document logging through bpf

This commit is contained in:
Luigi Rizzo 2010-10-13 22:07:57 +00:00
parent 7e05daae8f
commit 81ab11744e
Notes: svn2git 2020-12-20 02:59:44 +00:00
svn path=/head/; revision=213810

View File

@ -557,28 +557,33 @@ packet delivery.
Note: this condition is checked before any other condition, including
ones such as keep-state or check-state which might have side effects.
.It Cm log Op Cm logamount Ar number
When a packet matches a rule with the
Packets matching a rule with the
.Cm log
keyword, a message will be
logged to
keyword will be made available for logging in two ways:
if the sysctl variable
.Va net.inet.ip.fw.verbose
is set to 0 (default), one can use
.Xr bpf 4
attached to the
.Xr ipfw0
pseudo interface. There is no overhead if no
.Xr bpf
is attached to the pseudo interface.
.Pp
If
.Va net.inet.ip.fw.verbose
is set to 1, packets will be logged to
.Xr syslogd 8
with a
.Dv LOG_SECURITY
facility.
The logging only occurs if the sysctl variable
.Va net.inet.ip.fw.verbose
is set to 1
(which is the default when the kernel is compiled with
.Dv IPFIREWALL_VERBOSE )
and the number of packets logged so far for that
particular rule does not exceed the
facility up to a maximum of
.Cm logamount
parameter.
packets.
If no
.Cm logamount
is specified, the limit is taken from the sysctl variable
.Va net.inet.ip.fw.verbose_limit .
In both cases, a value of 0 removes the logging limit.
In both cases, a value of 0 means unlimited logging.
.Pp
Once the limit is reached, logging can be re-enabled by
clearing the logging counter or the packet counter for that entry, see the