IPL(7)IPL(7)NAME
ipl - 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 are also logged after the header. If the log
reader is busy or otherwise unable to read log records, upto IPLLOGSIZE
(8192 is the default) bytes of data are stored.
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:
/*
* Log structure. Each packet header logged is prepended by one of
* these. Following this in the log records read from the device
* will be an ipflog structure which is then followed by any packet
* data.
*/
typedef struct iplog {
u_32_t ipl_magic;
u_int ipl_count;
u_32_t ipl_sec;
u_long ipl_usec;
size_t ipl_dsize;
struct iplog *ipl_next;
} iplog_t;
typedef struct ipflog {
u_int fl_unit;
char fl_ifname[IFNAMSIZ];
u_short fl_plen; /* extra data after hlen */
u_char fl_hlen; /* length of IP headers saved */
u_short fl_loglevel; /* syslog log level */
u_32_t fl_rule;
u_32_t fl_group;
u_32_t fl_flags;
u_32_t fl_lflags;
u_32_t limit_type; /* Limit type */
u_32_t limit_threshold;/* Configured limit */
u_32_t limit_current; /* current # of connections */
u_32_t limit_excd; /* # of times limit exceeded so far */
u_32_t limit_lfreq; /* log per blocked connections */
} ipflog_t;
When reading from the ipl device, it is necessary to call read(2) with
a buffer big enough to hold at least 1 complete log record - reading of
partial log records is not supported.
If the packet contents is more then 128 bytes when log body is used,
then only 128 bytes of the packet contents is logged.
Although it is only possible to read from the ipl device, opening it
for writing is required when using an ioctl which changes any kernel
data.
The ioctls which are loaded with this device can be found under ipf(4).
The ioctls which are for use with logging and don't affect the filter
are:
ioctl(fd, SIOCIPFFB, int *)
ioctl(fd, FIONREAD, int *)
The SIOCIPFFB ioctl flushes the log buffer and returns the number of
bytes flushed. FIONREAD returns the number of bytes currently used for
storing log data. If IPFILTER_LOG is not defined when compiling, SIO‐
CIPFFB is not available and FIONREAD will return but not do anything.
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)NOTES
Packet headers are dropped when the internal buffer (static size)
fills.
FILES
/dev/ipl
AUTHOR
IPFilter was originally developed by Darren Reed. This HP-UX
enhanced version of IPFilter is based on the open source version
3.5 Alpha 5.
IPL(7)
