[CentOS] Paranoid Firewalling

Alex White ethericalzen at gmail.com
Thu Sep 8 13:41:57 UTC 2005

Kirk Bocek wrote:
> No! It's my secret! Bu-Wa-Ha-Ha! (or however that's spelled...)
> Okay, you forced it out of me...
> http://linuxmafia.com/pub/linux/security/ssh-dictionary-attack-blacklist
> :)
> Sam Drinkard wrote:
>> Kirk,
>>    If you don't mind, could you let me know where that script is?  I'm 
>> seeing the same thing -- kiddies trying to log in.  I use something 
>> similar, but manual entry on my mail server that is in a co-lo site 
>> running FreeBSD.  Here at home, I thought I'd be pretty well protected 
>> behind the router, but I have to have the ssh port open, and I'm 
>> seeing hundreds of attempts.
>> Thanks...
>> Sam
>> Kirk Bocek wrote:
>>> Good question Alex. However, I've never studied the scripts that 
>>> 'script kiddies' use and so have no answer.
>>> Part of what has prompted this change is the recent surge of 
>>> brute-force password attacks. From the timing of the password 
>>> attempts, it's clear that these are script driven.
>>> I found a perl script that watches for failed logins. After a 
>>> configurable number, the script enters the IP address into 
>>> /etc/hosts.deny. After a configurable number of days, the script then 
>>> removes the IP address.
>>> What I see in /var/log/secure is a whole series of 'Invalid user' 
>>> messages followed by 'Failed password for invalid user' messages. 
>>> These will then, because of the script, be terminated by a 'refused 
>>> connect from' message when the address is entered into hosts.deny.
>>> My point in all this is that I only ever see *one* 'refused connect' 
>>> message. So at least for this script, it gives up when it can't 
>>> connect anymore.
>>> Kirk Bocek

Thanks for that linkage. And your previous explanation of what you 
were seeing. Sorry I've been ill so couldnt' check the list until 
today. Really appreciate it.



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