一直以來都找不到fail2ban 去阻擋SASL認證失敗的語法，網路上之前看到的都是這幾篇
http://blog.xuite.net/pippeng/blog/63675336-Fail2Ban+for+Dovecot%3E
http://wiki.dovecot.org/HowTo/Fail2Ban
今天驚覺其實是我想錯了，這個應該不關dovecot的事！
應該是要找SASL認證錯誤的語法才對
不過dovecot預設的好像也有問題
所以我找到了這篇
http://www.howtoforge.com/forums/showthread.php?t=51349
發現了這個語法
failregex = (?i): warning: [-._\w]+[<HOST>]: SASL (?:LOGIN|PLAIN|(?:CRAM|DIGEST)-MD5) authentication failed: \w
然後測試了一下
Running tests=============
Use regex file : /etc/fail2ban/filter.d/dovecot-pop3imap.conf
Use log file : /var/log/maillog
Results
=======
Failregex
|- Regular expressions:
| [1] (?i): warning: [-._\w]+[<HOST>]: SASL (?:LOGIN|PLAIN|(?:CRAM|DIGEST)-MD5) authentication failed: \w
|
`- Number of matches:
[1] 450 match(es)
Ignoreregex
|- Regular expressions:
|
`- Number of matches:
Summary
=======
Addresses found:
[1]
199.36.73.98 (Wed Oct 16 01:30:56 2013)
中間省略數百筆
223.198.165.194 (Wed Oct 16 01:47:37 2013)
再次省略數百筆
113.59.11.87 (Wed Oct 16 03:47:28 2013)
省略數百筆
114.250.15.84 (Wed Oct 16 10:51:30 2013)
省略數百筆
接下來就放著讓fail2ban 去跑跑看囉！