wireless Internet access from laptops, PDAs and mobile phones. The project is being executed by European wireless provider The Cloud. The first phase of the project is expected to be completed by March 2006. The system will be made available to ISPs to offer services.People who want to use the wireless network will pay one of the ISPs for access, and revenues will be split between The Cloud, the local council and the ISPs. With the increasing popularity of Wi-Fi mobile phones, this is a good news for VoIP users and service providers. Also people can now use there favourite voip applications on mobile devices anywhere within those cities. I think the announcement of Skype-Netgear Wi-Fi mobile phone couldnt have come at a better time.

Send and receive SMS with Skype

You can now receive sms on your skype client using “sms to skype” and you can send sms to any GSM phone using “skype to sms”. Sms to skype and skype to sms are services offered by connectotel. Your skype username has to be approved by connectotel to be able to use the service and this normally takes about 24 hours. Check out http://www.connectotel.com/ for information about how to setup your skype and GSM mobile phone for these services.

Virtual Phone Lines and DID (Direct Inward Dialing)

For those interested in virtual phone lines that they can integrate with their sip or iax clients as a call-in number, such can be obtained from www.virtualphoneline.com. They have phone numbers for so many countries around the word and they are actually acting as the retail arm of didx.net which is whole sale only DID (Direct Inward Dialing) solution. This is particularly useful because most of the popular voip applications that we use have call-in numbers for some few countries only. Want to know more about DID ? Check out this article at http://www.voip-info.org/wiki-DID

Global Crossing Now Avaya SIP-Compliant

Global Crossing announced that its enterprise Voice over internet Protocol portfolio is fully compliant with Avaya’s Session Initiation Protocol (SIP) telephony products. SIP is an open signaling standard that allows carrier and enterprise voice equipment to interoperate over an IP network via SIP trunks. SIP trunk services are an enterprise networking category that uses new efficiencies in network design and capabilities via SIP-enabled applications. “We’re proud to be the first global service provider to receive SIP interoperability compliance certification from Avaya, “said Anthony Christie, Global Crossing’s chief marketing officer. GlobalCrossing is a member of the Avaya DeveloperConnection Program, which develops, markets and sells third-party products that interoperate with Avaya technology. Eric Rossman, vice president, developer relations and technical alliances, Avaya called the announcement “a big step towards establishing SIP as an open standard for all signaling across both enterprise and service provider networks.” Global Crossing currently runs more than two billion minutes per month of VoIP traffic over its private, global backbone. Avaya’s Converged communications Server 3.0 and its SIP Enablement Services module works with Communication Manager software, the company´s flagship IP telephony software, supported by Avaya media servers, gateways and SIP telephones.

Configuring VoipBuster on X-lite

This post is to give information about how to configure VoipBuster on X-Lite softphone. In X-Lite open ‘menu’ and select ’system settings’ then ‘sip proxy`, from the list of proxies deplayed select the an available proxy. You should then enter the settings below: Enabled YES Display Name (VoipBuster user name) Username (VoipBuster user name) Authorization User (VoipBuster user name) Password (VoipBuster password) Domain/Realm sip1.voipbuster.com SIP Proxy connectionserver.voipbuster.com Out Bound Proxy sip1.voipbuster.com Leave all other settings as default. This configuration is working for me. I am still working on configuring VoipStunt on X-lite as soon as it start working I will post the configuration settings here.

Benefits of Business Ethernet For a Wide Area Network (WAN) Design

The choices today for Wide Area Network (WAN) design are wide and varied. No pun intended. Relying on the same old legacy options is no longer necessary with the maturation of Business Ethernet interconnectivity. Your voice/data transmission deserves better.
Too often businesses looking to upgrade an existing voice/data network infrastructure... or install a new network for whatever reason... tend to gloss over the advantages a Business Ethernet backbone may present. This may be due to a simple lack of understanding, or perhaps a rush to judgment relying on "what you know" for the final decision.
This is unfortunate as Business Ethernet today presents potential benefits over legacy systems such as TDM (e.g. DS3 bandwidth) and SONET (e.g. OC3 circuits) when the right conditions are present. Upon closer examination these improvements are marked and include the most obvious one. That being a significant cost savings in most cases.
Some benefits of Business Ethernet you should be aware of include...
1.) provides unlimited reach over Wide Area networks (WAN).
2.) enhances network performance by providing predictability, service guarantee, and management capabilities that previously were given only in SONET/SDH or ATM networks. This is done by the five carrier-class attributes: standardized services, scalability, reliability, Quality of Service, and Service Management.
3.) there are potential benefits of upgrading to Business Ethernet *if* the sites that can be upgraded are reaching their capacity limits (i.e. average around 70-80% link load for extended periods of time).
4.) typically cost per megabit of a Business Ethernet service is lower than of an equivalent legacy service, which allows getting larger amounts of bandwidth without increasing the overall service cost. By doing so, the congestion levels can be lowered and application performance improved.
In saying this it must be stressed that Business Ethernet is just another data transmission technology (rather than a universal "silver bullet"), and each individual migration case needs careful consideration and cost/benefit analysis.
Approaching this from a non-technical position, when setting out to design a solution you first need to ask what are the types of networks and applications you need to support? For example, are the network topologies linear or ring, and point-point or multipoint? If you are trying to connect pairs of sites with point-point circuits in a single metro, the choice of technology and equipment would be different than if, say you need to interconnect multiple customer sites in a point-to-multipoint or multipoint configuration.
SONET ADMs (ad-drop multiplexer) that support Business Ethernet interfaces could be utilized in the first instance to provide Ethernet Private Lines (EPL). For large complex networks, an MPLS core (Multi-Protocol Label Switching) may be required, although there are Business Ethernet platforms that can provide the necessary interconnectivity at Layer 2. If you are trying to interconnect multiple locations over a SONET ring, RPR (resilient packet ring) solutions are another alternative. Finally, you also need to take into consideration whether you have customer applications that require specific QoS (quality of service), especially if voice and video traffic are to be mixed with data application traffic in any topology other than EPL.
Once you have defined the requirements for Bandwidth, scaling, latency, coverage and inter-connectivity... you can then plan your aggregation and core network. Obviously resiliency, scalability, manageability (network and service) and some aspect of network intelligence play a part in the design.
Now that you have a basic understanding of the possible benefits of Business Ethernet... don't overlook that potential in the final decision on your WAN network design. Although this process may seem to be complicated it really doesn't need to be. Plus, you can always take advantage of the no cost assistance available from Network Solutions to walk you through step by step.

Michael is the owner of FreedomFire Communications....including Network Solutions. Michael also authors Broadband Nation where you're always welcome to drop in and catch up on the latest BroadBand news, tips, insights, and ramblings for the masses. For quality Business Ethernet service, protect yourself and your investment by comparing amongst 30 first and top tier carriers where you have a Low Price Guarantee. For more information about Business Ethernet and finding your best deals and options,

Hosted IP PBX's Enterprise Solution For Samll to Medium Size Businesses

With all of the different flavors of VOIP in the marketplace today, products like Vonage do not bode well for an office with more than a few employees. The other route is purchasing a VOIP enabled key system. Well, I would like to mention a third option that is often overlooked, the Hosted VOIP PBX.

The Hosted IP PBX is a great solution for many mid-sized companies looking for the advantages of an enterprise type of phone system but not wanting to spend the capital to acquire one. Plus you get many more inherent advantages a traditional phone system can not offer you. Let's look into detail what these advantages are in comparison to a traditional key or PBX phone system.

First, let's do a comparison of features between the different solutions. Typically, when buying a traditional system you are limited by the expansion of how many cards and ports the unit can acommodate and when making any changes like moves or adds, you need to pay a technician to come out and service the unit. With a hosted system the technology resides in the phone companies network, so any type of adds, moves or changes can be done easily by you through a web browser and a secure login website, this removes the cost of hiring someone to do this. It also adds tremendous power for redundancy and backup situations. For example, you have an awesome weather event such as a snow storm (which being from Buffalo is my point of reference) and most people can not make into the office, you can get on your broadband connection at home, login and forward all of your calls to any number in the world, like your cell phone or home phone. This way you still will be able to be productive.

Additionally, with a traditional phone system, you have to purchase additional software to get added features. In a hosted environment the upgrades are automatically propagated down to your phone giving you things like unified messaging (getting voicemail files on your computer and using your address book to dial phone numbers), hot desking (being able to go between offices and logging onto any phone and it will not only route all of your calls to you automatically, but will also bring over your speed dials and all of your custom phone settings to that other office phone) and any new enhancements that the software developer creates.

Finally, cost. A traditional system purchase includes phones, separate phone cabling, the box in the phone closet, a voice mail system and any additional cards or software you need to give it the features you want such as auto attendant, IVR functionality, etc. A hosted system only requires data cabling, the phones, a switch and a router. This allows approximately a 40% reduction in upfront expense versus traditional phone systems and at least a 60% reduction against a VoIP system that resides on site.

In summary, a hosted VOIP system is an excellent choice for the mid sized business due to the fact that they can achieve enterprise functionality at a fraction of the cost while also inheriting redundancy not heard of in this market segment. But, you should always consult with a professional to help guide you through advantages and disadvantages of the choices currently out there and find the solution that best suits your businesses current and future needs.

Six Questions to Determine if You're Ready to Analyze 10GbE Traffic

While the cost for 10GbE is coming down and adoption is rapidly rising, there remain challenges in analyzing 10GbE traffic, most notably because the industry has yet to achieve real-time analysis at 10GbE line rates. However, 10GbE analysis is available and does not have to be limiting in terms of results. Below are six questions that will help determine if your organization is fully optimized for analyzing 10GbE traffic.

1. Are you being specific enough?

It's important to know exactly what you want to capture and what information is going to be most beneficial for your analysis. Your requirements will likely vary between each network segment and odds are you are going to have to capture data at several locations. An excellent way to analyze 10GbE traffic, especially when utilization is high, is to use post-capture analysis and only save the data to a disk in real-time. Trying to capture and analyze simultaneously, in real-time, on highly utilized network segments puts much more strain on the system than if you just save data to a disk for post-capture analysis. 

2. Do you REALLY know your network?

Knowing how you expect the network to be performing is all the more critical when trying to analyze highly utilized 10GbE segments. If you're already embroiled in a complex network analysis firefight it's too late to realize that your ability to assess "normal" conditions on the network may be lacking. To get a sense of "normal" conditions before trouble arises, you should perform and archive baseline measurements across specific network traffic like HTTP and key business applications over typical cycles - like an hour, a day, and a week, for the network as a whole. Other metrics to consider include understanding packets size distribution as well as protocol and node usage over time, uncovering cycles in these metrics, which provide a "fingerprint" of your utilization. That way you will always have a clear view of the network for comparison when trouble arises. Only after convincing yourself that the basic data is in place and being collected and analyzed should you embark on detailed analysis and drill-down of packet-level data.

3.  Are you sticking to the essentials?

The temptation is to try to capture and analyze everything, especially when the source of the problem is not immediately known. But quite often certain conditions can be immediately ruled out, and using these clues to limit the collection and analysis to only what is necessary dramatically improves network analysis performance. You always have the option to customize analysis by turning off modules that are not important to the current exercise. Modules such as wireless network performance can be turned off, especially in 10GbE analysis, because odds are they are not relevant to the problem being investigated. The key is to customize your usage and take advantage of it. 

4. Do you know your limits?

Even after analysis has been streamlined to only essential areas of the network, data capture for network analysis on 10GbE networks generates a great deal of data quickly, and managing the data becomes a significant challenge. Regardless of the system used, the data is typically stored for subsequent retrieval and post-capture analysis. The two most common formats are standard packet files and databases. In either case, two metrics to manage closely are file size and frequency of disk writes. Though intuition may lead you to think that the larger the file size the better, this is often not the case as very large files require very large memory footprints to open. If the files are too large they will be unworkable on the computer being used for analysis. Smaller files, however, typically lead to more frequent disk writes, and this can rob the system of precious resources for performing the actual packet capture. Optimum performance is achieved with a balance of these two demands, and this is different depending on the hardware resources available. One rule of thumb to keep in mind is that if files are being created every 30 seconds or less, it's going to increase strain on achieving the maximum packet capture rate significantly. Starting with reasonable sized buffers and files makes all the difference. We recommend that you start with 256MB buffer for packet capture and 128MB for files to be created. After a few captures you'll quickly determine if either of these parameters can be better optimized for your system. Also, try to use the lowest number of simultaneous captures as possible. In several systems, you're allowed to create as many captures as you want, but you need to remember that for each capture you open more memory is reserved for buffering and less is available for data processing. 

5. Are you filtering and slicing?

Filtering is a way of limiting the overall number of packets captured and stored based upon user-specified criteria. Slicing captures and stores all of the packets, but it truncates the packets after a certain length, typically allowing you to store the header information but slice off the payloads. In both cases the same result is achieved, the overall amount of data to store is significantly reduced, freeing up more processing power for capture and analysis and more disk space for storing the data that's truly important to the current analysis task. 

6. Are you being reasonable?

Most network analysis systems allow multiple users to connect to the hardware performing critical network data capture and analysis tasks. Put a limit on users. Nominate an owner for each system that will monitor filters and captures. Make sure it's understood who has the authority to go kill a capture. Too many users with too many options is a recipe for disaster. You can always scale with additional systems if needed.

VoFi Analysis: Get Started with our Guide to VoFi Monitoring, Analysis, and Troubleshooting

Online mobile VoIP (or VoFi) is coming. In-Stat anticipates 171.3 million users by 2013, with annual revenues projected at $10.8 billion ("Mobile VoIP - Transforming the Future of Wireless Voice; In-Stat In-Depth Analysis," Frank Dickson, Sept. 2009). Previously on our blog we've talked about why VoFi and why now, specifically the benefits of VoFi. Now we'll focus on VoFi monitoring, analysis, and troubleshooting.

Before you panic, take a deep breath. Analyzing VoFi traffic is basically the same as analyzing VoIP traffic. Remember though that wireless exacerbates factors such as jitter, latency, and packet loss that affect VoIP. Watch Using VoIP Metrics to Identify Network Problems for the specifics.

Begin at the Beginning: Your End User's Call

When problems arise with VoIP or VoFi applications, you start in the same place. Your first step - before you begin to worry about statistics or packets - is to take the time to listen to representative calls. You want to hear what your end users are experiencing. Your ear will reveal telltale signs of latency, jitter, and packet loss. Be sure your VoIP analysis application supports playback of call audio, specifically the playback of individual RTP streams as well as the playback of the complete call. Without the audio, you can spend hours tracking down problems that aren't due to either the application or the network - for example, clicking due to a damaged handset.

Take Your Network's Pulse

Once you have listened to the call, you'll want to take a look at what's going on in your network.

Figure 1: Overview of Network Health

Immediately you see what you heard - the call quality was poor. The Mean Opinion Score graph gives an average over all calls occurring on your network. In this example there's just one call, so you see the average for the duration of that call.

Dig Deeper

With Expert Events you're able to verify what your ear told you.

Figure 2: Event Summary

With this call, you can see that there are a lot of physical errors: late packet arrival, retries, out of sequence packets, packet loss, excessive jitter, and more. With the cause identified, you can quickly begin to fix the problem. Looking at the call in its entirety, you'll notice the call is closed, it had a successful ending - meaning the call wasn't truncated - what CODEC was used, how long it was, and what the Mean Opinion Score was.

Figure 3: Call Statistics

In this example, the mean opinion score of 2.5 lets you know that the quality of the call was pretty poor. In the media view, you can drill down into each segment leg to determine why the quality was poor.

Figure 4: Call Details - R Factor, Mean Opinion Score, Packet Loss Percentage, One Way Delay, Etc.

Understand the Differences between Wired VoIP and VoFi Calls

The next two figures show both a Wired VoIP call and a VoFi call packet-by-packet. (For an in-depth discussion of these calls, watch Anatomy of a VoFi Call: Packet-by-Packet.) You'll notice that they're pretty similar. The protocols used are different and with VoFi there's the additional step of authentication.

Figure 5: The Anatomy of a Wired VoIP Call

The differences involve: wireless segments instead of wired segments; signal interference; and wireless roaming.

Figure 6: The Anatomy of a Mobile VoIP (VoFi) Call

Learn More

Last week in Toronto, Joe Habib, Director of Global Services, presented "QoS of IP Telephony: Slaying the Three-Headed Beast of Jitter, Latency, and Packet Loss" at IT360. His presentation (PDF) is now available online. If you're interested in ensuring QoS for your current (or future) VoFi deployment, you should definitely check it out.

In the presentation, you will learn:

• What six factors contribute to poor voice quality
•  How to establish metrics for evaluating VoIP call quality
• How to balance high-speed, bursty data requirements with requirements of high quality voice calls
• How to capture data for VoFi Analysis and use VoIP metrics to identify developing problems
• How to analyze a VoFi call packet-by-packet and verify voice quality with call playback

Wireless Roaming and its Effect on Quality

Roaming occurs when a handset moves out of the range of one access point into the range of another. It gives users the mobility to move around within a local coverage area and still be connected to the network. However, roaming is one of the primary reasons why users experience problems on wireless networks. Excessive roaming times lead to poor quality for voice and video over wireless and can lead to dropped calls or data connections.

Roaming usually involves a channel change, but that depends on the type of technology deployed. If it's a multi-channel architecture, which is most likely the case, a channel change is required. When roaming occurs, the client needs to be re-authenticated and re-associated with the new access point, which takes longer than 150 milliseconds in most instances, especially when advanced features like WPA2 and WMM are in use. Most organization's wireless networks are outfitted with multiple access points (APs) and users can experience poor signal strength and performance despite proper coverage in the area if the client is connected to the "wrong" AP. Even in the most modern, centrally managed systems, the wireless client is the one who decides when to switch from one AP to another. This decision is typically determined based on the current signal strength and is executed by the underlying software controlling the wireless client radio (the "supplicant"). This software is different from manufacturer to manufacturer and from device to device, so the way the decision to roam is made varies widely. In most cases, the wireless client will wait too long and as a result the available signal strength lowers, before the client switches to an AP with greater signal strength.

New and improved standards are available that specify the conditions for "fast roaming," enabling transitions that take as little as 5 - 10 milliseconds. These specifications include:

• 802.11i - with opportunistic key caching so there is no re-authentication step
• 802.11r - fast BSS transition, which optimizes the hand-off as clients move from one access point to another
• 802.11k - radio resource management of WLANs allows re- authentication to be maintained between multiple APs and has predictive capabilities

These new standards (802.11i isn't new, but it's still part of an improving situation for roaming) allow APs greater control in determining when roaming should occur and the APs are more in tune with the current performance of, and demands on, the wireless network. However, this situation is even better when the overall wireless network is under the control of a centralized manager. The issue is that adoption of 11k and 11r has been very slow, especially in wireless clients, and until adoption increases significantly users will continue to suffer slow AP transitions when roaming, leading to poor voice and video over IP performance.

In the meantime, the best approach is to carefully monitor and analyze the roaming activity on your network. Obtaining a complete and accurate view requires real-time aggregation of data from multiple channels and APs, with integrated analysis that leads to detailed reporting - who is roaming, how long each event is taking and what does the average look like for each AP. The end result is simple, yet the process is complex, demonstrating why proper network analysis tools are key to staying productive.

Has World Cup Fever Spread to the Network?

It's called World Cup fever for a reason. With millions of people watching and reading related news online, it undoubtedly increased Internet traffic. In fact, people apparently care more about soccer than they do the presidential election. The very first day of the tournament, traffic exceeded the previous record of 8.5 million views per minute (vpm), which occurred when Barack Obama was elected. According to measurements by Akamai, traffic for news sites on June 11 started to climb steadily at 6 am ET and peaked six hours later, reaching nearly 12.1 vpm.  And the fact that June 11 was a workday didn't stop people from watching. People turned to their office computers to follow the action. Being able to identify high talkers and effectively manage traffic is a must for organizations that want to stay productive and successful.

Below are some considerations for enterprises in regards to their networks during times of high traffic: 

Understand how your network performs normally

The only way a company can improve network performance is to know where they stand in terms of network demands. Then they can measure success against those baselines. By looking at Internet connections, WAN links, WLAN environments and the data center, enterprises can get a sense of how their network normally acts. A network analyzer can also help organize this information into a report that can be used to not only solve issues that currently exist, but also to allow organizations to go back in time to validate performance and bandwidth utilization as necessary.

Prune and clean WLAN traffic

Remove unnecessary traffic. Devices like printers, support stacks and protocols that aren't in use in the environment can be eliminated. Sometimes, protocols that help manage the network, like routing protocols and SNMP can be found, hogging valuable bandwidth without any purpose.

Know your options

Consider a Web surfing policy. The 2010 FIFA World Cup lasts from June 11 through July 11, 2010 and will likely suck up a lot of bandwidth. Having a set policy in place will help keep traffic down and is an option to be explored. However, getting employees to abide by regulations it's often more of challenge than it's worth.

The fact is, it is important to see new trends approaching and make changes to the network to account for an enterprise's behavior. Popular events can erode profitability and corporate security, as employees not only watch but also participate in social media discussions and gamble online. Review network analysis measures and policies now, so when 2014 rolls around, networks stay healthy and humming.

Why Deep Packet Inspection Isn't Just for Network Engineers

Network troubleshooting using deep packet inspection is a tried and true approach for network engineers - no one would ever doubt this approach when a difficult problem is plaguing the network. But suggest the use of deep packet inspection for troubleshooting slow applications and you'll likely get some blank stares. Deep packet inspection is the domain of network engineers, not application engineers, right?

Not necessarily. Analyzing decoded packet headers is definitely more suited to a network engineer, but what about the payload data from all the packets? Most network engineers find little value in the payloads, often times they filter them out to conserve analysis resources. But payloads can be of high interest to application engineers investigating application problems, including slow response time.

Consider the example of a help desk application used by a large online retailer. Support professionals, who access the help desk application for each customer call they receive, begin to experience slow response times from the application and of course the initial report is that the network is the problem. A network engineer begins his investigation and after a short time, calls in the application designer stating the problem is the application, not the network. "How do you know that," asks the application engineer? "Simple", says the network engineer. "Your application is generating the following messages. Your server command was deadlocked with another process and has been chosen as a deadlock victim. Re-run your command. And The rollback transaction request has no corresponding BEGIN TRANSACTION". Flabbergasted, the application engineer exclaims, "Where did you get that information?" "From the packet payloads involved in the slow response time transactions on the network, using deep packet inspection network analysis troubleshooting. You should try it sometime."

Deep packet inspection can provide greater value than simple network troubleshooting. Application engineers can certainly benefit, both in troubleshooting application problems and analyzing the overall behavior of an application before trouble is reported. The following four steps should be done to quickly isolate and analyze specific application data:

1.  Capture data at the appropriate location
For application analysis and tuning, it's best to locate a distributed network analysis software probe or appliance in the data center in line with the application and database servers. This will capture the data for all application users, whether local or remote

.

2. Save packet data to disk
By saving packets to disk and employing post-capture analysis, you can take your time in doing your analysis, without worrying about missing key data.

3. Filter stored packet data for the application of interest
Some solutions make this easier than others, but this step is crucial in creating a data set that is manageable and applicable to the application you wish to analyze. This can often be done by filtering out all traffic except traffic that has the source or destination IP of your application server or servers. If it's a troubleshooting exercise and the problem is isolated to a particular client, you can even further refine the filter to just the IP to IP conversation between the client and the server. 

4. Use built-in analysis features to look for common faults

Before diving in and looking for complex, one-off faults, use the built-in fault detection and analysis capabilities of your analysis software (again, these features can vary wildly between competing solutions) to look for common issues, like one-way traffic, database client errors, slow server response time, failed login, resource errors, etc.

Overall, even though you may get some awkward stares for suggesting deep packet inspection  to troubleshoot slow applications, in the end it's worth it because, you'll not only keep the network healthy but employees happy and productive.