Re: [Dovecot] limiting number of incorrect logins per connection
fail2ban will work as soon as dovecot have closed a none-authenticated connection: 3mins-180sec If tarpit delay for auth failures in a connection is set to 15s (which seems to be the default unless i missunderstood) this let an attackers only 12 tries (at most) before IP gets blacklisted by fail2ban... Far enough to circumvent bruteforce and even dictionnary based attacks... unless the attacker has a botnet and uses non agressives retry policy. But in the last case, even if you blacklist IP at first failed tried, you're still vuln to such attacks. regards. Le 26/08/2011 14:22, Felipe Scarel a écrit : Yeah, I had read about half of that thread, and after I sent my mail kept reading and stumbled upon this: (...) using the recent module needs dovecotto close the connection upon authentication failure, as iptables only (normally) comes in to play for new connections (...). So, yeah, my suggestion probably won't work. On Fri, Aug 26, 2011 at 09:15, Felipe Scarelfbsca...@gmail.com wrote: Alex, I've not personally done it (so just speculating here, bear with me) but you can customize Fail2Ban's actions if needed. So, if you can match the attemps through some regex (and since you're seeing them in the logs, that should be quite possible), then you can edit one of the 'actions' to drop the connection forip. I'm just not entirely sure that iptables (or pf, or whatever firewall you've got) can do it to active connections, 'cause that problem hasn't arised for me so far. On Fri, Aug 26, 2011 at 06:14, Alexa...@ahhyes.net wrote: I am happy to recompile if there is no config option. I gather it's in the src/auth dir somewhere in one of the C source files. Just need to be pointed in the right dir. On Fri, 26 Aug 2011 19:07:08 +1000, Alex wrote: 3 minutes! I think that's too long, how can I drop that down to about 45 seconds? On Fri, 26 Aug 2011 11:44:45 +0300, Timo Sirainen wrote: On 26.8.2011, at 10.25, Alex wrote: Running Dovecot 2 on my server. It is regularly getting dictionary auth attacked. What I have noticed is that once connected to a pop3/imap login session, you can send endless incorrect usernames+passwords attempts. This is a problem for me... I use fail2ban to try and stop these script kiddies. The problem is that fail2ban detects the bad auths, firewalls the IP, however, since it's an established session, the attacker can keep authing away... It's only on a subsequent (new) connection that the firewalling will take effect. Umm. If client hasn't managed to log in in 3 minutes, it's disconnected (no matter what it does with the connection). -- http://www.horoa.net attachment: a_chapellon.vcf
[Dovecot] May Dovecot help in users education
inline: horoa_sig.pngattachment: a_chapellon.vcf
Re: [Dovecot] May Dovecot help in users education
Hello, I was wondering if dovecot could help me in my project to smoothly make all my users switch to TLS encrypted POP / IMAP sessions and forget about cleartext. My first idea was to setup dovecot as a POP/IMAP proxy for my mailhosts and ask dovecot to display a warning message or slowdown non TLS sessions. Is there any way to achieve this with dovecot? Does anybody have another idea smoothly force used to switch to TLS? Regards. P.S: double posted because previous was HTML and I've seen some MUA fails to display it properly... sorry will only send raw text now. attachment: a_chapellon.vcf
Re: [Dovecot] May Dovecot help in users education
Le 17/08/2011 16:05, Laurent CARON a écrit : On 17/08/2011 16:00, Alexandre Chapellon wrote: Is there any way to achieve this with dovecot? Does anybody have another idea smoothly force used to switch to TLS? Hi, Maybe by sending them an email with a deadline for the end of clear text auth support ? If they don't amend their setup they'll be unable to retrieve their emails. :)... already tried this in the past and it just don't work... 80% of users never apply changes and prefer getting very angry and call the support. Which is exactly what I want to avoid. Should you want to go the nicer way, you could throttle bandwidth to port 110/143 provided you use those for insecure connections. This sounds better and I though tc could help going that way, but there is nothing informative in going this way. I know what I ask for seems crappy and probably is out of the scope of what dovecot is supposed to do, but this would be temporary and I wanna make sure it is not possible before digging somewhere else. Thanks -- http://www.horoa.net attachment: a_chapellon.vcf
Re: [Dovecot] May Dovecot help in users education
Le 17/08/2011 16:35, Eric Shubert a écrit : On 08/17/2011 07:24 AM, Alexandre Chapellon wrote: Le 17/08/2011 16:05, Laurent CARON a écrit : On 17/08/2011 16:00, Alexandre Chapellon wrote: Is there any way to achieve this with dovecot? Does anybody have another idea smoothly force used to switch to TLS? Hi, Maybe by sending them an email with a deadline for the end of clear text auth support ? If they don't amend their setup they'll be unable to retrieve their emails. :)... already tried this in the past and it just don't work... 80% of users never apply changes and prefer getting very angry and call the support. Which is exactly what I want to avoid. Should you want to go the nicer way, you could throttle bandwidth to port 110/143 provided you use those for insecure connections. This sounds better and I though tc could help going that way, but there is nothing informative in going this way. I know what I ask for seems crappy and probably is out of the scope of what dovecot is supposed to do, but this would be temporary and I wanna make sure it is not possible before digging somewhere else. Thanks I think I would write a script that would glean such accounts from the dovecot log, then send them a message every day instructing them how to turn on TLS in order to quit getting this message. A support line to call for help would be nice for those who have difficulty changing their configuration. I didn't think about that It's quite basic but i like that. Thanks -- http://www.horoa.net attachment: a_chapellon.vcf
[Dovecot] migration scenario
Hello, I'd like to know if anybody have an experience with migrating mailboxes from mirapoint mail system to dovecot? If so how was it done and what were the difficulties? regards.
Re: [Dovecot] migrating to dovecot
Le mardi 29 mars 2011 à 19:04 -0400, Jim Lawson a écrit : Does the proprietary solution allow IMAP access? If so, I would use imapsync. Thanks for answers. Not all the accounts have IMAP enabled, but I guess I could setup some master account with IMAP enabled or even enable IMAP for all users to proceed with migration. But will imapsync keep trac of UIDs so users won't have have duplicated messages or re-download them if they use POP3? Will it preserve flags of messages so read or deleted messages do not appear as new messages? regards. http://www.linux-france.org/prj/imapsync/ Jim On 3/29/11 18:26 , Alexandre Chapellon wrote: Hello, I am trying to setup a migration scenario from an proprietary solution to dovecot IMAP/POP3. Whereas am only at the strating point, things appear quite complicated because of the following reasons: - The proprietary solution uses special/own/proprietary mailbox format (wich is more like maildir but is not maildir) - I don't have direct access to the filesystem where the mails are stored. The best I could do would be a snapshots of the filesystem - I have about 1,5TB of mail data. - Having users to be forced to empty their mailbox before migration or re-download their whole mailbox after migration would be something hard for me to present as a correct option. Am looking for advices that would avoid me loosing time searching in bad directions. Or even point me to a miraculous tool thatdoes all magic while i have a beer :) Best regards. -- horoa: la voie est libre signature.asc Description: This is a digitally signed message part
[Dovecot] migrating to dovecot
Hello, I am trying to setup a migration scenario from an proprietary solution to dovecot IMAP/POP3. Whereas am only at the strating point, things appear quite complicated because of the following reasons: - The proprietary solution uses special/own/proprietary mailbox format (wich is more like maildir but is not maildir) - I don't have direct access to the filesystem where the mails are stored. The best I could do would be a snapshots of the filesystem - I have about 1,5TB of mail data. - Having users to be forced to empty their mailbox before migration or re-download their whole mailbox after migration would be something hard for me to present as a correct option. Am looking for advices that would avoid me loosing time searching in bad directions. Or even point me to a miraculous tool thatdoes all magic while i have a beer :) Best regards. -- horoa: la voie est libre signature.asc Description: This is a digitally signed message part
