[asterisk-users] Asterisk SIP attacks and sshguard

[Jim Dickenson]

I do not have log examples to provide but do have info about other issues.

There is a nocolor option in asterisk.conf that can turn off color.

logger.conf has a provision to use syslog directly.
-- 
Jim Dickenson
mailto:dickenson at cfmc.com

CfMC
http://www.cfmc.com/



On Dec 9, 2010, at 5:57 AM, Joe Greco wrote:

> Hello,
> 
> We had been seeing SIP-guessing attacks on our Asterisk server here.
> 
> While it wasn't that hard to write a once-a-minute cron job to spank
> the lusers, that runs once a minute and creates little spikes in the
> usage and I/O graphs, and is slower to respond than I'd really prefer.
> I felt that it'd be much cooler to get something more comprehensive 
> put together.  We don't use fail2ban because I don't like having to 
> install python.
> 
> sshguard is a high-performance compiled C application that can run
> off a log file or a pipe from syslogd to sshguard, meaning that it
> can respond a lot more quickly than once a minute, and works with
> very modest overhead on the host system.  It also has features such
> as touchiness, so that it can get tougher on a miscreant as time goes
> on; my own shell script is naive in that once it passes a threshold,
> there's just a permanent rule generated.  This worries me if I ever
> have a situation where a legitimate remote client gets messed up and
> tries the wrong password or something like that; sshguard does a much
> nicer job in this regard.
> 
> In any case, my initial attempts to create rules for sshguard didn't
> work right, quite possibly because I don't often work in LEX/YACC.
> I submitted a request to the sshguard guys suggesting new rules.
> 
> http://www.sshguard.net/support/submission/detail/49ce7182028d8b6f3e3d/
> 
> and on their mailing list, a little more:
> 
> http://sourceforge.net/mailarchive/forum.php?thread_name=F4E10075-5D93-43B4-B73A-1FD217BE130D%40sshguard.net&forum_name=sshguard-users
> 
> In particular, they're looking for log examples of some of those 
> messages, but I have no idea how to generate the conditions that would
> cause these messages.  I'm also not sure if there's a way to disable
> color codes in the Asterisk log files; we log indirectly via BSD's
> "logger"
> 
> # asterisk -vvv 2>&1 | logger -t asterisk
> 
> so it may be thinking that the console is color-capable.  We use this
> method because this forces them through the syslog mechanism; we need 
> that for centralized logging, and it's handy for things like sshguard
> too.
> 
> Specifically looking for examples of (or how to generate)
> 
> 1)	.*No registration for peer '.*' (from <HOST>)
> 2)	.*Host <HOST> failed MD5 authentication for '.*' (.*)
> 3)	.*Failed to authenticate user .*@<HOST>.*
> 
> If anyone who is more familiar with the attacks or how to generate
> these messages would give me some assistance, or chime in on the
> sshguard-users list, that'd be most appreciated.
> 
> Thanks.
> 
> ... JG
> -- 
> Joe Greco - sol.net Network Services - Milwaukee, WI - http://www.sol.net
> "We call it the 'one bite at the apple' rule. Give me one chance [and] then I
> won't contact you again." - Direct Marketing Ass'n position on e-mail spam(CNN)
> With 24 million small businesses in the US alone, that's way too many apples.
> 
> -- 
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