IPL(4)IPL(4)NAMEipl - IP packet log device
DESCRIPTION
The ipl pseudo device's purpose is to provide an easy way to gather
packet headers of packets you wish to log. If a packet header is to be
logged, the entire header is logged (including any IP options - TCP/UDP
options are not included when it calculates header size) or not at all.
The packet contents is also logged after the header.
Prepending every packet header logged is a structure containing infor‐
mation relevant to the packet following and why it was logged. The
structure's format is as follows:
struct ipl_ci {
u_long sec; /* time when the packet was logged */
u_long usec;
u_long plen; /* length of packet data logged */
u_short hlen; /* length of headers logged */
u_short rule; /* rule number (for log ...) or 0 if result = log */
u_long flags:24; /* XXX FIXME do we care about the extra bytes? */
#if (defined(OpenBSD) && (OpenBSD <= 1991011) && (OpenBSD >= 199606))
u_long filler:8; /* XXX FIXME do we care? */
u_char ifname[IFNAMSIZ];
#else
u_long unit:8;
u_char ifname[4];
#endif
};
In the case of the header causing the buffer to finish on a non-32bit
boundary, padding will be `appended' to ensure that the next log entry
is aligned to a 32bit boundary.
If the packet contents is more then 128 bytes, then only 128 bytes of the
packet contents is logged. Should the packet contents finish on a non-32bit
boundary, then the last few bytes are not logged to ensure the log entry
is aligned to a 32bit boundary.
ipl is a read-only (sequential) character pseudo-device.
The ioctls which are loaded with this device can be found under ipf(4).
The only ioctl which is used for logging and doesn't affect the filter is:
ioctl(fd, SIOCIPFFB, int *)
This ioctl flushes the log buffer and returns the number of bytes
flushed.
There is currently no support for non-blocking IO with this device,
meaning all read operations should be considered blocking in nature (if
there is no data to read, it will sleep until some is made available).
SEE ALSOipf(4)BUGS
Packet headers are dropped when the internal buffer (static size)
fills.
FILES
/dev/ipl0
IPL(4)
