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bye bye messages from ssh attempts

Hi All,

This is really just out of curiosity, I get loads of messages which look something like;
   Received disconnect from 129.1.64.81: 11: Bye Bye

Now I'm happy I'm OK and I have denyhosts enabled and secure passwords etc etc
I was wondering what is used to generate the "Bye Bye" message...

Anyone know?
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jools
Asked:
jools
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1 Solution
 
tl121000Commented:
These as you know are hacking attempts, since SSH is a well known port (22).
you can tighten your firewall to allow only valid users
or
check this out...
http://www.it-slav.net/blogs/?p=183
 
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Dave HoweSoftware and Hardware EngineerCommented:
sadly, its pretty common - one of the "common currency" ssh haxxor scripts uses that disconnect string, and usually tries to log in as guest/guest or test/test before trying a brute force attack.

Each entry should *also* have a number in square brackets, which is the process ID - once you see the byebye, you can use that number with grep to locate any other records in the log for the same process ID - its also worth grepping on the IP address given, to see if there are any other threads that share that IP.

problematic lines will be something like "failed password" - showing attempts to log in.
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tl121000Commented:
If you do not have the rights to configure your FW, you can also configure the hosts.allow file to minimize these occurences...
 
Please refer to these articles and threads to figure out the best way to resolve your problem (or at least minimize it).
http://closedsrc.org/_static/dn-articles/hosts_allow.html
http://lists.freebsd.org/pipermail/freebsd-questions/2006-May/122583.html
 
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Dave HoweSoftware and Hardware EngineerCommented:
really, its just background noise - I did a bit of checking, and of the three scripts I could find that left this trace in the log, they did so by use of a freeware ssh library called "libssh" (logically enough) - for which this is the default disconnect string.

if you *really* want security from ssh, disallow password logins entirely and require use of a client rsa or dsa key to gain access.
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tl121000Commented:
DaveHowe,
I agree with you about background noise, but if there is a particular IP address that is always attempting...  why not block it out completely and minimize a potential  hacking oppurtunity all together.
T
 
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joolsAuthor Commented:
Thanks Dave,

So if the message is logged as bye bye I can almost guarantee it is a hack attempt by someone using a "haxxor script" rather than someone making a mistake and guessing the address wrong.

Thats great.... I've been hit a lot by the ip address above which seems to belong to an educational establishment in Ohio USA. I may, if it continues, get in touch with their abuse account to see if they can have a word in the offenders shell-like or perhaps shut down the offending server if it's been compromised.

As I said before, I'm happy my setup is secure, I just wondered what generated the Bye Bye message in the logs.
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joolsAuthor Commented:
Dave,

You mentioned in http:#a24122384 you found three scripts, do you have the names, I'd like to do a bit more digging around.

I've been logging the connections using wireshark and netcat.

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Dave HoweSoftware and Hardware EngineerCommented:
one was from 'haita team'  -  sshf.c - and another was sshbrute.c from 'lizard', but which credits haita team for some code. the third was a scanning module for metasploit, but as I say, the commonality is use of http://0xbadc0de.be/wiki/ (not to be confused with http://www.libssh2.org/ which has a similar name)
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Dave HoweSoftware and Hardware EngineerCommented:
this would appear to be applicable too:
http://it.slashdot.org/article.pl?sid=09/04/12/2110257
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joolsAuthor Commented:
Thanks Dave, all the  comments have been most helpful
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