Add documentation (#110)

docs/administration/fail2ban-setup.md

@@ -0,0 +1,29 @@
+# Fail2ban setup
+
+Fail2ban can be used to ban IPs that try to bruteforce the login page.
+Log level must be set at least to `warn`.
+
+Add this filter in `etc/fail2ban/filter.d/opengist.conf` :
+```ini
+[Definition]
+failregex =  Invalid .* authentication attempt from <HOST>
+ignoreregex =
+```
+
+Add this jail in `etc/fail2ban/jail.d/opengist.conf` :
+```ini
+[opengist]
+enabled = true
+filter = opengist
+logpath = /home/*/.opengist/log/opengist.log
+maxretry = 10
+findtime = 3600
+bantime = 600
+banaction = iptables-allports
+port = anyport
+```
+
+Then run
+```shell
+service fail2ban restart
+```