Am 18.07.2017 um 21:44 schrieb mj: > Hi all, > > It seems we are under some kind of password guessing attack: > >> Jul 18 21:33:33 auth: Info: >> ldap(username1,103.6.223.61,<W7wLl5xUfABnBt89>): invalid credentials >> (given password: 1q2w3e4r5t) >> Jul 18 21:34:16 auth: Info: >> ldap(username1,221.4.61.180,<89WnmZxUrADdBD20>): invalid credentials >> (given password: 1q2w3e4r5t) >> Jul 18 21:36:13 auth: Info: >> ldap(username2,117.243.180.225,<ESWBoJxUdQB187Th>): invalid >> credentials (given password: 1q2w3e4r) >> Jul 18 21:36:50 auth: Info: >> ldap(username2,58.59.103.230,<j7fQopxUNgA6O2fm>): invalid credentials >> (given password: 1q2w3e4r) >> Jul 18 21:36:56 auth: Info: >> ldap(username4,58.215.13.154,<gtY5o5xUlQA61w2a>): invalid credentials >> (given password: 1q2w3e4r5t) >> Jul 18 21:37:18 auth: Info: >> ldap(username3,220.175.154.205,<lFxppJxUFADcr5rN>): invalid >> credentials (given password: 1q2w3e4r) >> Jul 18 21:37:25 auth: Info: >> ldap(username5,14.142.29.142,<40zopJxUSgAOjh2O>): invalid credentials >> (given password: 1q2w3e4r) >> Jul 18 21:37:27 auth: Info: >> ldap(username4,119.1.98.121,<JDQOpZxUCwB3AWJ5>): invalid credentials >> (given password: 1q2w3e4r5t) >> Jul 18 21:37:54 auth: Info: >> ldap(username3,218.76.156.11,<OMqtppxUMADaTJwL>): invalid credentials >> (given password: 1q2w3e4r) > > Different IPs, different usernames, but all (almost) the same password. > > Any idea what we can do about this?? > > Any advice you could give us would be very much appreciated. > > MJ
perhaps this https://wiki.dovecot.org/HowTo/Fail2Ban or you may adapt this https://sys4.de/de/blog/2015/11/07/abwehr-des-botnets-pushdo-cutwail-ehlo-ylmf-pc-mit-iptables-string-recent-smtp/ https://sys4.de/de/blog/2014/03/27/fighting-smtp-auth-brute-force-attacks/ to pop3(s)/imap(s) and your needs Best Regards MfG Robert Schetterer -- [*] sys4 AG http://sys4.de, +49 (89) 30 90 46 64 Schleißheimer Straße 26/MG, 80333 München Sitz der Gesellschaft: München, Amtsgericht München: HRB 199263 Vorstand: Patrick Ben Koetter, Marc Schiffbauer Aufsichtsratsvorsitzender: Florian Kirstein
