tcpmssd - Utility to correct requested TCP receive segment size

Property Value
Distribution FreeBSD 12
Repository FreeBSD Ports Latest amd64
Package filename tcpmssd-1.1.txz
Package name tcpmssd
Package version 1.1
Package release -
Package architecture amd64
Package type txz
Category net
Homepage -
License -
Download size 7.38 KB
Installed size 20.76 KB
tcpmssd was written by Ruslan Ermilov <> based on work
done by Patrick Bihan-Faou <>.
tcpmssd is a divert(4) program that adjusts outgoing TCP data so that
the requested segment size is not greater than the amount allowed by
the interface MTU.
This is necessary in many setups to avoid problems caused by routers
that drop ICMP Datagram Too Big messages.  Without these messages,
the originating machine sends data, it passes the rogue router then
hits a machine that has an MTU that is not big enough for the data.
Because the IP Don't Fragment option is set, this machine sends an
ICMP Datagram Too Big message back to the originator and drops the
packet.  The rogue router drops the ICMP message and the originator
never gets to discover that it must reduce the fragment size or drop
the IP Don't Fragment option from its outgoing data.
===>   NOTICE:
The tcpmssd port currently does not have a maintainer. As a result, it is
more likely to have unresolved issues, not be up-to-date, or even be removed in
the future. To volunteer to maintain this port, please create an issue at:
More information about port maintainership is available at:


Package Version Architecture Repository
tcpmssd-1.1.txz 1.1 i386 FreeBSD Ports Quarterly
tcpmssd-1.1.txz 1.1 amd64 FreeBSD Ports Quarterly
tcpmssd-1.1.txz 1.1 i386 FreeBSD Ports Latest
tcpmssd - - -


Type URL
Binary Package tcpmssd-1.1.txz
Source Package net/tcpmssd

Install Howto

Install tcpmssd txz package:

# pkg install tcpmssd

See Also

Package Description
tcpproxy-1.2.txz Simple TCP connection proxy for IPv4 and IPv6
tcpreen-1.4.4_3.txz Simple TCP session re-engineering tool
tcpreplay-4.3.2.txz Tool to replay saved packet capture files
tcpser-1.0.r12.txz TCPSER turns serial port into an emulated Hayes compatible modem
tcpsg-0.0.2.txz Simple TCP port forwarder
tcpshow-1.74_2.txz Decode tcpdump(1) output
tcpslice-20140407.txz Tool for extracting portions of pcap files
tcpsplit-0.2.txz Breaks a libpcap trace along TCP connection boundaries
tcpstat-1.5.txz Program to report various network statistics
tcptestsuite-0.0.2.txz Network stack test suite
tcptrace-6.6.8.txz TCP dump file analysis tool
tcptraceroute-1.5beta7.txz Traceroute implementation using TCP packets
tcptrack-1.4.2_3.txz Packet sniffer that displays TCP information like top(1)
tcpview-1.0_7.txz Motif-based TCP/IP protocol analyzer
tcpwatch-1.3_4.txz TCP monitoring and logging tool with support for HTTP 1.1