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Block NTP requests

Discussion in 'Tomato Firmware' started by FlashSWT, Jun 8, 2010.

  1. FlashSWT

    FlashSWT LI Guru Member

    Hey gang, what would be the easiest way to block (at the router level) a specific computer on my network from making an NTP time request?

    Alternatively how about blocking requests to a specific time server from any machine on the network?

    Thanks for any help.
  2. rhester72

    rhester72 Network Guru Member

    I am assuming in both cases the NTP server is external to your network. Place in the Firewall script.


    iptables -t filter -A wanout -s <local computer IP> --dport 123 -j DROP


    iptables -t filter -A wanout -d <specific external time server> --dport 123 -j DROP

  3. but2002

    but2002 Networkin' Nut Member

    Why would you want to block timeserver servers?
  4. FlashSWT

    FlashSWT LI Guru Member

    Thanks Rodney, figured it be an easy solution.

  5. mstombs

    mstombs Network Guru Member

    when you are trying to trick some old licensed software/game into running while it thinks the license is still valid?
  6. FlashSWT

    FlashSWT LI Guru Member

    Yep, trying to squeeze a little more life out of the Windows 7 Release Candidate. Another month and I won't need Windows anymore at all so no reason to drop the $140.

    Turns out it didn't matter, even after it "expired" it still works just fine, only with a black desktop and a "not valid" messages in the corner.

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