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

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

Linux find large files

How do you find large files or directories on your disk in freebsd, unix, linux ? Linux find large files examples; find large files on your disk in *nix.

All *nix systems List total size of each directory/file at current path level du -sk * | sort -rn | head

Example output:

[root@centos6 /]# du . . . → Read More: Linux find large files

Freeware: TrueCrypt Hard Disk Encryption

TrueCrypt is by far my favorite hard disk encryption program.  It works on Windows, Mac, Linux, etc. and is open source.

Main Features: Creates a virtual encrypted disk within a file and mounts it as a real disk. Encrypts an entire partition or storage device such as USB flash drive or hard drive. Encrypts a partition or drive . . . → Read More: Freeware: TrueCrypt Hard Disk Encryption