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NTP traffic blocked by ASA 5510

Posted on 2009-04-22
Medium Priority
Last Modified: 2013-12-05
When I tried to sync the time with the external NTP server with my server which has IP of, I see my server's NTP client software is polling data forever.
I checked the firewall and I see the following message.
4      Apr 22 2009      08:25:34      419002       Duplicate TCP SYN from inside: to outside: with different initial sequence number

Please help me.

Question by:atlasdev
LVL 15

Expert Comment

ID: 24211366
Do you know if the external server actually uses TCP?  I think just about every implementation I've ever seen is using UDP..
Maybe you can flip this on the client and try?

If I try to telnet to that server's IP port 123 it just times out.. so it's at least not publically available for TCP.

Accepted Solution

atlasdev earned 0 total points
ID: 24217768
I dont know why. But after I reboot the server. This error message is gone.....
anyway, the problem is fixed by a simple reboot of the server....

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