Date: Sun, 22 May 2005 20:31:38 -0400 (EDT) From: Francisco Reyes <lists@natserv.com> To: Chris <racerx@makeworld.com> Cc: John DeStefano <john.destefano@gmail.com>, Jerry Bell <jbell@stelesys.com>, freebsd-questions@freebsd.org Subject: Re: securing SSH, FBSD systems Message-ID: <20050522202535.K29197@zoraida.natserv.net> In-Reply-To: <4290EEB4.9070502@makeworld.com> References: <f2160e0d05052205454e6071d5@mail.gmail.com> <1368.24.99.220.144.1116792799.squirrel@24.99.220.144> <4290EEB4.9070502@makeworld.com>
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On Sun, 22 May 2005, Chris wrote: > 5. (and my favorite) If running IPFW, use something like this if you > don't need ssh open to the whole of the internet. narrow it down to a > range of IP's you need. 6. Don't use passwords at all, but use keys. Not always possible though, but possibly one of the better methods. I personally use a combo 1- Use an AllowUsers clause 2- Every time I see script kiddies I black hole their IPs. I black hole them not only because of ssh, but because, just as they tried to attack ssh the same IPs may try other attacks. I try and stay up to date in patches, but it can not hurt to block known compromised/hacker machines. The IPs can be listed either in the firewall or using route add -host <hacker ip> 127.0.0.1 -blackhole I was told that this method of blackholing was more efficient when using a long list of IPs becaues IPFW looks at a linear list while the route list was some sort of tree which is more efficient to search. Over time.. my list of blackholed IPs is 300+ and growing. Every week I add anywhere from 2 to 10 new IPs. :-( Besides ssh I also look for machines trying to attack the web server.. ie a machine looking for files in c:\winnt or any other window directory is a sure sign of a compromised wmachine ith a virus/worm trying to infect more machines.
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