TCP: Options Error MSS In Non-SYN Packet
This protocol anomaly triggers when it detects a Maximum Segment Size (MSS) option in a non-SYN packet. The MSS option should appear only in SYN packets. While abnormal, these packets are harmless.
Extended Description
Because maximum packet size negotiation occurs only at the beginning of a session, MSS options should never be observed in non-SYN packets. Detection of MSS options in non-SYN packets could indicate a data transmission error has occurred, or that a malicious party is injecting malformed packets into a targeted network. The impact of such packets depends on the implementation of the TCP clients and servers that handle the packet.
References
Short Name
TCP:OPTERR:NONSYN-MSS
Severity
Info
Recommended
False
Recommended Action
None
Category
TCP
Release Date
04/22/2003
Supported Platforms
srx-branch-12.3
srx-19.3
srx-branch-19.3
vsrx3bsd-19.2
srx-branch-19.4
vsrx-19.4
mx-12.3
mx-19.4
vmx-19.4
mx-19.3
vsrx3bsd-19.4
srx-19.4
vsrx-12.3
vmx-19.3
vsrx-19.2
srx-12.3
Sigpack Version
3324
False Positive
Unknown