To modify ip-tables directly in ubuntu
First save off your current config:
$ sudo -s $ iptables-save > /root/working.iptables.rules
$ iptables-save > /root/working.iptables.rules.to.modify
At this point you can modify the file. Once your are satisfied restore it
# iptables-restore < /root/working.iptables.rules.to.modify
Configure postfix with Gmail via Webmin
This assumes the user has webmin installed and understands how to log in and use it. (Usually bring it up in a browser at https://localhost:10000 )
Make sure that postfix is installed. In Webmin this is done by going to “System”, “Software Packages” then clicking on “Package from APT” and . . . → Read More: Configure postfix with Gmail via Webmin
Useful Linux Commands (Red Hat)
(http://www.cse.buffalo.edu/~eisner/DLW) Revised 3/1/2000
Getting information man commandname display the manual page for a particular command named commandname man -S sectionnumber commandname display the manual page under a specific section numbered sectionnumber for the command named commandname. Sometimes the same command will exist in more than one section. man alone will . . . → Read More: Red Hat Linux cheat sheet commands examples RHEL
Add Public SSH Key to Remote Server in a Single Command From HowToGeek
If you want to setup SSH keys to allow logging in without a password, you can do so with a single command.
The first thing you’ll need to do is make sure you’ve run the keygen command to generate the keys:
ssh-keygen . . . → Read More: Add Public SSH Key to Remote Server in a Single Command
How do I use shutdown command?
The shutdown command can be used to turn off or reboot a computer. Type the command as follows to shutdown server / computer immediately:
$ sudo shutdown -h now
$ sudo shutdown -h 0
How do I shutdown compute at specific time?
To shutdown computer at 6:45pm, enter:
. . . → Read More: shutdown ubuntu linux
Having trouble getting x11vnc working?
Here’s the error:
root@qaubutu:/etc/X11/gdm# x11vnc -forever -usepw -httpdir /usr/share/vnc-java/ -httpport 5800 -auth /var/gdm/:0.Xauth 06/10/2010 16:28:21 *************************************** 06/10/2010 16:28:21 *** XOpenDisplay failed (:0) *** x11vnc was unable to open the X DISPLAY: “:0″, it cannot continue. *** There may be “Xlib:” error messages above with details about the failure.
You must . . . → Read More: x11vnc was unable to open the X DISPLAY
How to find files, programs, etc using freebsd
The locate command is good for finding files and directories. Enter something similar to:
locate someprogram | more
If that doesn’t work, perhaps try the whereis or find commands:
whereis someprogram | more find / -name “someprogram*”
For variations on these commands, you can type:
man locate . . . → Read More: freebsd find
A great place to find vmware virtual machines for freebsd, ubuntu, cent os, red hat linux (RHEL), Linux Mint, etc is over at bagside’s virtual appliance repository
here’s what they offer:
Virtual Appliance Repository.
This site is dedicated to virtual appliances that we build for you to use FREE of charge (except for Windows . . . → Read More: vmware unix