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Q. I can measure network throughput and packet loss using standard UNIX / Linux command line utilities. How do I find out the lateceny and throughput of a web server like Apache under Linux?
A. You need to use the program called httping. It allows you to measure the latency of a webserver and the throughput.
Task: Ping the webserver on host www.cyberciti.biz
Use the following command for measuring the latency. Press CTRL+c to exit the program. It will display a summary of what was measured.
$ httping -g http://www.cyberciti.biz
PING www.cyberciti.biz:80 (http://www.cyberciti.biz): connected to www.cyberciti.biz:80, seq=0 time=981.08 ms connected to www.cyberciti.biz:80, seq=1 time=709.92 ms connected to www.cyberciti.biz:80, seq=2 time=1072.02 ms connected to www.cyberciti.biz:80, seq=3 time=903.81 ms connected to www.cyberciti.biz:80, seq=4 time=607.84 ms connected to www.cyberciti.biz:80, seq=5 time=660.01 ms connected to www.cyberciti.biz:80, seq=6 time=730.12 ms connected to www.cyberciti.biz:80, seq=7 time=781.49 ms
The -g url option use selects the url to probe / ping. You can also specify the port with -p port option:
$ httping -g http://www.cyberciti.biz -p 81
You can also connect using SSL, for this to work you need to give a https url or a 443 portnumber:
$ httping -l -g https://www.cyberciti.biz
$ httping -g http://www.cyberciti.biz -p 443
Task: Measure throughput of a webserver
The -G option force GET request instead of a HEAD request – this means that also the complete page/file must be transferred. You also need to pass the -b option with -G option to get the transferspeed (in KB/s).
$ httping -Gbg http://www.cyberciti.biz/
PING www.cyberciti.biz:80 (http://www.cyberciti.biz/): connected to www.cyberciti.biz:80, seq=0 time=1738.39 ms 22KB/s connected to www.cyberciti.biz:80, seq=1 time=1650.19 ms 20KB/s connected to www.cyberciti.biz:80, seq=2 time=1759.65 ms 17KB/s connected to www.cyberciti.biz:80, seq=3 time=1589.98 ms 21KB/s connected to www.cyberciti.biz:80, seq=4 time=3709.87 ms 6KB/s connected to www.cyberciti.biz:80, seq=5 time=3329.69 ms 7KB/s .... ..... --- http://www.cyberciti.biz/ ping statistics --- 53 connects, 53 ok, 0.00% failed round-trip min/avg/max = 1451.9/2013.6/11656.0 ms Transfer speed: min/avg/max = 6/19/24 KB
Please note above in above command youâ€™re no longer measuring the latency!
You can also pass -X option with -G to show the amount of data transferred (excluding the headers):
$ httping -XGbg http://www.cyberciti.biz/
PING www.cyberciti.biz:80 (http://www.cyberciti.biz/): connected to www.cyberciti.biz:80, seq=0 time=1576.11 ms 22KB/s 19KB connected to www.cyberciti.biz:80, seq=1 time=2620.26 ms 9KB/s 19KB connected to www.cyberciti.biz:80, seq=2 time=1507.69 ms 23KB/s 19KB connected to www.cyberciti.biz:80, seq=3 time=1522.08 ms 24KB/s 19KB connected to www.cyberciti.biz:80, seq=4 time=1533.68 ms 23KB/s 19KB connected to www.cyberciti.biz:80, seq=5 time=1581.92 ms 21KB/s 19KB connected to www.cyberciti.biz:80, seq=6 time=1512.06 ms 24KB/s 19KB --- http://www.cyberciti.biz/ ping statistics --- 7 connects, 7 ok, 0.00% failed round-trip min/avg/max = 1507.7/1693.4/2620.3 ms Transfer speed: min/avg/max = 9/21/24 KB
Test remote server CPU
The -B option along with -G option ask the HTTP server to compress the returned data – this will reduce the influence of the bandwidth of your connection while increasing the influence of the processorpower of the HTTP server.
$ httping -BGg http://www.cyberciti.biz/
The -f option used to flood ping i.e. do not sit idle between each ping but ping as fast as the computer and network allow you to (don’t run this on production or 3rd party servers):
$ httping -fg http://www.cyberciti.biz/
Q. How do I tunnel X Windows Securely over SSH? I’d like to run X program on my remote Linux server and get back display to Laptop computer connected by high speed internet?
A. A tunneling protocol is a network protocol which encapsulates a payload protocol, acting as a payload protocol. Reasons to tunnel include carrying a payload over an incompatible delivery network, or to provide a secure path through an untrusted network.
SSH is frequently used to tunnel insecure traffic over the Internet in a secure way. Simply type the following command:
$ ssh -X email@example.com
$ ssh -X firstname.lastname@example.org
You can requests compression of all data to improve up user experience (good for a low speed link such as wan link) using -c option:
$ ssh -c -X email@example.com
Once logged in type any X windows program name such as:
$ xeys &
$ oowriter &
To start kde type:
$ startkde &
To start default desktop type:
Q. How do I start or stop X.Org from a command prompt?
A. X.org is open-source implementation of the X11 system. It is an open source X11-based desktop infrastructure. Xorg provides an interface between your hardware and the graphical software you want to run. Besides that, Xorg is also fully network-aware, meaning you are able to run an application on one system while viewing it on a different one.
Start X.Org Server
There are two ways, just type startx:
Alternatively, run init script such as /etc/init.d/gdm
# /etc/init.d/gdm start
$ sudo /etc/init.d/gdm start
Ctrl+Alt+Backspace – to stop server
Press Ctrl+Alt+Backspace to immediately kill the server – no questions asked.
Agian, you can use init script to stop session:
# /etc/init.d/gdm stop
$ sudo /etc/init.d/gdm stop
Q. How do I change the runlevel for a Linux server without rebooting my server? I am using Gentoo Linux.
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