base/bif/plugins/Zeek_TCP.events.bif.zeek
- GLOBAL
- Namespace
GLOBAL
Summary
Events
Generated at the end of reassembled TCP connections. |
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Generated for a SYN packet. |
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Generated for an unsuccessful connection attempt. |
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Generated when seeing a SYN-ACK packet from the responder in a TCP handshake. |
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Generated for a TCP connection that finished normally. |
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Generated for the first ACK packet seen for a TCP connection from its originator. |
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Generated when one endpoint of a TCP connection attempted to gracefully close the connection, but the other endpoint is in the TCP_INACTIVE state. |
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Generated when a previously inactive endpoint attempts to close a TCP connection via a normal FIN handshake or an abort RST sequence. |
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Generated for each still-open TCP connection when Zeek terminates. |
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Generated for a rejected TCP connection. |
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Generated when an endpoint aborted a TCP connection. |
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Generated when failing to write contents of a TCP stream to a file. |
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Generated when reassembly starts for a TCP connection. |
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Generated for a new active TCP connection if Zeek did not see the initial handshake. |
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Generated for each chunk of reassembled TCP payload. |
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Generated if a TCP flow crosses a checksum-error threshold, per ‘C’/’c’ history reporting. |
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Generated if a TCP flow crosses a gap threshold, per ‘G’/’g’ history reporting. |
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Generated if a TCP flow crosses a retransmission threshold, per ‘T’/’t’ history reporting. |
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Generated if a TCP flow crosses a zero-window threshold, per ‘W’/’w’ history reporting. |
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Generated for each option found in a TCP header. |
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Generated for each TCP header that contains TCP options. |
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Generated for every TCP packet. |
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Generated for each detected TCP segment retransmission. |
Detailed Interface
Events
- connection_EOF
- Type
event
(c:connection
, is_orig:bool
)
Generated at the end of reassembled TCP connections. The TCP reassembler raised the event once for each endpoint of a connection when it finished reassembling the corresponding side of the communication.
- Parameters
c – The connection.
is_orig – True if the event is raised for the originator side.
See also:
connection_SYN_packet
,connection_attempt
,connection_established
,connection_finished
,connection_first_ACK
,connection_half_finished
,connection_partial_close
,connection_pending
,connection_rejected
,connection_reset
,connection_reused
,connection_state_remove
,connection_status_update
,connection_timeout
,scheduled_analyzer_applied
,new_connection
,new_connection_contents
,partial_connection
- connection_SYN_packet
- Type
event
(c:connection
, pkt:SYN_packet
)
Generated for a SYN packet. Zeek raises this event for every SYN packet seen by its TCP analyzer.
- Parameters
c – The connection.
pkt – Information extracted from the SYN packet.
See also:
connection_EOF
,connection_attempt
,connection_established
,connection_finished
,connection_first_ACK
,connection_half_finished
,connection_partial_close
,connection_pending
,connection_rejected
,connection_reset
,connection_reused
,connection_state_remove
,connection_status_update
,connection_timeout
,scheduled_analyzer_applied
,new_connection
,new_connection_contents
,partial_connection
Note
This event has quite low-level semantics and can potentially be expensive to generate. It should only be used if one really needs the specific information passed into the handler via the
pkt
argument. If not, handling one of the otherconnection_*
events is typically the better approach.
- connection_attempt
- Type
event
(c:connection
)
Generated for an unsuccessful connection attempt. This event is raised when an originator unsuccessfully attempted to establish a connection. “Unsuccessful” is defined as at least
tcp_attempt_delay
seconds having elapsed since the originator first sent a connection establishment packet to the destination without seeing a reply.- Parameters
c – The connection.
See also:
connection_EOF
,connection_SYN_packet
,connection_established
,connection_finished
,connection_first_ACK
,connection_half_finished
,connection_partial_close
,connection_pending
,connection_rejected
,connection_reset
,connection_reused
,connection_state_remove
,connection_status_update
,connection_timeout
,scheduled_analyzer_applied
,new_connection
,new_connection_contents
,partial_connection
- connection_established
- Type
event
(c:connection
)
Generated when seeing a SYN-ACK packet from the responder in a TCP handshake. An associated SYN packet was not seen from the originator side if its state is not set to
TCP_ESTABLISHED
. The final ACK of the handshake in response to SYN-ACK may or may not occur later, one way to tell is to check the history field ofconnection
to see if the originator sent an ACK, indicated by ‘A’ in the history string.- Parameters
c – The connection.
See also:
connection_EOF
,connection_SYN_packet
,connection_attempt
,connection_finished
,connection_first_ACK
,connection_half_finished
,connection_partial_close
,connection_pending
,connection_rejected
,connection_reset
,connection_reused
,connection_state_remove
,connection_status_update
,connection_timeout
,scheduled_analyzer_applied
,new_connection
,new_connection_contents
,partial_connection
- connection_finished
- Type
event
(c:connection
)
Generated for a TCP connection that finished normally. The event is raised when a regular FIN handshake from both endpoints was observed.
- Parameters
c – The connection.
See also:
connection_EOF
,connection_SYN_packet
,connection_attempt
,connection_established
,connection_first_ACK
,connection_half_finished
,connection_partial_close
,connection_pending
,connection_rejected
,connection_reset
,connection_reused
,connection_state_remove
,connection_status_update
,connection_timeout
,scheduled_analyzer_applied
,new_connection
,new_connection_contents
,partial_connection
- connection_first_ACK
- Type
event
(c:connection
)
Generated for the first ACK packet seen for a TCP connection from its originator.
- Parameters
c – The connection.
See also:
connection_EOF
,connection_SYN_packet
,connection_attempt
,connection_established
,connection_finished
,connection_half_finished
,connection_partial_close
,connection_pending
,connection_rejected
,connection_reset
,connection_reused
,connection_state_remove
,connection_status_update
,connection_timeout
,scheduled_analyzer_applied
,new_connection
,new_connection_contents
,partial_connection
Note
This event has quite low-level semantics and should be used only rarely.
- connection_half_finished
- Type
event
(c:connection
)
Generated when one endpoint of a TCP connection attempted to gracefully close the connection, but the other endpoint is in the TCP_INACTIVE state. This can happen due to split routing, in which Zeek only sees one side of a connection.
- Parameters
c – The connection.
See also:
connection_EOF
,connection_SYN_packet
,connection_attempt
,connection_established
,connection_finished
,connection_first_ACK
,connection_partial_close
,connection_pending
,connection_rejected
,connection_reset
,connection_reused
,connection_state_remove
,connection_status_update
,connection_timeout
,scheduled_analyzer_applied
,new_connection
,new_connection_contents
,partial_connection
- connection_partial_close
- Type
event
(c:connection
)
Generated when a previously inactive endpoint attempts to close a TCP connection via a normal FIN handshake or an abort RST sequence. When the endpoint sent one of these packets, Zeek waits
tcp_partial_close_delay
prior to generating the event, to give the other endpoint a chance to close the connection normally.- Parameters
c – The connection.
See also:
connection_EOF
,connection_SYN_packet
,connection_attempt
,connection_established
,connection_finished
,connection_first_ACK
,connection_half_finished
,connection_pending
,connection_rejected
,connection_reset
,connection_reused
,connection_state_remove
,connection_status_update
,connection_timeout
,scheduled_analyzer_applied
,new_connection
,new_connection_contents
,partial_connection
- connection_pending
- Type
event
(c:connection
)
Generated for each still-open TCP connection when Zeek terminates.
- Parameters
c – The connection.
See also:
connection_EOF
,connection_SYN_packet
,connection_attempt
,connection_established
,connection_finished
,connection_first_ACK
,connection_half_finished
,connection_partial_close
,connection_rejected
,connection_reset
,connection_reused
,connection_state_remove
,connection_status_update
,connection_timeout
,scheduled_analyzer_applied
,new_connection
,new_connection_contents
,partial_connection
,zeek_done
- connection_rejected
- Type
event
(c:connection
)
Generated for a rejected TCP connection. This event is raised when an originator attempted to setup a TCP connection but the responder replied with a RST packet denying it.
- Parameters
c – The connection.
See also:
connection_EOF
,connection_SYN_packet
,connection_attempt
,connection_established
,connection_finished
,connection_first_ACK
,connection_half_finished
,connection_partial_close
,connection_pending
,connection_reset
,connection_reused
,connection_state_remove
,connection_status_update
,connection_timeout
,scheduled_analyzer_applied
,new_connection
,new_connection_contents
,partial_connection
Note
If the responder does not respond at all,
connection_attempt
is raised instead. If the responder initially accepts the connection but aborts it later, Zeek first generatesconnection_established
and thenconnection_reset
.
- connection_reset
- Type
event
(c:connection
)
Generated when an endpoint aborted a TCP connection. The event is raised when one endpoint of an established TCP connection aborted by sending a RST packet.
- Parameters
c – The connection.
See also:
connection_EOF
,connection_SYN_packet
,connection_attempt
,connection_established
,connection_finished
,connection_first_ACK
,connection_half_finished
,connection_partial_close
,connection_pending
,connection_rejected
,connection_reused
,connection_state_remove
,connection_status_update
,connection_timeout
,scheduled_analyzer_applied
,new_connection
,new_connection_contents
,partial_connection
- contents_file_write_failure
- Type
event
(c:connection
, is_orig:bool
, msg:string
)
Generated when failing to write contents of a TCP stream to a file.
- Parameters
c – The connection whose contents are being recorded.
is_orig – Which side of the connection encountered a failure to write.
msg – A reason or description for the failure.
See also:
set_contents_file
,get_contents_file
- new_connection_contents
- Type
event
(c:connection
)
Generated when reassembly starts for a TCP connection. This event is raised at the moment when Zeek’s TCP analyzer enables stream reassembly for a connection.
- Parameters
c – The connection.
See also:
connection_EOF
,connection_SYN_packet
,connection_attempt
,connection_established
,connection_finished
,connection_first_ACK
,connection_half_finished
,connection_partial_close
,connection_pending
,connection_rejected
,connection_reset
,connection_reused
,connection_state_remove
,connection_status_update
,connection_timeout
,scheduled_analyzer_applied
,new_connection
,partial_connection
- partial_connection
- Type
event
(c:connection
)
Generated for a new active TCP connection if Zeek did not see the initial handshake. This event is raised when Zeek has observed traffic from each endpoint, but the activity did not begin with the usual connection establishment.
- Parameters
c – The connection.
See also:
connection_EOF
,connection_SYN_packet
,connection_attempt
,connection_established
,connection_finished
,connection_first_ACK
,connection_half_finished
,connection_partial_close
,connection_pending
,connection_rejected
,connection_reset
,connection_reused
,connection_state_remove
,connection_status_update
,connection_timeout
,scheduled_analyzer_applied
,new_connection
,new_connection_contents
- tcp_contents
- Type
event
(c:connection
, is_orig:bool
, seq:count
, contents:string
)
Generated for each chunk of reassembled TCP payload. When content delivery is enabled for a TCP connection (via
tcp_content_delivery_ports_orig
,tcp_content_delivery_ports_resp
,tcp_content_deliver_all_orig
,tcp_content_deliver_all_resp
), this event is raised for each chunk of in-order payload reconstructed from the packet stream. Note that this event is potentially expensive if many connections carry significant amounts of data as then all that data needs to be passed on to the scripting layer.- Parameters
c – The connection the payload is part of.
is_orig – True if the packet was sent by the connection’s originator.
seq – The sequence number corresponding to the first byte of the payload chunk.
contents – The raw payload, which will be non-empty.
See also:
tcp_packet
,tcp_option
,tcp_rexmit
,tcp_content_delivery_ports_orig
,tcp_content_delivery_ports_resp
,tcp_content_deliver_all_resp
,tcp_content_deliver_all_orig
Note
The payload received by this event is the same that is also passed into application-layer protocol analyzers internally. Subsequent invocations of this event for the same connection receive non-overlapping in-order chunks of its TCP payload stream. It is however undefined what size each chunk has; while Zeek passes the data on as soon as possible, specifics depend on network-level effects such as latency, acknowledgements, reordering, etc.
- tcp_multiple_checksum_errors
- Type
event
(c:connection
, is_orig:bool
, threshold:count
)
Generated if a TCP flow crosses a checksum-error threshold, per ‘C’/’c’ history reporting.
- Parameters
c – The connection record for the TCP connection.
is_orig – True if the event is raised for the originator side.
threshold – the threshold that was crossed
See also:
udp_multiple_checksum_errors
,tcp_multiple_zero_windows
,tcp_multiple_retransmissions
,tcp_multiple_gap
- tcp_multiple_gap
- Type
event
(c:connection
, is_orig:bool
, threshold:count
)
Generated if a TCP flow crosses a gap threshold, per ‘G’/’g’ history reporting.
- Parameters
c – The connection record for the TCP connection.
is_orig – True if the event is raised for the originator side.
threshold – the threshold that was crossed
See also:
tcp_multiple_checksum_errors
,tcp_multiple_zero_windows
,tcp_multiple_retransmissions
- tcp_multiple_retransmissions
- Type
event
(c:connection
, is_orig:bool
, threshold:count
)
Generated if a TCP flow crosses a retransmission threshold, per ‘T’/’t’ history reporting.
- Parameters
c – The connection record for the TCP connection.
is_orig – True if the event is raised for the originator side.
threshold – the threshold that was crossed
See also:
tcp_multiple_checksum_errors
,tcp_multiple_zero_windows
,tcp_multiple_gap
- tcp_multiple_zero_windows
- Type
event
(c:connection
, is_orig:bool
, threshold:count
)
Generated if a TCP flow crosses a zero-window threshold, per ‘W’/’w’ history reporting.
- Parameters
c – The connection record for the TCP connection.
is_orig – True if the event is raised for the originator side.
threshold – the threshold that was crossed
See also:
tcp_multiple_checksum_errors
,tcp_multiple_retransmissions
,tcp_multiple_gap
- tcp_option
- Type
event
(c:connection
, is_orig:bool
, opt:count
, optlen:count
)
Generated for each option found in a TCP header. Like many of the
tcp_*
events, this is a very low-level event and potentially expensive as it may be raised very often.- Parameters
c – The connection the packet is part of.
is_orig – True if the packet was sent by the connection’s originator.
opt – The numerical option number, as found in the TCP header.
optlen – The length of the options value.
See also:
tcp_packet
,tcp_contents
,tcp_rexmit
,tcp_options
Note
To inspect the actual option values, if any, use
tcp_options
.
- tcp_options
- Type
event
(c:connection
, is_orig:bool
, options:TCP::OptionList
)
Generated for each TCP header that contains TCP options. This is a very low-level event and potentially expensive as it may be raised very often.
- Parameters
c – The connection the packet is part of.
is_orig – True if the packet was sent by the connection’s originator.
options – The list of options parsed out of the TCP header.
See also:
tcp_packet
,tcp_contents
,tcp_rexmit
,tcp_option
- tcp_packet
- Type
event
(c:connection
, is_orig:bool
, flags:string
, seq:count
, ack:count
, len:count
, payload:string
)
Generated for every TCP packet. This is a very low-level and expensive event that should be avoided when at all possible. It’s usually infeasible to handle when processing even medium volumes of traffic in real-time. It’s slightly better than
new_packet
because it affects only TCP, but not much. That said, if you work from a trace and want to do some packet-level analysis, it may come in handy.- Parameters
c – The connection the packet is part of.
is_orig – True if the packet was sent by the connection’s originator.
flags – A string with the packet’s TCP flags. In the string, each character corresponds to one set flag, as follows:
S
-> SYN;F
-> FIN;R
-> RST;A
-> ACK;P
-> PUSH;U
-> URGENT.seq – The packet’s relative TCP sequence number.
ack – If the ACK flag is set for the packet, the packet’s relative ACK number, else zero.
len – The length of the TCP payload, as specified in the packet header.
payload – The raw TCP payload. Note that this may be shorter than len if the packet was not fully captured.
See also:
new_packet
,packet_contents
,tcp_option
,tcp_contents
,tcp_rexmit
- tcp_rexmit
- Type
event
(c:connection
, is_orig:bool
, seq:count
, len:count
, data_in_flight:count
, window:count
)
Generated for each detected TCP segment retransmission.
- Parameters
c – The connection the packet is part of.
is_orig – True if the packet was sent by the connection’s originator.
seq – The segment’s relative TCP sequence number.
len – The length of the TCP segment, as specified in the packet header.
data_in_flight – The number of bytes corresponding to the difference between the last sequence number and last acknowledgement number we’ve seen for a given endpoint.
window – the TCP window size.