Noticed while looking at the source (to see the point of ssh-ddos).
POSSIBLE BREAK-IN ATTEMPT - sounds scary? But keep reading
the message. It's not a login failure. It's a warning about
reverse-DNS. The login can still succeed, and if it _does_ fail,
that will be logged as normal.
<exhibit n="1">
Jul 9 05:43:00 brick sshd[18971]: Address 200.41.233.234 maps to host234.advance.com.
ar, but this does not map back to the address - POSSIBLE BREAK-IN ATTEMPT!
Jul 9 05:43:00 brick sshd[18971]: Invalid user html from 200.41.233.234
</exhibit>
The problem (in my mind) is that some users are stuck with bad dns.
The warning won't stop them from logging in. I'm pretty sure they can't
even see it. But when they exceed a threshold number of logins -
which could be all successful logins - fail2ban will trigger.
fail2ban shouldn't adding additional checks to successful logins
- it goes against the name fail2ban :)
- the first X "POSSIBLE BREAK-IN ATTEMPT"s would be permitted anyway
- if you want to ban bad DNS, the right way is PARANOID in /etc/hosts.deny
I've checked the source of OpenSSH, and this will only affect the
reverse-DNS error. (I won't be offended if you want to check
for yourself though ;)
<exhibit n="2">
$ grep -r -h -C1 'ATTEMPT' openssh-5.5p1/
logit("reverse mapping checking getaddrinfo for %.700s "
"[%s] failed - POSSIBLE BREAK-IN ATTEMPT!", name, ntop);
return xstrdup(ntop);
--
logit("Address %.100s maps to %.600s, but this does not "
"map back to the address - POSSIBLE BREAK-IN ATTEMPT!",
ntop, name);
$
</exhibit>
* gh-magicrhesus/master:
Add the INCLUDE section to use __pid_re feature
Disable asterisk jail by default
Change jail for asterisk, add support for SIP and SIP-TLS on TCP and UDP ports
Change NOTICE by NOTICE%(__pid_re)s
Remove custom bantime
Add sample log file for asterisk
Add $ at the end of the failregex
Add asterisk support
Conflicts:
config/jail.conf -- placed asterisk jails before recidive and added blank lines after the jail headers
although %m-%d-%Y is ambioius with %d-%m-%Y it comes after so it should not
be too dangerous (i.e. in upcoming days having smth like 02-01 should work as before matching
first one first) and proper fix to select between the two should follow some time
soon