TCP Tuning Guide

Version 1.0 - Last published Nov 30, 2005

System Tuning

TCP Background Linux FreeBSD Solaris Windows Mac OSX Other

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FreeBSD Tuning

Add these to /etc/sysctl.conf and reboot.
kern.ipc.maxsockbuf=16777216
net.inet.tcp.rfc1323=1
net.inet.tcp.sendspace=1048576
net.inet.tcp.recvspace=1048576
For more info see the: FreeBSD Network Tuning Performance Tuning Guide

FreeBSD version before 4.10 don't have SACK implemented, which limits its throughput considerably compared to other operating systems. You should upgrade to 4.10 or higher.