The apf firewall with bfd brute force detection will parse your
/var/log/secure file and insert a block on any offending IP that tries
repeated attacks according to your configuration. This checking is done
every minute and it can email you a warning. I get these a few times a
day and currently have almost 800 IPs blocked.
Then of course if someone in a company that uses your system wants to make
life difficult for colleagues, they can always promote a block but since
you can keep the emails for ever and they list all the accounts tried, you
have the evidence...:-)
Have a look at http://www.r-fx.org and follow the links to apf and bfd.
The software is available under GPL but there is also a service that can
be purchased at reasonable rates.
Best wishes
John
John Logsdon "Try to make things as simple
Quantex Research Ltd, Manchester UK as possible but not simpler"
j.logsdon@xxxxxxxxxxxxxxxxxxxx a.einstein@xxxxxxxxxxxxxx
+44(0)161 445 4951/G:+44(0)7717758675 www.quantex-research.com
On Fri, 30 Dec 2005, John Hinton wrote:
> John Hinton wrote:
>
> > Had two nameservers crash in the last few hours... This 'never'
> > happens! On the console was
> >
> > sent an invalid ICMP type 3, code 3 error to a broadcast:
> > 255.255.255.255 on eth0
> >
> > sent an invalid ICMP type 3, code 3 error to a broadcast:
> > 255.255.254.255 on eth0
> >
> > with the IP address of the offender? in front of that line. Any ideas?
> >
> > Best,
> > John Hinton
>
> And a bit more info.
>
> Seems that maybe it just happened to be nameservers. Found this in the
> logs repeated over and over for thousands of lines.
>
> Dec 30 16:00:24 cavebear vsftpd(pam_unix)[29588]: check pass; user unknown
> Dec 30 16:00:24 cavebear vsftpd(pam_unix)[29588]: authentication
> failure; logname= uid=0 euid=0 tty= ruser= rhost=210.95.162.215
> Dec 30 16:00:26 cavebear vsftpd(pam_unix)[29590]: check pass; user unknown
> Dec 30 16:00:26 cavebear vsftpd(pam_unix)[29590]: authentication
> failure; logname= uid=0 euid=0 tty= ruser= rhost=210.95.162.215
> Dec 30 16:00:26 cavebear vsftpd(pam_unix)[29588]: check pass; user unknown
> Dec 30 16:00:26 cavebear vsftpd(pam_unix)[29588]: authentication
> failure; logname= uid=0 euid=0 tty= ruser= rhost=210.95.162.215
> Dec 30 16:00:29 cavebear vsftpd(pam_unix)[29588]: check pass; user unknown
> Dec 30 16:00:29 cavebear vsftpd(pam_unix)[29588]: authentication
> failure; logname= uid=0 euid=0 tty= ruser= rhost=210.95.162.215
> Dec 30 16:00:29 cavebear vsftpd(pam_unix)[29590]: check pass; user unknown
> Dec 30 16:00:29 cavebear vsftpd(pam_unix)[29590]: authentication
> failure; logname= uid=0 euid=0 tty= ruser= rhost=210.95.162.215
> Dec 30 16:00:32 cavebear vsftpd(pam_unix)[29588]: check pass; user unknown
> Dec 30 16:00:32 cavebear vsftpd(pam_unix)[29588]: authentication
> failure; logname= uid=0 euid=0 tty= ruser= rhost=210.95.162.215
> Dec 30 16:00:32 cavebear vsftpd(pam_unix)[29590]: check pass; user unknown
> Dec 30 16:00:32 cavebear vsftpd(pam_unix)[29590]: authentication
> failure; logname= uid=0 euid=0 tty= ruser= rhost=210.95.162.215
> Dec 30 16:00:35 cavebear vsftpd(pam_unix)[29588]: check pass; user unknown
> Dec 30 16:00:35 cavebear vsftpd(pam_unix)[29588]: authentication
> failure; logname= uid=0 euid=0 tty= ruser= rhost=210.95.162.215
> Dec 30 16:00:35 cavebear vsftpd(pam_unix)[29590]: check pass; user unknown
> Dec 30 16:00:35 cavebear vsftpd(pam_unix)[29590]: authentication
> failure; logname= uid=0 euid=0 tty= ruser= rhost=210.95.162.215
> Dec 30 16:00:37 cavebear vsftpd(pam_unix)[29588]: check pass; user unknown
> Dec 30 16:00:37 cavebear vsftpd(pam_unix)[29588]: authentication
> failure; logname= uid=0 euid=0 tty= ruser= rhost=210.95.162.215
> Dec 30 16:00:38 cavebear vsftpd(pam_unix)[29590]: check pass; user unknown
> Dec 30 16:00:38 cavebear vsftpd(pam_unix)[29590]: authentication
> failure; logname= uid=0 euid=0 tty= ruser= rhost=210.95.162.215
> Dec 30 16:00:40 cavebear vsftpd(pam_unix)[29588]: check pass; user unknown
> Dec 30 16:00:40 cavebear vsftpd(pam_unix)[29588]: authentication
> failure; logname= uid=0 euid=0 tty= ruser= rhost=210.95.162.215
>
> Seems I'm experiencing a DoS against vsftp login. Anybody got a good way
> to limit the number of failed login attempts by one IP address?
>
> Thanks,
> John Hinton
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