What does "warning, got duplicate tcp line" mean in the output of netstat?

The output value of 1 means they are enabled. These kernel parameters can be disabled with the following entries in /etc/sysctl.conf:

net.ipv4.tcp_tw_reuse = 0
net.ipv4.tcp_tw_recycle = 0

原文資料參考
http://kbase.redhat.com/faq/FAQ_80_6180.shtm

備註：：似乎沒啥用，網路上是有人說更新net-tool這套件可以解決，看來那天再來試試。