Semi-OT: Fail2ban Issue

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On a CentOS 6.7 system that’s been running fail2ban for a long time, we recently started seeing this:
ct 28 19:00:59 fail2ban.action[17561]: ERROR iptables -w -D
INPUT -p tcp –dport SSH -j f2b-SSH#012iptables -w -F f2b-SSH#012iptables
-w -X f2b-SSH — stderr: “iptables v1.4.7: option `-w’ requires an argument\nTry `iptables -h’ or ‘iptables –help’ for more information.\niptables v1.4.7: option `-w’ requires an argument\nTry
`iptables -h’ or ‘iptables –help’ for more information.\niptables v1.4.7:
option `-w’ requires an argument\nTry `iptables -h’ or ‘iptables –help’
for more information.\n”

My manager thinks it might have been due to the recent update. I, however, am extremely confused, as in neither in the manpage, nore fail2ban –help, do I find *ANY* reference to a -w flag.

Anyone have a clue here?

mark

3 thoughts on - Semi-OT: Fail2ban Issue

  • This should probably be a bug report for the fail2ban EPEL maintainer, the problem was introduced in version 0.9.3

    From the file /etc/fail2ban/action.d/iptables-common.conf

    # Option: lockingopt
    # Notes.: Option was introduced to iptables to prevent multiple instances from
    # running concurrently and causing irratic behavior. -w was introduced
    # in iptables 1.4.20, so might be absent on older systems
    # See https://github.com/fail2ban/fail2ban/issues/1122
    # Values: STRING
    lockingopt = -w

    Now, CentOS 6.7 has iptables 1.4.7 and the “wait” option does not seem to have been backported by RedHat, so the EPEL package for EL6 should probably not have this as the default.

    My workaround was to create a file /etc/fail2ban/action.d/iptables-common.local that contains

    [Init]
    lockingopt …

    -Thomas

  • In article <1446132814771.22431@slac.stanford.edu>, Eriksson, Thomas wrote:

    Looks like it has been fixed in the update fail2ban-0.9.3-1.el6.1

    Cheers Tony

  • Tony Mountifield wrote:
    Thanks to Thomas, and I created the .local file. Thanks to Tony, and I
    just updated fail2ban, checked iptables-common.conf, and then rm’d the
    .local file.

    mark