I have DenyHosts blocking on failures from FTP and SSH.  I use syslog to
combine the logging of OpenSSH and VSFTP into one log file.  I have  I
plan on writing regex for dovecot logs (POPS and IMAPS server) when I get
some time.  If someone has already done so, please share!  The regex I use
for my combined log file is:

# Match is in two parts.
# Add vsftp: to match log entry.
# Add vsftp regex to match log message. - Ron Nash
# Jul  6 16:52:35 rohan sshd[18061]: [ID 800047 local1.info] Failed
password for invalid user admin from 60.31.195.66 port 32581 ssh2
# Jul  6 16:52:44 rohan vsftpd: [ID 702911 news.warning] Mon Jul  6
16:52:44 2009 [pid 11699] [account] FAIL LOGIN: Client "41.211.226.55"

SSHD_FORMAT_REGEX=.* (sshd.*:|\[sshd\]|vsftpd:) (?P<message>.*)
USERDEF_FAILED_ENTRY_REGEX=\[(?P<user>\S+)\].*FAIL LOGIN.*"(?P<host>\S+)"

I have whitelisted most of the class B subnets our users connect from in
/etc/hosts.allow  Whitelisting prevents the service calls when a user
plugs in a bad username/password into a package that retires often. The
format is "ALL: 123.456.0.0/255.255.0.0" to white list any IP in the
123.456 subnet.

For the other users, I block for an hour on bad attempts.

For root and restricted usernames I block for 5 days.  I've harvested 26
"toxic" usernames that I restrict after 2 attempts to use.

-Ron

> Doh, sorry, I answered for "part 2".  For part 1, you can specify custom
> regex that you could tailor to match other things, but it's far from
> ideal, even apart from it getting quite complicated.  Eg. I want to
> block hosts from failed ssh login attempts quite quickly, but if I had
> the same threshhold on a pop3 server, any of my customers that mistypes
> their username or password is almost guaranteed to be blocked and
> require manual cleanup by the time they call in.
>
>   I only briefly looked at fail2ban a few years ago and I believe it was
> better suited to multiple services, but I've not tried using it.
>
>   You might get by with multiple denyhost instances running, each
> pointing to a seperate config file.  Far from ideal.  Maybe you want to
> contribute this feature to denyhosts, so I can use it, too?   :)
>
> Jesse
>
>
> On Thu, 2009-07-09 at 11:35 -0500, Neil Aggarwal wrote:
>> Hello:
>>
>> > To me, it seems the advantage of Fail2ban is that
>> > it will block more than just SSH attempts.  Does
>> > DenyHosts have that ability?
>>
>> I probably need to clarify this question.
>>
>> There are two parts to blocking an offender:
>> 1. Identification of a hacking attempt
>> 2. Blocking the host the offender used
>>
>> For part 2, it looks like DenyHosts can block
>> individual services or all access to my machine
>> so that is not a problem.
>>
>> I am concerned about part 1.  It looks like DenyHosts
>> only identifies an offender when they attempt an
>> SSH login and fail.  Other types of attacks (Eg: pop3s)
>> will not trigger DenyHosts to block the offender.
>>
>> Is there a way to tell DenyHosts to account for all
>> types of access to a machine?
>>
>> The reason I ask is it seems Fail2ban can take more than
>> SSH failures into account. I like the idea of the
>> synchronization service DenyHosts offers, but it seems
>> Fail2ban will offer more complete protection.
>>
>> Thanks,
>>      Neil
>>
>> --
>> Neil Aggarwal, (281)846-8957, www.JAMMConsulting.com
>> Will your e-commerce site go offline if you have
>> a DB server failure, fiber cut, flood, fire, or other disaster?
>> If so, ask me about our geographically redudant database system.
>>
>>
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> --
> Jesse Norell
> Kentec Communications, Inc.
> [email protected]
>
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