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PF: Runtime Options

Options are used to control PF's operation. Options are specified in pf.conf using the set directive.

set block-policy

Sets the default behavior for filter rules that specify the block action.

• drop - packet is silently dropped.
• return - a TCP RST packet is returned for blocked TCP packets and an ICMP Unreachable packet is returned for all others.

Note that individual filter rules can override the default response.

set limit

frags - maximum number of entries in the memory pool used for packet reassembly (scrub rules). Default is 5000.

states - maximum number of entries in the memory pool used for state table entries (filter rules that specify keep state). Default is 10000.

set loginterface int

Sets the interface for which PF should gather statistics such as bytes in/out and packets passed/blocked. Statistics can only be gathered for one interface at a time. Note that the match, bad-offset, etc., counters and the state table counters are recorded regardless of whether loginterface is set or not.

set optimization

Optimize PF for one of the following network environments:

• normal - suitable for almost all networks. This is the default.
• high-latency - high latency networks such as satellite connections.
• aggressive - aggressively expires connections from the state table. This can greatly reduce the memory requirements on a busy firewall at the risk of dropping idle connections early.
• conservative - extremely conservative settings. This avoids dropping idle connections at the expense of greater memory utilization and slightly increased processor utilization.

set timeout

interval - seconds between purges of expired states and packet fragments.

frag - seconds before an unassembled fragment is expired.

Example:

set timeout interval 10 set timeout frag 30 set limit { frags 5000, states 2500 } set optimization high-latency set block-policy return set loginterface dc0

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