Modify ip-tables directly in ubuntu

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

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

Red Hat Linux cheat sheet commands examples RHEL

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

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

shutdown ubuntu linux

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

OR

$ sudo shutdown -h 0

How do I shutdown compute at specific time?

To shutdown computer at 6:45pm, enter:

. . . → Read More: shutdown ubuntu linux

x11vnc was unable to open the X DISPLAY

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

freebsd find

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

vmware unix

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