FreeBSD 7.0 manual page repository

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pflogd - packet filter logging daemon



      pflogd - packet filter logging daemon


      pflogd [-Dx] [-d delay] [-f filename] [-i interface] [-s snaplen]


      pflogd is a background daemon which reads packets logged by pf(4) to a
      pflog(4) interface, normally pflog0, and writes the packets to a logfile
      (normally /var/log/pflog) in tcpdump(1) binary format.  These logs can be
      reviewed later using the -r option of tcpdump(1), hopefully offline in
      case there are bugs in the packet parsing code of tcpdump(1).
      pflogd closes and then re-opens the log file when it receives SIGHUP,
      permitting newsyslog(8) to rotate logfiles automatically.  SIGALRM causes
      pflogd to flush the current logfile buffers to the disk, thus making the
      most recent logs available.  The buffers are also flushed every delay
      If the log file contains data after a restart or a SIGHUP, new logs are
      appended to the existing file.  If the existing log file was created with
      a different snaplen, pflogd temporarily uses the old snaplen to keep the
      log file consistent.
      pflogd tries to preserve the integrity of the log file against I/O
      errors.  Furthermore, integrity of an existing log file is verified
      before appending.  If there is an invalid log file or an I/O error, the
      log file is moved out of the way and a new one is created.  If a new file
      cannot be created, logging is suspended until a SIGHUP or a SIGALRM is
      The options are as follows:
      -D      Debugging mode.  pflogd does not disassociate from the control‐
              ling terminal.
      -d delay
              Time in seconds to delay between automatic flushes of the file.
              This may be specified with a value between 5 and 3600 seconds.
              If not specified, the default is 60 seconds.
      -f filename
              Log output filename.  Default is /var/log/pflog.
      -i interface
              Specifies the pflog(4) interface to use.  By default, pflogd will
              use pflog0.
      -s snaplen
              Analyze at most the first snaplen bytes of data from each packet
              rather than the default of 116.  The default of 116 is adequate
              for IP, ICMP, TCP, and UDP headers but may truncate protocol
              information for other protocols.  Other file parsers may desire a
              higher snaplen.
      -x      Check the integrity of an existing log file, and return.
              Selects which packets will be dumped, using the regular language
              of tcpdump(1).


      /var/run/  Process ID of the currently running pflogd.
      /var/log/pflog       Default log file.


      Log specific tcp packets to a different log file with a large snaplen
      (useful with a log-all rule to dump complete sessions):
            # pflogd -s 1600 -f suspicious.log port 80 and host evilhost
      Log from another pflog(4) interface, excluding specific packets:
            # pflogd -i pflog3 -f network3.log "not (tcp and port 23)"
      Display binary logs:
            # tcpdump -n -e -ttt -r /var/log/pflog
      Display the logs in real time (this does not interfere with the operation
      of pflogd):
            # tcpdump -n -e -ttt -i pflog0
      Tcpdump has been extended to be able to filter on the pfloghdr structure
      defined in 〈net/if_pflog.h〉.  Tcpdump can restrict the output to packets
      logged on a specified interface, a rule number, a reason, a direction, an
      IP family or an action.
      ip               Address family equals IPv4.
      ip6              Address family equals IPv6.
      ifname kue0      Interface name equals "kue0".
      on kue0          Interface name equals "kue0".
      ruleset authpf   Ruleset name equals "authpf".
      rulenum 10       Rule number equals 10.
      reason match     Reason equals match.  Also accepts "bad-offset", "frag‐
                       ment", "bad-timestamp", "short", "normalize", "memory",
                       "congestion", "ip-option", "proto-cksum", "state-mis‐
                       match", "state-insert", "state-limit", "src-limit", and
      action pass      Action equals pass.  Also accepts "block".
      inbound          The direction was inbound.
      outbound         The direction was outbound.
      Display the logs in real time of inbound packets that were blocked on the
      wi0 interface:
            # tcpdump -n -e -ttt -i pflog0 inbound and action block and on wi0
      tcpdump(1), pcap(3), pf(4), pflog(4), pf.conf(5), newsyslog(8)


      The pflogd command appeared in OpenBSD 3.0.


      pflogd was written by Can Erkin Acar 〈〉.


Based on BSD UNIX
FreeBSD is an advanced operating system for x86 compatible (including Pentium and Athlon), amd64 compatible (including Opteron, Athlon64, and EM64T), UltraSPARC, IA-64, PC-98 and ARM architectures. It is derived from BSD, the version of UNIX developed at the University of California, Berkeley. It is developed and maintained by a large team of individuals. Additional platforms are in various stages of development.