On 03/07/13 09:26, Robert Schetterer wrote:
Am 03.07.2013 04:11, schrieb Stan Hoeppner:
On 7/2/2013 8:32 PM, Professa Dementia wrote:
On 7/2/2013 6:21 PM, John Fawcett wrote:
dnsbl's are a popular method to prevent listed ips from making connections to mta software.
cf. postscreen_dnsbl_sites in postfix
Would it be possible to introduce such a feature in dovecot, so that connections can be denied based on a dnsbl lookup (where the precise dnsbls used are configurable)?
John
Let's back up a bit. This does not seem like a feature that Dovecot needs.
Rather, what problem are you trying to solve? Maybe there is an existing or better way to accomplish it. Based on John's recent thread on postfix-users on the same general subject, I'd guess he's trying to stop rouge/malicious connections.
so perhaps fail2ban might help, or construct something out of syslog and iptables recent, or use dovecot deny etc
http://wiki2.dovecot.org/HowTo/Fail2Ban http://wiki2.dovecot.org/Authentication/RestrictAccess http://wiki2.dovecot.org/PasswordDatabase/ExtraFields/AllowNets
only german, but code should understandable anyway for new coding ideas
http://sys4.de/de/blog/2012/12/28/botnets-mit-rsyslog-und-iptables-recent-mo...
usually fail2ban is enough for brute force pop3/imap, but blocking ips is a problem ever with nat clients
Best Regards MfG Robert Schetterer
Thanks Robert, I saw that article and implemented that in fail2ban to stop repeated hammering attempts on the server from the same clients already rejected by dnsbl in postfix.
I was thinking of extending the mechanism to imap/pop.
John