I am trying to :

 set limit frags 10000

and get following info:

 pfctl: cannot set 'frags' limit

When i am trying to set it on 5000 everything works fine.

  • Which version of OpenBSD are you running? What is the output of the command sysctl kern.maxclusters?
    – Flup
    Feb 19, 2015 at 8:09
  • The output is 6144 :D Thanks a lot - i have increased it and everything works fine.
    – Kriss
    Feb 19, 2015 at 8:24

1 Answer 1


From the OpenBSD 5.3 upgrade guide:

pfctl(8) will abort and fail to load the rule set if the 'frags' limit in pf.conf is higher than the kern.maxclusters sysctl This is to guard against allowing a system to run out of mbuf clusters. If it is not set, the new default is 25% of kern.maxclusters.

If you increase kern.maxclusters, you will also raise the limit in pf for frags.

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