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Anti DDOS
Takes IP from web logs and pipes to iptables, use grep to white list IPs.. use if a particular file is getting requested by many different addresses. Sure, its already down pipe and you bandwidth may suffer but that isnt the concern. This one liner saved me from all the traffic hitting the server a second time, reconfigure your system so your system will work like blog-post-1.php or the similar so legitimate users can continue working while the botnet kills itself.

spawn shell listener service with nc

purge all packages marked with 'rc'
After you install/remove lots of packages, there are many packages marked with 'rc'. This script help you to purge these packages, it will save some spaces from your disk.

Harder, Faster, Stronger SSH clients
We force IPv4, compress the stream, specify the cypher stream to be Blowfish. I suppose you could use aes256-ctr as well for cypher spec. I'm of course leaving out things like master control sessions and such as that may not be available on your shell although that would speed things up as well.

Search trought pidgin's conversation logs for "searchterm", and output the result.
will search trought pidgin conversation logs for "searchterm", and output them stripping the html tags. The "sed" command is optionnal if your logs are stored in plain text format.

delete duplicate lines from a file and keep the order of the other lines
i wanted to delete all duplicate lines from .bash_history and keep the order of the other lines. the command cat's the file and adds line numbers, then sorts by the second column. afterwards uniq omits repeated lines, but skips the first field (the line number). then it sorts by the line numbers and at the end cuts the numbers off.

Which processes are listening on a specific port (e.g. port 80)
swap out "80" for your port of interest. Can use port number or named ports e.g. "http"

List bash functions defined in .bash_profile or .bashrc
typeset command gives to stdout all the functions defined in a bash session, -f and -F switches are for: all functions names with body (-f) and all functions names only (-F).

Pipe STDOUT to vim
The hyphen tells vim to open from STDOUT - saves having to create temporary files.

check open ports without netstat or lsof


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