Date: Fri, 2 Oct 2009 16:32:24 +0100 From: =?ISO-8859-1?B?SXN0duFu?= <leccine@gmail.com> To: johnea <me@johnea.net> Cc: freebsd-security@freebsd.org Subject: Re: openssh concerns Message-ID: <b8592ed80910020832r6ba8ab86s4b0db5af0a3766db@mail.gmail.com> In-Reply-To: <4AC61C0B.3050704@johnea.net> References: <4AC545C3.9020608@johnea.net> <19141.20047.694147.865710@hergotha.csail.mit.edu> <4AC61C0B.3050704@johnea.net>
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Protect against simple DNS spoofing attacks by checking that the... So if the ssh bruteforce is coming from a properly setup DNS host it is ok :)))) On Fri, Oct 2, 2009 at 4:28 PM, johnea <me@johnea.net> wrote: > Garrett Wollman wrote: > >> <<On Thu, 01 Oct 2009 17:13:55 -0700, johnea <me@johnea.net> said: >> >> The thing that concerned me is an entry I saw in netstat showing >>> my system connecting back to a machine that was attempting to log >>> in to ssh. >>> >> >> Does the ssh server establish a socket to a client attempting login? >>> >> >> The SSH protocol does not, but you appear to be using "TCP wrappers" >> (/etc/hosts.allow) configured in such a way that it make an IDENT >> protocol request back to the originating server. This is rarely >> likely to do anything useful and should probably be disabled. >> >> tcp4 0 0 atom.60448 host154.advance.com.ar.auth >>> TIME_WAIT >>> >> >> "auth" is the port number used by the IDENT protocol. >> >> -GAWollman >> > > Thank You to everyone who responded! > > In fact I did discover these lines in hosts.allow: > > 31-# Protect against simple DNS spoofing attacks by checking that the > 32-# forward and reverse records for the remote host match. If a mismatch > 33-# occurs, access is denied, and any positive ident response within > 34-# 20 seconds is logged. No protection is afforded against DNS poisoning, > 35-# IP spoofing or more complicated attacks. Hosts with no reverse DNS > 36-# pass this rule. > 37:ALL : PARANOID : RFC931 20 : deny > > This is what was generating the auth protocol socket. > > I've disabled it to prevent the establishment of the auth socket to hosts > who are attempting to breakin. > > Per another suggestion I also intend to change the port for ssh to a > non-standard number (after synchronizing with the users of course 8-) > > Maybe I'm a little paranoid, but after watching the level of spam ever > increasing over the last 5 years, and more and more people moving to > big (monopolistic?) service providers like google and hotmail. I've > wondered if these big corporate service providers don't tolerate the > spam level in order to prevent anyone who doesn't have a building full > of IT staff from running their own mail servers. > > Perhaps with the help of people like those on this list, the internet > won't have to be abandoned by independents? > > Thanks again to everyone! > > johnea > _______________________________________________ > freebsd-security@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-security > To unsubscribe, send any mail to "freebsd-security-unsubscribe@freebsd.org > " > -- the sun shines for all
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