On 17/06/2014 18:56, Reindl Harald wrote:
Am 17.06.2014 19:43, schrieb Giles Coochey:On 17/06/2014 18:16, Reindl Harald wrote:after having my own dnsbl feeded by a honeypot and even mod_security supports it for webservers i think dovecot sould support the same to prevent dictionary attacks from known bad hosts, in our case that blacklist is 100% trustable and blocks before SMTP-Auth while normal RBL's are after SASL i admit that i am not a C/C++-programmer, but i think doing the DNS request and in case it has a result block any login attemt should be not too complex setup a own honeypot and feed rbldnsd with the sources is quite easy and in case of a own, trustable RBL where no foreigners report somebody by mistake it's relieable and scales well over many machines and services as long services supporting it mod_security: http://blog.inliniac.net/2007/02/23/blocking-comment-spam-using-modsecurity-and-realtime-blacklists/If you have the bllist as a file then you may as well drop with iptables (in Linux) or ipfw (BSD). Use an IP tool for an IP block, not the application. Spamhaus project has a kind of script for this type of thing: http://www.spamhaus.org/faq/section/DROP%20FAQ I'm quite happy to use fail2ban, yes - dovecot has to handle a few failed logins for each blocked IP, but it works for me and pretty much mitigates the attackthat's not the point, to achieve the same as with a RBL you need to manipulate iptables on every machine - the RBL is centrally for HTTP/SMTP and so it makes sense to use it also for IMAP/POP3
Or just do it on the firewall...
additionally you have no log - thats bad with a RBL you have a dedicated log containign much more data than source / target IP and ports
Iptables has a log option.
also i don't want to have fail2ban on every machine, the point of a RBL with a honeypot is that bad machines are blocked for 7 days just beause they touch any unused IP and likely before they even hit the production servers
That's your personal choice.
iptables-rules are managed here also centralized over a lot of machines and i really don't want to marry the honeypot with the iptables
That's specific to your deployment.I don't know how much use such a feature within dovecot would get as there are quite a few specific tools that could accomplish pretty much the same goals of what you're looking for - it is just unfortunate that they don't fit in your own environment.
Perhaps others on the list would have opinions on it. -- Regards, Giles Coochey, CCNP, CCNA, CCNAS NetSecSpec Ltd +44 (0) 8444 780677 +44 (0) 7983 877438 http://www.coochey.net http://www.netsecspec.co.uk gi...@coochey.net
smime.p7s
Description: S/MIME Cryptographic Signature
