TCP Maximum Segment Size Chain¶
This module contains the MSSChain flow analysis chain which can be used by PATHspider’s Observer for recording TCP Maximum Segment Size details.
- class pathspider.chains.mss.MSSChain[source]¶
This flow analysis chain records details of the TCP Maximum Segment Size (MSS) option in the flow record. It will determine the length and value of the field if present in SYN packets.
Field Name
Type
Meaning
mss_len_fwd
int
Length of the MSS option field including kind and length in the forward direction.
mss_len_rev
int
Length of the MSS option field including kind and length in the reverse direction.
mss_value_fwd
int
Value of the MSS option field in the forward direction.
mss_value_rev
int
Value of the MSS option field in the reverse direction.
- new_flow(rec, ip)[source]¶
For a new flow, all fields will be initialised to
None
.- Parameters
rec (dict) – the flow record
ip (plt.ip or plt.ip6) – the IP or IPv6 packet that triggered the creation of a new flow record
- Returns
Always
True
- Return type
bool
- tcp(rec, tcp, rev)[source]¶
Records TCP Maximum Segment Size Details.
- TCP Maximum Segment Size
The TCP options will be parsed for the MSS option for all SYN packets. If the option is found, the length and value for the option will be recorded in the flow.
- Parameters
rec (dict) – the flow record
tcp – the TCP segment that was observed to be part of this flow
rev (bool) – True if the packet was in the reverse direction, False if in the forward direction
- Returns
Always True
- Return type
bool