ip_contrack

[Patrick Schaaf]

> echo "whatever" > /proc/sys/net/ipv4/ip_conntrack
> 
> Remember that increasing /proc/sys/net/ipv4/ip_conntrack uses more memory.

Note: the memory is not consumed immediately; the setting provides an
upper bound on how much (nonpageable kernel) memory _may_ be consumed
by conntrack.

> According to the FAQ about 500 bytes per tracked connection.

To be exact: r!grep conntrack /proc/slabinfo
ip_conntrack          11     22    352    2    2    1

The first number is the number of conntrack items allocated right now.
The second number is the "slab cache" total of items allocated (may
be shrunk when memory is tight). The third value is the size of
the individual item. Unless there is additional allocation per conntrack,
the FAQ seems to guess a bit higher than reality :)

regards
  Patrick