Sys Admin Guides, How To's, etc by Marios Maravelias

A quick and usefull command for checking if a server is under ddos is:

netstat -anp |grep ‘tcp\|udp’ | awk ‘{print $5}’ | cut -d: -f1 | sort | uniq -c | sort -n

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It has become apparent that spammers are getting even smarter than we take them for. Rather than abuse open relays, which are almost non-existent, these scum-of-the-earth ‘traders’ are now abusing contact forms.

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Scope

Some idiot created a SSH worm that uses a dictionary attack to try to log into a computer over port 22. The worm tries to set up shop on your computer and tries to find the next vulnerable computer. This clogs up networks with bazillions of SSH login attempts.

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Read the fine article here.

Use mod_rewrite and .htaccess file to block user agent libwww-perl. Open your .htaccess file and add rule as follows:

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Not only do I block all accesses from libwww-perl, I also log what they were looking for which turns up an amazing amount of botnet hits on a daily basis just randomly hitting websites trying to find a way inside.

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