Warning, got duplicate tcp line – netstat error and solution

Q. Whenever I run netstat command it bumps be back with an error, which read as follows:
tcp 0 0 ip-201-19-xxx-xxx.ip.s:http adsl-71-129-54-230.dsl:2249 TIME_WAIT
tcp 0 0 ip-201-19-xxx-xxx.ip.s:http ca-dstreet-cuda3-c6a-5:4380 TIME_WAIT
tcp 0 0 ip-201-19-xxx-xxx.ip.s:http ip72-199-249-17.sd.sd.:1845 TIME_WAIT
tcp 0 0 ip-201-19-xxx-xxx.ip.s:http cache-mtc-ad10.proxy.:59985 TIME_WAIT
warning, got duplicate tcp line
warning, got duplicate tcp line

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Although, everything is working fine but I am little worried about this error. How do I fix this error and what does it mean?

A. This is quite uncommon. This error indicating that client/server connection are rapidly closing and reconnecting to ip ip-201-19-xxx-xxx.ip on same port 80.

To fix this problem, open /etc/sysctl.conf and

# vi /etc/sysctl.conf

Append or modify text as follows:

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

Save the file and reboot the system. If particular client IP addresses causing this problem, use the iptables to drop the client IP or block IP with null routes.

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3 comments… add one
  • dave Mar 29, 2007 @ 8:23

    # Append or modify text as follows:

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

    I did like you said, but “warning, got duplicate tcp line” still happens. What does it mean actually. Where I can find more info about the matter?

  • Gagan Brahmi Jan 13, 2009 @ 14:00

    Nope.. This does not work…

  • Mac Jul 26, 2013 @ 21:43

    How do you remove user with smbpasswd command, I have been searching not able to find it any help/advice would be great.

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