:tocdepth: 3

base/protocols/conn/main.zeek
=============================
.. zeek:namespace:: Conn

This script manages the tracking/logging of general information regarding
TCP, UDP, and ICMP traffic.  For UDP and ICMP, "connections" are to
be interpreted using flow semantics (sequence of packets from a source
host/port to a destination host/port).  Further, ICMP "ports" are to
be interpreted as the source port meaning the ICMP message type and
the destination port being the ICMP message code.

:Namespace: Conn
:Imports: :doc:`base/utils/site.zeek </scripts/base/utils/site.zeek>`

Summary
~~~~~~~
Types
#####
============================================ ===================================================================
:zeek:type:`Conn::Info`: :zeek:type:`record` The record type which contains column fields of the connection log.
============================================ ===================================================================

Redefinitions
#############
============================================ ======================================================
:zeek:type:`Log::ID`: :zeek:type:`enum`      The connection logging stream identifier.
                                             
                                             * :zeek:enum:`Conn::LOG`
:zeek:type:`connection`: :zeek:type:`record` 
                                             
                                             :New Fields: :zeek:type:`connection`
                                             
                                               conn: :zeek:type:`Conn::Info` :zeek:attr:`&optional`
============================================ ======================================================

Events
######
============================================= ===============================================================
:zeek:id:`Conn::log_conn`: :zeek:type:`event` Event that can be handled to access the :zeek:type:`Conn::Info`
                                              record as it is sent on to the logging framework.
============================================= ===============================================================

Hooks
#####
========================================================= =============================================
:zeek:id:`Conn::log_policy`: :zeek:type:`Log::PolicyHook` A default logging policy hook for the stream.
========================================================= =============================================


Detailed Interface
~~~~~~~~~~~~~~~~~~
Types
#####
.. zeek:type:: Conn::Info
   :source-code: base/protocols/conn/main.zeek 20 151

   :Type: :zeek:type:`record`

      ts: :zeek:type:`time` :zeek:attr:`&log`
         This is the time of the first packet.

      uid: :zeek:type:`string` :zeek:attr:`&log`
         A unique identifier of the connection.

      id: :zeek:type:`conn_id` :zeek:attr:`&log`
         The connection's 4-tuple of endpoint addresses/ports.

      proto: :zeek:type:`transport_proto` :zeek:attr:`&log`
         The transport layer protocol of the connection.

      service: :zeek:type:`string` :zeek:attr:`&log` :zeek:attr:`&optional`
         An identification of an application protocol being sent over
         the connection.

      duration: :zeek:type:`interval` :zeek:attr:`&log` :zeek:attr:`&optional`
         How long the connection lasted.  For 3-way or 4-way connection
         tear-downs, this will not include the final ACK.

      orig_bytes: :zeek:type:`count` :zeek:attr:`&log` :zeek:attr:`&optional`
         The number of payload bytes the originator sent. For TCP
         this is taken from sequence numbers and might be inaccurate
         (e.g., due to large connections).

      resp_bytes: :zeek:type:`count` :zeek:attr:`&log` :zeek:attr:`&optional`
         The number of payload bytes the responder sent. See
         *orig_bytes*.

      conn_state: :zeek:type:`string` :zeek:attr:`&log` :zeek:attr:`&optional`
         Possible *conn_state* values:
         
         * S0: Connection attempt seen, no reply.
         
         * S1: Connection established, not terminated.
         
         * SF: Normal establishment and termination.
           Note that this is the same symbol as for state S1.
           You can tell the two apart because for S1 there will not be any
           byte counts in the summary, while for SF there will be.
         
         * REJ: Connection attempt rejected.
         
         * S2: Connection established and close attempt by originator seen
           (but no reply from responder).
         
         * S3: Connection established and close attempt by responder seen
           (but no reply from originator).
         
         * RSTO: Connection established, originator aborted (sent a RST).
         
         * RSTR: Responder sent a RST.
         
         * RSTOS0: Originator sent a SYN followed by a RST, we never saw a
           SYN-ACK from the responder.
         
         * RSTRH: Responder sent a SYN ACK followed by a RST, we never saw a
           SYN from the (purported) originator.
         
         * SH: Originator sent a SYN followed by a FIN, we never saw a
           SYN ACK from the responder (hence the connection was "half" open).
         
         * SHR: Responder sent a SYN ACK followed by a FIN, we never saw a
           SYN from the originator.
         
         * OTH: No SYN seen, just midstream traffic (one example of this
           is a "partial connection" that was not later closed).

      local_orig: :zeek:type:`bool` :zeek:attr:`&log` :zeek:attr:`&optional`
         If the connection is originated locally, this value will be T.
         If it was originated remotely it will be F.  In the case that
         the :zeek:id:`Site::local_nets` variable is undefined, this
         field will be left empty at all times.

      local_resp: :zeek:type:`bool` :zeek:attr:`&log` :zeek:attr:`&optional`
         If the connection is responded to locally, this value will be T.
         If it was responded to remotely it will be F.  In the case that
         the :zeek:id:`Site::local_nets` variable is undefined, this
         field will be left empty at all times.

      missed_bytes: :zeek:type:`count` :zeek:attr:`&log` :zeek:attr:`&default` = ``0`` :zeek:attr:`&optional`
         Indicates the number of bytes missed in content gaps, which
         is representative of packet loss.  A value other than zero
         will normally cause protocol analysis to fail but some
         analysis may have been completed prior to the packet loss.

      history: :zeek:type:`string` :zeek:attr:`&log` :zeek:attr:`&optional`
         Records the state history of connections as a string of
         letters.  The meaning of those letters is:
         
         ======  ====================================================
         Letter  Meaning
         ======  ====================================================
         s       a SYN w/o the ACK bit set
         h       a SYN+ACK ("handshake")
         a       a pure ACK
         d       packet with payload ("data")
         f       packet with FIN bit set
         r       packet with RST bit set
         c       packet with a bad checksum (applies to UDP too)
         g       a content gap
         t       packet with retransmitted payload
         w       packet with a zero window advertisement
         i       inconsistent packet (e.g. FIN+RST bits set)
         q       multi-flag packet (SYN+FIN or SYN+RST bits set)
         ^       connection direction was flipped by Zeek's heuristic
         ======  ====================================================
         
         If the event comes from the originator, the letter is in
         upper-case; if it comes from the responder, it's in
         lower-case.  The 'a', 'd', 'i' and 'q' flags are
         recorded a maximum of one time in either direction regardless
         of how many are actually seen.  'f', 'h', 'r' and
         's' can be recorded multiple times for either direction
         if the associated sequence number differs from the
         last-seen packet of the same flag type.
         'c', 'g', 't' and 'w' are recorded in a logarithmic fashion:
         the second instance represents that the event was seen
         (at least) 10 times; the third instance, 100 times; etc.

      orig_pkts: :zeek:type:`count` :zeek:attr:`&log` :zeek:attr:`&optional`
         Number of packets that the originator sent.
         Only set if :zeek:id:`use_conn_size_analyzer` = T.

      orig_ip_bytes: :zeek:type:`count` :zeek:attr:`&log` :zeek:attr:`&optional`
         Number of IP level bytes that the originator sent (as seen on
         the wire, taken from the IP total_length header field).
         Only set if :zeek:id:`use_conn_size_analyzer` = T.

      resp_pkts: :zeek:type:`count` :zeek:attr:`&log` :zeek:attr:`&optional`
         Number of packets that the responder sent.
         Only set if :zeek:id:`use_conn_size_analyzer` = T.

      resp_ip_bytes: :zeek:type:`count` :zeek:attr:`&log` :zeek:attr:`&optional`
         Number of IP level bytes that the responder sent (as seen on
         the wire, taken from the IP total_length header field).
         Only set if :zeek:id:`use_conn_size_analyzer` = T.

      tunnel_parents: :zeek:type:`set` [:zeek:type:`string`] :zeek:attr:`&log` :zeek:attr:`&optional`
         If this connection was over a tunnel, indicate the
         *uid* values for any encapsulating parent connections
         used over the lifetime of this inner connection.

      orig_l2_addr: :zeek:type:`string` :zeek:attr:`&log` :zeek:attr:`&optional`
         (present if :doc:`/scripts/policy/protocols/conn/mac-logging.zeek` is loaded)

         Link-layer address of the originator, if available.

      resp_l2_addr: :zeek:type:`string` :zeek:attr:`&log` :zeek:attr:`&optional`
         (present if :doc:`/scripts/policy/protocols/conn/mac-logging.zeek` is loaded)

         Link-layer address of the responder, if available.

      vlan: :zeek:type:`int` :zeek:attr:`&log` :zeek:attr:`&optional`
         (present if :doc:`/scripts/policy/protocols/conn/vlan-logging.zeek` is loaded)

         The outer VLAN for this connection, if applicable.

      inner_vlan: :zeek:type:`int` :zeek:attr:`&log` :zeek:attr:`&optional`
         (present if :doc:`/scripts/policy/protocols/conn/vlan-logging.zeek` is loaded)

         The inner VLAN for this connection, if applicable.

      speculative_service: :zeek:type:`string` :zeek:attr:`&log` :zeek:attr:`&optional`
         (present if :doc:`/scripts/policy/protocols/conn/speculative-service.zeek` is loaded)

         Protocol that was determined by a matching signature after the beginning
         of a connection. In this situation no analyzer can be attached and hence
         the data cannot be analyzed nor the protocol can be confirmed.

   The record type which contains column fields of the connection log.

Events
######
.. zeek:id:: Conn::log_conn
   :source-code: base/protocols/conn/main.zeek 155 155

   :Type: :zeek:type:`event` (rec: :zeek:type:`Conn::Info`)

   Event that can be handled to access the :zeek:type:`Conn::Info`
   record as it is sent on to the logging framework.

Hooks
#####
.. zeek:id:: Conn::log_policy
   :source-code: base/protocols/conn/main.zeek 17 17

   :Type: :zeek:type:`Log::PolicyHook`

   A default logging policy hook for the stream.


