1

Fail2Ban works fine with the built-in jails, but my custom OpenVPN jail doesn't ban anything, neither does my NGINX-DoS jail. The output of sudo fail2ban-client status openvpn is:

Status for the jail: openvpn
|- Filter
|  |- Currently failed: 0
|  |- Total failed: 0
|  `- File list:    /var/log/openvpn.log
- Actions
|- Currently banned:    2
|- Total banned:    2
`- Banned IP list:  1.2.3.4 1.3.4.5

I changed the IP addresses, BTW. So the jail is working, but the output of iptables-save | grep 1.2.3.4 returns nothing, so the IP is not being blocked. All other jails work fine.

My openvpn.conf file in filter.d is:

# Fail2Ban filter for selected OpenVPN rejections
#
#
[INCLUDES]

before = common.conf

[Definition]

failregex = ^ TLS Error: incoming packet authentication failed from \
[AF_INET\]<HOST>:\d+$
        ^ <HOST>:\d+ Connection reset, restarting
        ^ <HOST>:\d+ TLS Auth Error
        ^ <HOST>:\d+ TLS Error: TLS handshake failed$
        ^ <HOST>:\d+ VERIFY ERROR

ignoreregex = 

and the section in jail.local is:

[openvpn]
enabled  = true
port     = 1194
protocol = tcp
backend = auto
filter   = openvpn
logpath  = /var/log/openvpn.log
action = sendmail[name=openvpn, dest=my_email@my_domain.com]
banaction = iptables-multiport

The same thing is happening with my NGINX jail, fail2ban-client says its banned, and I get an email saying an IP was banned, but nothing happens.

9
  • i use iptables -S | grep fail2ban to get the banned ips. I think it's more appropiate than iptables-save which has a specific saving purpose.
    – bistoco
    Jan 4 '18 at 0:31
  • Still no output though Jan 4 '18 at 0:32
  • The problem is not recording them, it does that just fine. The problem is that they don't get banned. Jan 4 '18 at 0:58
  • Yes, but not the IPs that are supposed to be banned by the OpenVPN jail. The only problem is that jail, other jails ban IPs just fine Jan 4 '18 at 0:59
  • 1
    I set my OpenVPN server to 1194 TCP so it can work behind a port multiplexer Aug 22 '18 at 18:03
1

According to the fail2ban Wiki you might want to try setting protocol = udp instead of protocol = tcp. www.fail2ban.org Wiki

Your banaction 'iptables-multiport' will create a new iptables chain with all banned ips and add this chain to iptables INPUT chain. You can check if this chain is being created correctly with iptables -vnL. Look for a 'f2b-openvpn' chain at the 'Chain INPUT' section at the top of that output and then a 'CHAIN f2b-openvpn' section with all the banned IPs further down that output.

Also consider obfuscating your mail address from you config example.

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