[165346] in North American Network Operators' Group
Re: Parsing Syslog and Acting on it, using other input too
daemon@ATHENA.MIT.EDU (Shawn Wilson)
Fri Aug 30 08:56:38 2013
In-Reply-To: <CAL9jLaZk6E3xd5ZUpi5-MMDRgAEd8g4z0g8=ob6HNTvBs-36NQ@mail.gmail.com>
From: Shawn Wilson <ag4ve.us@gmail.com>
Date: Fri, 30 Aug 2013 08:55:52 -0400
To: Christopher Morrow <morrowc.lists@gmail.com>,
Don Wilder <don.wilder@gmail.com>
Cc: NANOG list <nanog@nanog.org>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
Christopher Morrow <morrowc.lists@gmail.com> wrote:
>On Thu, Aug 29, 2013 at 10:50 AM, Don Wilder <don.wilder@gmail.com>
>wrote:
>> I wrote a script in Linux that watches for unauthorized login
>attempts and
>> adds the ip address to the blocked list in my firewall. You might
>want to
>> search sourceforge for a DYN Firewall and modify it from there.
>>
>
>because fail2ban was too hard to install? or because you just wanted
>to test yourself?
Actually I did the same. I use ipset lists (generally with a timeout) and take a regex or two and black / white list from a YAML file and just take (possibly multiple inputs) from piping tail -F. I also store addresses for future reference (by the script or otherwise).
This is quite maintainable as I can look at a list of people who have attacked the mail server and compare it to web attacks. Each process is a different type of service (different config file) and probably a different ipset. Due to ipset not actually doing anything until I make an iptables rule for it, I can run my script in a test mode (by default) and just see what happens (check it's logs and the ipset list it generates). I haven't found the need for this yet but I can use cymru to look up how big their net is (see geocidr for an example of how to do this in perl) and use a hash:net ipset type and cover a whole net.
Basically what I'm saying in doing it this way is quite expandable and isn't very hard and I can do tons of stuff that fail2ban can't (I don't think - it's been a while since I looked).
