Linux System Administrator Resources

2011-12-25T08:19:00.000-08:00

"Automation is not luxury, it is required."

PERL SOAP Programming Tutorial

2009-10-07T13:14:00.000-07:00

http://www.webmonkey.com/tutorial/Get_Your_Feet_Wet_With_SOAP

http://www.perl.com/pub/a/2001/01/soap.html

What Is SOAP?

SOAP, or the Simple Object Access Protocol, is a protocol designed to help web applications send messages to each other. It's got a very simple, portable structure, based on XML, and it can travel via HTTP, so it's lightweight and easy to implement, plus it's independent of language and platform. And thus the "Simple" part of the acronym, without which we'd now be learning about "OAP," which isn't nearly as puntastic.

Say this application you're writing needs to convert any European Economic Community currency to euros, and vice versa, at the current market rate. Your application can send a brief SOAP request to a server that does the calculation and returns a response, also in SOAP.

Why is this neat? Well, maybe your application is written in Java, and the server's doing its calculation in Perl. As long as they both use SOAP, the transaction is perfectly clean and simple. Also, if your application is running on a computer with web access, the SOAP messages can be sent via HTTP, through port 80. Using port 80 is nice because it doesn't require any extra setup, and any firewall sitting in the way assumes it's just more web traffic, and lets it through, without the long lines and cavity searches that often crop up if you set aside a dedicated port. Three, SOAP is an open protocol (consult the W3C's spec for SOAP 1.2 for more). There are a number of freely downloadable SOAP client and server tools and libraries that can be bent to your needs.

SOAPing Up

A SOAP message is no more and no less than an XML document, sent via some sort of transport protocol. HTTP is the most common way of sending SOAP messages, although SOAP is flexible enough to work with pretty much any transmission protocol you like.

In this tutorial, we're going to use SOAP::Lite, a set of Perl modules that makes dealing with SOAP a breeze. If you happen to dislike Perl, there are plenty of other implementations:Axis, which runs on Apache, Microsoft .NET SOAP, if you like Visual Basic or C#, or any of a hudred more. Or write your own. But here, today, we are using Perl.

So download and install SOAP::Lite. You can get SOAP::Lite from the developer's site, soaplite.com, or use CPAN to grab it automatically and take care of any dependency issues. You'll want to put it on your Web server as well as on the machine you're going to write a client application on. To install it from a command line, you can type ...

 perl -MCPAN -e

... which will give you a CPAN shell, then ...

 install SOAP::Lite

Follow the prompts, and soon enough you're all lathered up and ready to go.

SOAP::Lite requires MD5, XML::Parser, MIME::Lite, and MIME::Parser, which you probably have already if you have a relatively modern working Perl install. If not, CPAN's got 'em.

I'll wait here, blowing bubbles, until you've done that.

Carving A Quick SOAP Server

All set? Now we're going to put together a real quick SOAP server that will generate a (pseudo)random number between 1 and 10. All together now, in Perl:

  #!/usr/bin/perl -w
use SOAP::Transport::HTTP;
SOAP::Transport::HTTP::CGI
   ->dispatch_to('Random')
   ->handle;
package Random;
   sub choose {
         $random = int(rand(9))+1;
   return $random;
   }

The second half of that script generates and returns a random number - the first half, with dispatch_to and handle, wraps the procedure in a SOAP bubble. In essence, it's telling the HTTP server that any calls that come in for Random should be sent to SOAP::Lite, via this script.

Save this script in your web server's cgi-bin directory, set its permissions so it's executable, and it's ready to go. Now let's write a corresponding client script to use it.

#!/usr/bin/perl -w
use SOAP::Lite;
print SOAP::Lite
-> uri('http://myserver.com/Random')
-> proxy('http://myserver.com/cgi-bin/random.cgi')
-> Random()
-> result;

Quick, update your resume. You've built a complete web service using SOAP. Run that script, and voila! A random number, requested and delivered via SOAP, just for you. Let's take a quick look at how it does what it does.

What's Happening?

When the client is run, it contacts the server via SOAP, gets a random number freshly generated for it, and outputs that number. The Perl modules are handling all the nasty behind-the-scenes work of creating HTTP headers and encoding XML schemas.

The proxy() method points to the URL of the actual procedure you want to run on the server -- in this case, the script we just wrote.

It's not to be confused with uri(), which is where the namespace of the server-side SOAP code is defined. The argument to the uri() method looks like a URL, but it's not. The "http://" part of uri()'s argument specifies the transport protocol; the server name is the server name, right; and then the class to be invoked is last. There isn't a directory called Random on the server.

What's happening behind the scenes is this:The client script sends a SOAP payload to the server via HTTP. This message consists of an HTTP header followed by a SOAP envelope generated by the Perl module.

What the client sends to the server actually looks something like this:

  POST /random.cgi HTTP/1.1
Content-Type:text/xml; charset="utf-8"
Content-Length:124

The "xmlns" lines declare default namespaces, whose purpose is to ensure that there's no conflict between the envelope we're creating and another one somewhere that might use the same name. We're referring to predefined namespaces for our schema and envelope, ones that are just sitting there on the W3C's machines waiting to be used. But this is the aspect that SOAP::Lite takes care of for you, so understanding it is secondary for the time being. Again, the W3C specification explains it all in great detail.

Seeing the SOAP Light

SOAP::Lite has a lot of tricks up its sleeve. For example, if you're going to be making a whole bunch of remote function calls, there's an easier way than sending each one on its way with

dispatch_to()

. If you initialize the module in your script with ...

  use SOAP::Lite +autodispatch =>
    uri =>  'http://myserver.com/Random'
    proxy => 'http://myserver.com/cgi-bin/random.cgi'

... then any time your script calls an undefined method, the call will be autodispatched via SOAP to the proxy you specify.

There is a lot more to SOAP, and SOAP::Lite, but you're on your way, so I won't slow you down. For information about error handling techniques, passing complex information and objects back and forth, and suchlike, there is a bunch of useful documentation to be found at cookbook.soaplite.com.

If you need ideas or inspiration, XMethods.com has a useful and entertaining collection of web services you can check out and use.

Network Security Scan

2009-10-07T09:03:00.001-07:00

http://www.openvas.org/index.html

Configure DHCP with LDAP

2009-09-22T10:44:00.000-07:00

http://wiki.github.com/dcantrell/ldap-for-dhcp

http://www.grotan.com/ldap/dhcp-ldap-readme

Look at Black listed IPs

2009-09-16T08:59:00.000-07:00

http://www.backscatterer.org/

How to unregister/register System from RedHat Satellite Server

2009-09-04T08:17:00.000-07:00

http://kbase.redhat.com/faq/docs/DOC-8037

How to sign your custom RPM package with GPG Key

2009-08-03T08:03:00.000-07:00

http://fedoranews.org/tchung/gpg/

Problems && Solutions

2009-07-16T07:35:00.000-07:00

Problem: ssh login to one of the server was taking a long time (almost minutes).

Solution: The problem was solved by adding following lines at /etc/ssh/sshd_config:

UseDNS no

What is running on port?

2009-06-12T09:13:00.001-07:00

lsof -ni udp:161

View actual physical memory usage on Linux

2009-06-08T11:23:00.000-07:00

free

free command displays amount of total, free and used physical memory (RAM) in the system, as well as shoing information on shared memory, buffers, cached memory and swap space used by the Linux kernel.

Syntax of free

free -[options]

Example usage of free

free -m

The command will display information about physical memory in MB.

free -m -s 5

The command will activate continuous polling delay at 5 seconds apart, and then display memory status in megabytes on terminal. Any floating point number for delay can be specified.

free -t -m

Same with “free -m”, but -t switch will display a line containing the totals of physical memory and swap space.

Passwordless ssh login

2009-06-05T10:42:00.000-07:00

1 Generate keys

Type:

   ssh-keygen -t rsa

And do not enter a passphrase unless you wanted to be prompted for one during file copying.

Here is what you will see:

   $ ssh-keygen -t rsa
  Generating public/private rsa key pair.
  Enter file in which to save the key (/home/User/.ssh/id_rsa):
  Enter passphrase (empty for no passphrase):

  Enter same passphrase again:

  Your identification has been saved in /home/User/.ssh/id_rsa.
  Your public key has been saved in /home/User/.ssh/id_rsa.pub.
  The key fingerprint is:
  5a:cd:2b:0a:cd:d9:15:85:26:79:40:0c:55:2a:f4:23 User@JEFF-CPU

2 Copy public to machines you want to upload to

id_rsa.pub is your public key. Copy it to ~/.ssh on target machine.

Put a copy of the public key file on each machine you want to log into. Name the copy authorized_keys (some implementations name this file authorized_keys2)

Then type:

     chmod 600 authorized_keys

Then make sure your home dir on the remote machine is not group or world writeable.

Keeping a Log Of Daily Network Traffic for ADSL or Dedicated Remote Linux Server

2009-06-03T13:10:00.000-07:00

Almost a year ago, I wrote about Linux MRTG configuration how-to. However, some user seems to confused with MRTG, most users would like to know - how much traffic actually generated by ADSL/Cable service provider on daily and monthly basis.

MRTG is for network monitoring and it can be use to see how much traffic your server or ADSL router actually generated, however it will not tell you how much megabytes or gigabytes the daily traffic was. For all such home user and people having dedicated single Linux box hosted somewhere remote at IDC/ISP there is a tool called vnStat:

It is a console-base network traffic monitor for Linux (perfect tool for remote Linux box hosted at ISP)
It keeps a log of daily and monthly network traffic for the selected network interface(s).
It collects all data from /proc file system it means normal user can monitor traffic (no need to run vnstat as a root user)
Easy to setup & configure
Ease of use

Step # 1: Install vnstat

Debian / Ubuntu Linux user can install vnstat using apt-get command, enter:

# apt-get install vnstat

Step # 2: Enable vnstat

Once installed, you need to create a database with the following command:

# vnstat -u -i eth0

Where,

-u :forces a database update for interface or creates the database if it doesn’t exist
-i eth0 : use to specify interface

Please note that it will start to collect data via cronjob:

0-55/5 * * * *   root    /usr/bin/vnstat -u

You do not have to install cronjob yourself; it should be automatically configure by apt-get.

Step # 3 View statistics

Display default traffic statistics

$ vnstat

Display daily traffic statistics

$ vnstat -d

Display monthly traffic statistics:

$ vnstat -m

Display all time top10 traffic days:

$ vnstat -t

Try help option to get all query options:

$ vnstat --help


Source:- http://www.cyberciti.biz/tips/keeping-a-log-of-daily-network-traffic-for-adsl-or-dedicated-remote-linux-box.html

Linux display bandwidth usage on network interface by host

2009-06-03T13:05:00.000-07:00

iftop command listens to network traffic on a named network interface, or on the first interface it can find which looks like an external interface if none is specified, and displays a table of current bandwidth usage by pairs of hosts. iftop is a perfect tool for remote Linux server over ssh session.

iftop must be run by the root or the user who has sufficient permissions to monitor all network traffic on the network interface.

Type iftop command at tge shell prompt to display traffic:
# iftop

However, iftop works best when you use filters. For example, if you want to find out how much bandwidth users are wasting or trying to figure out why the network is slow,
# iftop -f icmp
You can display or analyses packet flowing in and out of the 192.168.1.0/24 network:
# iftop -F 192.168.1.0/24
Disable output for DNS traffic by using filter code such as:
# iftop -f 'not port domain'

iftop has many options read man page for further information.

Source: http://www.cyberciti.biz/tips/linux-display-bandwidth-usage-on-network-interface-by-host.html

Restricting Weak SSL Ciphers, F5 BigIP

2009-06-03T11:02:00.000-07:00

v9.x Software

SSL functions are performed and configured using SSL client and server profiles. Replace the clientssl parameter to serverssl to configure server SSL profiles.

Using the GUI

Assuming you use it as the parent profile, modify the built in clientssl profile cipher list as follows;

Browse to Local TrafficProfilesSSLClient
Select the clientssl profile
Select ConfigurationAdvanced
Enter the following in the Ciphers text box: -ALL:!ADH:!LOW:!EXP:!SSLv2:!NULL:RC4:RSA:HIGH:MEDIUM
Click Update

All profiles using the clientssl parent profile are automatically updated.

Profiles not using this parent profile will have to be manually updated, selecting the relevant profile at step 2.

Using the CLI

bigpipe profile clientssl clientssl \{ ciphers \-ALL:\!ADH:\!LOW:\!EXP:\!SSLv2:RC4:RSA:HIGH:MEDIUM\ \}

Source:- http://www.routerzone.eu/wiki/index.php/Restricting_Weak_SSL_Ciphers,_F5_BigIP

nmap : scan a subnet for active IPs

2009-05-12T12:33:00.001-07:00

# nmap -sP 192.168.0.0/24

To test packet lost

2009-05-04T08:38:00.000-07:00

#mtr -r -c 10 myhost.mydomain.com
HOST: xxxxx.xxx.xxx Loss% Snt Last Avg Best Wrst StDev
1. xxxxxxxx 0.0% 10 0.2 0.2 0.2 0.3 0.0
2. xxxxxxxx 0.0% 10 0.6 1.4 0.5 9.2 2.8
3. xxxxxxxx 0.0% 10 2.6 1.2 0.6 3.1 1.0

Generating a syslog message

2009-04-05T10:11:00.000-07:00

#logger -i -t yourname "This is a test"

=> Message should appear at /var/log/messages.

MySQL: show disk space occupied by database

2009-04-02T11:50:00.000-07:00

#mysql -uroot -p -D -e "show table status\G"| egrep "(Index|Data)_length" | awk 'BEGIN { rsum = 0 } { rsum += $2 } END { print rsum/1024/1024 "M"}'

rpmdb: Lock table is out of available locker entries

2009-02-03T09:01:00.000-08:00

rpmdb: Lock table is out of available locker entries

05.27.2007 | Author: major | Posted in Uncategorized

If up2date throws some horrible Python errors and rpm says “rpmdb: Lock table is out of available locker entries”, you can restore your system to normality with the following:

The errors:
rpmdb: Lock table is out of available locker entries error: db4 error(22) from db->close: Invalid argument error: cannot open Packages index using db3 - Cannot allocate memory (12) error: cannot open Packages database in /var/lib/rpm

Make a backup of /var/lib/rpm in case you break something:
tar cvzf rpmdb-backup.tar.gz /var/lib/rpm

Remove the Berkeley databases that rpm uses:
rm /var/lib/rpm/__db.00*

Make rpm rebuild the databases from scratch (may take a short while):
rpm --rebuilddb

Now, check rpm to make sure everything is okay:
rpm -qa | sort

Why does this happen?
When rpm accesses the Berkeley database files, it makes temporary locker entries within the tables while it searches for data. If you control-c your rpm processes often, this issue will occur much sooner because the locks are never cleared.

Find out who are recently logged on to your linux system

2009-01-24T12:02:00.000-08:00

utmpdump /var/log/wtmp | less

PHP + LDAP Tutorial

2009-01-22T12:12:00.000-08:00

http://us.php.net/manual/en/ldap.examples-basic.php

Installing kernel-debuginfo on RHEL 5.2

2009-01-12T11:37:00.000-08:00

#yum --enablerepo=rhel-debuginfo install kernel-debuginfo

Finding Version of linux installed

2009-01-08T13:53:00.000-08:00

#cat /etc/*release

Starting virtual server in a single user mode

2009-01-08T12:29:00.000-08:00

From root domain:
#xm create {domain-name} -c
Example:- xm create rhel5b2-pv2 -c

-> follow the same steps to boot in single user mode as usual.

Displaying Total hard disk size (in Linux)

2008-12-16T07:22:00.000-08:00

[root@test4 ~]# fdisk -l | grep Disk
Disk /dev/hda: 60.0 GB, 60022480896 bytes
Disk /dev/hdb: 200.0 GB, 200049647616 bytes

XEN Virtualization Tutorial

2008-11-21T07:45:00.000-08:00

http://www.linuxtopia.org/online_books/rhel5/rhel5_xen_virtualization/rhel5_ch-virt-system-architect.html

RFC Search URL

2008-10-23T11:35:00.001-07:00

http://www.rfc-editor.org/

System Configuration

2008-10-22T11:46:00.000-07:00

Sharing Mouse and Keyboard between two systems
URL: http://synergy2.sourceforge.net

Network Related Tools

2008-10-22T08:32:00.000-07:00

Nessus -> Security Scanner

URL: www.nessus.org

Advanced IP Scanner
URL: http://www.radmin.com/products/utilities/ipscanner.php

MIB for Dell Server

2008-10-14T13:07:00.001-07:00

http://support.dell.com/support/edocs/software/svradmin/5.4/en/snmp/html/index.htm

http://support.dell.com/support/edocs/software/svradmin/5.4/en/snmp/html/snmpc23.htm#wp1127929

Network speed test applications references

2008-10-10T11:43:00.001-07:00

http://dast.nlanr.net/Projects/Iperf/iperfdocs_1.7.0.php
http://www.ixiacom.com/support/endpoint_library/

iperf (Easy Tutorial):
http://openmaniak.com/iperf.php

Networking Iperf
Last update: 28-Mar-2008

Iperf is a tool to measure the bandwidth and the quality of a network link. Jperf can be associated with Iperf to provide a graphical frontend written in Java.

The network link is delimited by two hosts running Iperf.

The quality of a link can be tested as follows:
- Latency (response time or RTT): can be measured with the ping command.
- Jitter (latency variation): can be measured with an Iperf UDP test.
- Datagram loss: can be measured with an Iperf UDP test.

The bandwidth is measured through TCP tests.

To be clear, the difference between TCP (Transmission Control Protocol) and UDP (User Datagram Protocol) is that TCP use processes to check that the packets are correctly sent to the receiver whereas with UDP the packets are sent without any checks but with the advantage of being quicker than TCP.
Iperf uses the different capacities of TCP and UDP to provide statistics about network links.

Finally, Iperf can be installed very easily on any UNIX/Linux or Microsoft Windows system. One host must be set as client, the other one as server.

Here is a diagram where Iperf is installed on a Linux and Microsoft Windows machine.
Linux is used as the Iperf client and Windows as the Iperf server. Of course, it is also possible to use two Linux boxes.

Iperf tests:

no arg.
-b
-r
-d
-w

Default settings
Data format
Bi-directional bandwidth
Simultaneous bi-directional bandwidth
TCP Window size

-p, -t, -i
-u, -b
-m
-M
-P
-h

Port, timing and interval
UDP tests, bandwidth settings
Maximum Segment Size display
Maximum Segment Size settings
Parallel tests
help

Jperf:

no arg.
-d
-u, -b

Default settings
Simultaneous bi-directional bandwidth
UDP tests, bandwidth settings

Default Iperf settings:
Also check "Jperf section.

By default, the Iperf client connects to the Iperf server on the TCP port 5001 and the bandwidth displayed by Iperf is the bandwidth from the client to the server.
If you want to use UDP tests, use the -u argument.
The -d and -r Iperf client arguments measure the bi-directional bandwidths. (See further on this tutorial)

Client side:

#iperf -c 10.1.1.1

------------------------------------------------------------
Client connecting to 10.1.1.1, TCP port 5001
TCP window size: 16384 Byte (default)
------------------------------------------------------------
[ 3] local 10.6.2.5 port 33453 connected with 10.1.1.1 port 5001
[ 3] 0.0-10.2 sec 1.26 MBytes 1.05 Mbits/sec

Server side:

#iperf -s

Data formatting: (-f argument)

The -f argument can display the results in the desired format: bits(b), bytes(B), kilobits(k), kilobytes(K), megabits(m), megabytes(M), gigabits(g) or gigabytes(G).
Generally the bandwidth measures are displayed in bits (or Kilobits, etc ...) and an amount of data is displayed in bytes (or Kilobytes, etc ...).
As a reminder, 1 byte is equal to 8 bits and, in the computer science world, 1 kilo is equal to 1024 (2^10).
For example: 100'000'000 bytes is not equal to 100 Mbytes but to 100'000'000/1024/1024 = 95.37 Mbytes.

Client side:

#iperf -c 10.1.1.1 -f b

------------------------------------------------------------
Client connecting to 10.1.1.1, TCP port 5001
TCP window size: 16384 Byte (default)
------------------------------------------------------------
[ 3] local 10.6.2.5 port 54953 connected with 10.1.1.1 port 5001
[ 3] 0.0-10.2 sec 1359872 Bytes 1064272 bits/sec

Server side:

#iperf -s

Bi-directional bandwidth measurement: (-r argument)

The Iperf server connects back to the client allowing the bi-directional bandwidth measurement. By default, only the bandwidth from the client to the server is measured.
If you want to measure the bi-directional bandwidth simultaneously, use the -d keyword. (See next test.)

Client side:

#iperf -c 10.1.1.1 -r

------------------------------------------------------------
Server listening on TCP port 5001
TCP window size: 85.3 KByte (default)
------------------------------------------------------------
------------------------------------------------------------
Client connecting to 10.1.1.1, TCP port 5001
TCP window size: 16.0 KByte (default)
------------------------------------------------------------
[ 5] local 10.6.2.5 port 35726 connected with 10.1.1.1 port 5001
[ 5] 0.0-10.0 sec 1.12 MBytes 936 Kbits/sec
[ 4] local 10.6.2.5 port 5001 connected with 10.1.1.1 port 1640
[ 4] 0.0-10.1 sec 74.2 MBytes 61.7 Mbits/sec

Server side:

#iperf -s

------------------------------------------------------------
Server listening on TCP port 5001
TCP window size: 8.00 KByte (default)
------------------------------------------------------------
[852] local 10.1.1.1 port 5001 connected with 10.6.2.5 port 54355
[ ID] Interval Transfer Bandwidth
[852] 0.0-10.1 sec 1.15 MBytes 956 Kbits/sec
------------------------------------------------------------
Client connecting to 10.6.2.5, TCP port 5001
TCP window size: 8.00 KByte (default)
------------------------------------------------------------
[824] local 10.1.1.1 port 1646 connected with 10.6.2.5 port 5001
[ ID] Interval Transfer Bandwidth
[824] 0.0-10.0 sec 73.3 MBytes 61.4 Mbits/sec

Top of the page

Simultaneous bi-directional bandwidth measurement: (-d argument)
Also check the "Jperf" section.

To measure the bi-directional bandwidths simultaneousely, use the -d argument. If you want to test the bandwidths sequentially, use the -r argument (see previous test).
By default (ie: without the -r or -d arguments), only the bandwidth from the client to the server is measured.

Client side:

#iperf -c 10.1.1.1 -d

------------------------------------------------------------
Server listening on TCP port 5001
TCP window size: 85.3 KByte (default)
------------------------------------------------------------
------------------------------------------------------------
Client connecting to 10.1.1.1, TCP port 5001
TCP window size: 16.0 KByte (default)
------------------------------------------------------------
[ 5] local 10.6.2.5 port 60270 connected with 10.1.1.1 port 5001
[ 4] local 10.6.2.5 port 5001 connected with 10.1.1.1 port 2643
[ 4] 0.0-10.0 sec 76.3 MBytes 63.9 Mbits/sec
[ 5] 0.0-10.1 sec 1.55 MBytes 1.29 Mbits/sec

Server side:

#iperf -s

------------------------------------------------------------
Server listening on TCP port 5001
TCP window size: 8.00 KByte (default)
------------------------------------------------------------
[852] local 10.1.1.1 port 5001 connected with 10.6.2.5 port 60270
------------------------------------------------------------
Client connecting to 10.6.2.5, TCP port 5001
TCP window size: 8.00 KByte (default)
------------------------------------------------------------
[800] local 10.1.1.1 port 2643 connected with 10.6.2.5 port 5001
[ ID] Interval Transfer Bandwidth
[800] 0.0-10.0 sec 76.3 MBytes 63.9 Mbits/sec
[852] 0.0-10.1 sec 1.55 MBytes 1.29 Mbits/sec

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TCP Window size: (-w argument)

The TCP window size is the amount of data that can be buffered during a connection without a validation from the receiver.
It can be between 2 and 65,535 bytes.
On Linux systems, when specifying a TCP buffer size with the -w argument, the kernel allocates double as much as indicated.

Client side:

#iperf -c 10.1.1.1 -w 2000

WARNING: TCP window size set to 2000 bytes. A small window size
will give poor performance. See the Iperf documentation.
------------------------------------------------------------
Client connecting to 10.1.1.1, TCP port 5001
TCP window size: 3.91 KByte (WARNING: requested 1.95 KByte)
------------------------------------------------------------
[ 3] local 10.6.2.5 port 51400 connected with 10.1.1.1 port 5001
[ 3] 0.0-10.1 sec 704 KBytes 572 Kbits/sec

Server side:

#iperf -s -w 4000

------------------------------------------------------------
Server listening on TCP port 5001
TCP window size: 3.91 KByte
------------------------------------------------------------
[852] local 10.1.1.1 port 5001 connected with 10.6.2.5 port 51400
[ ID] Interval Transfer Bandwidth
[852] 0.0-10.1 sec 704 KBytes 570 Kbits/sec

Top of the page

Communication port (-p), timing (-t) and interval (-i):

The Iperf server communication port can be changed with the -p argument. It must be configured on the client and the server with the same value, default is TCP port 5001.
The -t argument specifies the test duration time in seconds, default is 10 secs.
The -i argument indicates the interval in seconds between periodic bandwidth reports.

Client side:

#iperf -c 10.1.1.1 -p 12000 -t 20 -i 2

------------------------------------------------------------
Client connecting to 10.1.1.1, TCP port 12000
TCP window size: 16.0 KByte (default)
------------------------------------------------------------
[ 3] local 10.6.2.5 port 58316 connected with 10.1.1.1 port 12000
[ 3] 0.0- 2.0 sec 224 KBytes 918 Kbits/sec
[ 3] 2.0- 4.0 sec 368 KBytes 1.51 Mbits/sec
[ 3] 4.0- 6.0 sec 704 KBytes 2.88 Mbits/sec
[ 3] 6.0- 8.0 sec 280 KBytes 1.15 Mbits/sec
[ 3] 8.0-10.0 sec 208 KBytes 852 Kbits/sec
[ 3] 10.0-12.0 sec 344 KBytes 1.41 Mbits/sec
[ 3] 12.0-14.0 sec 208 KBytes 852 Kbits/sec
[ 3] 14.0-16.0 sec 232 KBytes 950 Kbits/sec
[ 3] 16.0-18.0 sec 232 KBytes 950 Kbits/sec
[ 3] 18.0-20.0 sec 264 KBytes 1.08 Mbits/sec
[ 3] 0.0-20.1 sec 3.00 MBytes 1.25 Mbits/sec

Server side:

#iperf -s -p 12000

------------------------------------------------------------
Server listening on TCP port 12000
TCP window size: 8.00 KByte (default)
------------------------------------------------------------
[852] local 10.1.1.1 port 12000 connected with 10.6.2.5 port 58316
[ ID] Interval Transfer Bandwidth
[852] 0.0-20.1 sec 3.00 MBytes 1.25 Mbits/sec

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UDP tests: (-u), bandwidth settings (-b)
Also check the "Jperf" section.

The UDP tests with the -u argument will give invaluable information about the jitter and the packet loss. If you don't specify the -u argument, Iperf uses TCP.
To keep a good link quality, the packet loss should not go over 1 %. A high packet loss rate will generate a lot of TCP segment retransmissions which will affect the bandwidth.

The jitter is basically the latency variation and does not depend on the latency. You can have high response times and a very low jitter. The jitter value is particularly important on network links supporting voice over IP (VoIP) because a high jitter can break a call.
The -b argument allows the allocation if the desired bandwidth.

Client side:

#iperf -c 10.1.1.1 -u -b 10m

------------------------------------------------------------
Client connecting to 10.1.1.1, UDP port 5001
Sending 1470 byte datagrams
UDP buffer size: 108 KByte (default)
------------------------------------------------------------
[ 3] local 10.6.2.5 port 32781 connected with 10.1.1.1 port 5001
[ 3] 0.0-10.0 sec 11.8 MBytes 9.89 Mbits/sec
[ 3] Sent 8409 datagrams
[ 3] Server Report:
[ 3] 0.0-10.0 sec 11.8 MBytes 9.86 Mbits/sec 2.617 ms 9/ 8409 (0.11%)

Server side:

#iperf -s -u -i 1

------------------------------------------------------------
Server listening on UDP port 5001
Receiving 1470 byte datagrams
UDP buffer size: 8.00 KByte (default)
------------------------------------------------------------
[904] local 10.1.1.1 port 5001 connected with 10.6.2.5 port 32781
[ ID] Interval Transfer Bandwidth Jitter Lost/Total Datagrams
[904] 0.0- 1.0 sec 1.17 MBytes 9.84 Mbits/sec 1.830 ms 0/ 837 (0%)
[904] 1.0- 2.0 sec 1.18 MBytes 9.94 Mbits/sec 1.846 ms 5/ 850 (0.59%)
[904] 2.0- 3.0 sec 1.19 MBytes 9.98 Mbits/sec 1.802 ms 2/ 851 (0.24%)
[904] 3.0- 4.0 sec 1.19 MBytes 10.0 Mbits/sec 1.830 ms 0/ 850 (0%)
[904] 4.0- 5.0 sec 1.19 MBytes 9.98 Mbits/sec 1.846 ms 1/ 850 (0.12%)
[904] 5.0- 6.0 sec 1.19 MBytes 10.0 Mbits/sec 1.806 ms 0/ 851 (0%)
[904] 6.0- 7.0 sec 1.06 MBytes 8.87 Mbits/sec 1.803 ms 1/ 755 (0.13%)
[904] 7.0- 8.0 sec 1.19 MBytes 10.0 Mbits/sec 1.831 ms 0/ 850 (0%)
[904] 8.0- 9.0 sec 1.19 MBytes 10.0 Mbits/sec 1.841 ms 0/ 850 (0%)
[904] 9.0-10.0 sec 1.19 MBytes 10.0 Mbits/sec 1.801 ms 0/ 851 (0%)
[904] 0.0-10.0 sec 11.8 MBytes 9.86 Mbits/sec 2.618 ms 9/ 8409 (0.11%)

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Maximum Segment Size (-m argument) display:

The Maximum Segment Size (MSS) is the largest amount of data, in bytes, that a computer can support in a single, unfragmented TCP segment.
It can be calculated as follows:
MSS = MTU - TCP & IP headers
The TCP & IP headers are equal to 40 bytes.
The MTU or Maximum Transmission Unit is the greatest amount of data that can be transferred in a frame.
Here are some default MTU size for different network topology:
Ethernet - 1500 bytes: used in a LAN.
PPPoE - 1492 bytes: used on ADSL links.
Token Ring (16Mb/sec) - 17914 bytes: old technology developed by IBM.
Dial-up - 576 bytes

Generally, a higher MTU (and MSS) brings higher bandwidth efficiency

Client side:

#iperf -c 10.1.1.1 -m

------------------------------------------------------------
Client connecting to 10.1.1.1, TCP port 5001
TCP window size: 16.0 KByte (default)
------------------------------------------------------------
[ 3] local 10.6.2.5 port 41532 connected with 10.1.1.1 port 5001
[ 3] 0.0-10.2 sec 1.27 MBytes 1.04 Mbits/sec
[ 3] MSS size 1448 bytes (MTU 1500 bytes, ethernet)

Here the MSS is not equal to 1500 - 40 but to 1500 - 40 - 12 (Timestamps option) = 1448

Server side:

#iperf -s

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Maximum Segment Size (-M argument) settings:

Use the -M argument to change the MSS. (See the previous test for more explanations about the MSS)

#iperf -c 10.1.1.1 -M 1300 -m

WARNING: attempt to set TCP maximum segment size to 1300, but got 536
------------------------------------------------------------
Client connecting to 10.1.1.1, TCP port 5001
TCP window size: 16.0 KByte (default)
------------------------------------------------------------
[ 3] local 10.6.2.5 port 41533 connected with 10.1.1.1 port 5001
[ 3] 0.0-10.1 sec 4.29 MBytes 3.58 Mbits/sec
[ 3] MSS size 1288 bytes (MTU 1328 bytes, unknown interface)

Server side:

#iperf -s

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Parallel tests (-P argument):

Use the -P argument to run parallel tests.

Client side:

#iperf -c 10.1.1.1 -P 2

------------------------------------------------------------
Client connecting to 10.1.1.1, TCP port 5001
TCP window size: 16.0 KByte (default)
------------------------------------------------------------
[ 3] local 10.6.2.5 port 41534 connected with 10.1.1.1 port 5001
[ 4] local 10.6.2.5 port 41535 connected with 10.1.1.1 port 5001
[ 4] 0.0-10.1 sec 1.35 MBytes 1.12 Mbits/sec
[ 3] 0.0-10.1 sec 1.35 MBytes 1.12 Mbits/sec
[SUM] 0.0-10.1 sec 2.70 MBytes 2.24 Mbits/sec

Server side:

#iperf -s

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Iperf help:

#iperf -h

Usage: iperf [-s|-c host] [options]
iperf [-h|--help] [-v|--version]

Client/Server:

-f
-i
-l
-m
-p
-u
-w
-B
-C
-M
-N
-V --format
--interval
--len
--print_mss
--port
--udp
--window
--bind
--compatibility
--mss
--nodelay
--IPv6Version [kmKM]
#
#[KM]

#

#[KM]
"host"

#

format to report: Kbits, Mbits, KBytes, MBytes
seconds between periodic bandwidth reports
length of buffer to read or write (default 8 KB)
print TCP maximum segment size (MTU - TCP/IP header)
server port to listen on/connect to
use UDP rather than TCP
TCP window size (socket buffer size)
bind to "host", an interface or multicast address
for use with older versions does not sent extra msgs
set TCP maximum segment size (MTU - 40 bytes)
set TCP no delay, disabling Nagle's Algorithm
Set the domain to IPv6
Server specific:

-s
-U
-D --server
--single_udp
--daemon

run in server mode
run in single threaded UDP mode
run the server as a daemon
Client specific:

-b
-c
-d
-n
-r
-t
-F
-I
-L
-P
-T --bandwidth
--client
--dualtest
--num
--tradeoff
--time
--fileinput
--stdin
--listenport
--parallel
--ttl #[KM]
"host"

#[KM]

#
"name"

#
#
# for UDP, bandwidth to send at in bits/sec (default 1 Mbit/sec, implies -u)
run in client mode, connecting to "host"
Do a bidirectional test simultaneously
number of bytes to transmit (instead of -t)
Do a bidirectional test individually
time in seconds to transmit for (default 10 secs)
input the data to be transmitted from a file
input the data to be transmitted from stdin
port to recieve bidirectional tests back on
number of parallel client threads to run
time-to-live, for multicast (default 1)
Miscellaneous:

-h
-v --help
--version
print this message and quit
print version information and quit
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JPERF

Jperf is a graphical frontend for Iperf written in Java.

1. Installation:

Download Jperf.

Linux

Uncompress the downloaded file:

#tar -xvf jperf2.0.0.zip

Launch Jperf.

#cd jperf2.0.0
#./jperf.sh

If you have the following message, it means that you need to install Iperf with: "apt-get install iperf"

Iperf is probably not in your Path!
Please download it here 'http://dast.nlanr.net/Projects/Iperf/'
and put the executable in your PATH environment variable.

Microsoft Windows

Uncompress the downloaded file with your favorite program.
Access the uncompressed folder called by default "jperf2.0.0" and double-click on "jperf.bat".
Note that the iperf utility is already present in the /bin folder.

2. Examples:

Default settings, bandwidth measurement:
Also check "Iperf" section for more details.

- Linux client:

- Windows server:

Top of the page Jperf

Simultaneous bi-directional bandwidth measurement:
Also check "Iperf" section for more details.

- Linux client:

- Windows server:

Top of the page Jperf

Jitter measurement:
Also check "Iperf" section for more details.

- Linux client:

- Windows server:

I worked on

2008-10-03T12:21:00.000-07:00

-> RADIUS Server installation/configuration.
-> Extreme switch configuration
-> Astaro Firewall installation/configuration
-> Zenoss installation/configuration
-> Network speed testing using different networking tools, i.e. iftop, scp, cadaver etc.
-> 3DNS - Name Server configuration
-> Sawmill upgrade
-> Astaro firewall upgrade
-> Zenoss upgrade
-> perl script to fetch attributes and values from LDAP
-> Research on freeIPA
-> DHCP Server Installation/Configuration
-> Xwiki installation
-> perl script to fetch domain registration information
-> perl script to purge MySQL Database based upon given criteria.
-> vmware installation
-> Fodora DS web interface customization
-> Net-SNMP

Blogging softwares/CMS

2008-10-03T12:19:00.000-07:00

xwiki
Apache Roller
Twiki
joomla
kablink
wordpress

Creating test file

2008-09-03T08:16:00.000-07:00

dd if=/dev/urandom of=/usr/local/src/test123 bs=1024 count=30000

It will create a test file of approximately 31MB.

Webdav Client:

cadaver (Text Based), most of the time comes installed with linux.

eg. cadaver https://webdav.myorg.org/data/share

skunkdav -> JAVA based Application.

iftop

Network speed (upload and download speed) test application.

SNMP Tutorial Links

2008-08-13T06:12:00.000-07:00

http://www.dpstele.com/layers/l2/snmp_tutorials.php

SNMPv3
http://www.netadmintools.com/art485.html

RHEL Administrator Guide References

2008-08-11T11:56:00.000-07:00

https://www.redhat.com/docs/manuals/enterprise/RHEL-3-Manual/pdf/rhel-ig-x8664-multi-en.pdf
https://www.redhat.com/docs/manuals/enterprise/RHEL-4-Manual/pdf/rhel-isa-en.pdf
www.centos.org/docs/4/pdf/rhel-sag-en.pdf
www.centos.org/docs/4/pdf/rhel-sg-en.pdf

Life will be really easy if such .........................

2008-08-08T12:24:00.001-07:00

Personnel

2008-08-08T10:59:00.001-07:00

Tutorial Links

2008-08-01T10:36:00.000-07:00

http://ebook.brawijaya.ac.id/?file=manual

http://ebook.brawijaya.ac.id/index.php3?man=rute/node1.html

http://www.linuxhomenetworking.com

Link to configure tftp server:
http://www.linux-tutorial.info/modules.php?name=Howto&pagename=Clone-HOWTO/setting-up.html

Networking Tutorial
http://www.2000trainers.com/

Applications

2008-08-01T08:01:00.000-07:00

mutt - Non-GUI Mail Clients

tcpdump

head -1 /home/alice/getme

who am i

fuser - display information about the process using the filesystem. It also defines a convenient way to send signals to those processes.

Usage:

fuser -v mount_point
fuser -km mount_point

Saving power consumption

http://lesswatts.org

Environment Variables in Linux

2008-08-01T07:57:00.000-07:00

LANG
LOGNAME

How do you know which startup script is responsible for TCP port 111?

2008-08-01T06:19:00.000-07:00

#lsof -i tcp:111

To verify whether process is running or not

2008-08-01T06:11:00.000-07:00

#pgrep processName

Example:-
[root@st06410722744 ~]# pgrep sendmail
2482
2490

Connecting MySql Remotely

2008-08-01T06:07:00.000-07:00

$mysql -h hostname -u username --password=password

Reading .gz file

2008-08-01T05:57:00.000-07:00

$zcat access-443-*2008* | grep ptb

Linux System Administrator Resources

PERL SOAP Programming Tutorial

What Is SOAP?

SOAPing Up

Carving A Quick SOAP Server

What's Happening?

Seeing the SOAP Light

Network Security Scan

Configure DHCP with LDAP

Look at Black listed IPs

How to unregister/register System from RedHat Satellite Server

How to sign your custom RPM package with GPG Key

Problems && Solutions

What is running on port?

View actual physical memory usage on Linux

Passwordless ssh login

Keeping a Log Of Daily Network Traffic for ADSL or Dedicated Remote Linux Server

Step # 1: Install vnstat

Step # 2: Enable vnstat

Step # 3 View statistics

Linux display bandwidth usage on network interface by host

Restricting Weak SSL Ciphers, F5 BigIP

v9.x Software

Using the GUI

Using the CLI

nmap : scan a subnet for active IPs

To test packet lost

Generating a syslog message

MySQL: show disk space occupied by database

rpmdb: Lock table is out of available locker entries

rpmdb: Lock table is out of available locker entries

Find out who are recently logged on to your linux system

PHP + LDAP Tutorial

Installing kernel-debuginfo on RHEL 5.2

Finding Version of linux installed

Starting virtual server in a single user mode

Displaying Total hard disk size (in Linux)

[root@test4 ~]# fdisk -l | grep DiskDisk /dev/hda: 60.0 GB, 60022480896 bytesDisk /dev/hdb: 200.0 GB, 200049647616 bytes

XEN Virtualization Tutorial

RFC Search URL

System Configuration

Network Related Tools

Nessus -> Security Scanner

MIB for Dell Server

Network speed test applications references

I worked on

Blogging softwares/CMS

Creating test file

SNMP Tutorial Links

RHEL Administrator Guide References

Life will be really easy if such .........................

Personnel

Tutorial Links

Applications

Environment Variables in Linux

How do you know which startup script is responsible for TCP port 111?

To verify whether process is running or not

Connecting MySql Remotely

Reading .gz file

[root@test4 ~]# fdisk -l | grep Disk
Disk /dev/hda: 60.0 GB, 60022480896 bytes
Disk /dev/hdb: 200.0 GB, 200049647616 bytes