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3.4 OS Configuration

This section contains information on critical OS tuning items. More detailed tuning information can be found in the section on Performance Tuning.

FreeBSD Configuration

The standard FreeBSD kernel imposes a per-process limit of 512 MB of memory. This is not enough for most Bro installations.

To check your current limit type:

     limits -H

Unfortunately the only way to increase this limit in FreeBSD 4.x is to reconfigure and rebuild the kernel. In FreeBSD 5.x it is much easier. Just increase kern.maxdsiz in /boot/defaults/loader.conf and reboot. For example:

     kern.maxdsiz="2G"

and look at the datasize setting, which should be the same as your amount of RAM. If this is not true, see section Hardware and OS Tuning for information on fixing this.

For FreeBSD 5.3+, BPF devices are no longer created using MAKEDEV, but rather are created on demand. This is configured automatically by running 'make install-brolite', or you can figure it by hand by adding the following to /etc/rc.local

devfs ruleset 15
devfs rule add 15 path 'bpf*' mode 660 user bro

Linux Configuration

You may want increase these for a high traffic environment.

not done: need to get recommended values for these:

/proc/sys/net/core/rmem_default (IP-Stack socket receive queue)
/proc/sys/net/core/rmem_max     (similar to rmem_default)
/proc/sys/net/core/netdev_max_backlog (queue between driver and socket)