libxt_tcpmss.man revision 3943ebf3493dac6fb135c9ed4a45750d8cdcdb82 
1This matches the TCP MSS (maximum segment size) field of the TCP header.  You can only use this on TCP SYN or SYN/ACK packets, since the MSS is only negotiated during the TCP handshake at connection startup time.
2.TP
3.BI "[!] "--mss " value[:value]"
4Match a given TCP MSS value or range.
5