[ntp:hackers] ntpd send reply to port 123 though client request source port is not 123

Reeve Yang reeve.yang at gmail.com
Thu Oct 17 19:20:12 UTC 2013


Hi All,

I'm using ntp-4.2.4p4 as server and found a funny problem in
inter-complying test with extreme switches who run sntp-v1 as client. Those
guys are sending ntp request on non-standard source port, my server
receives the requests and send replies, but it sends with destination port
still as 123. Of course the client side complains not receiving replies!

I'm wondering whether ntp just use fixed port 123 disregarding the received
packets source port? This is a pretty common problem, so before I put any
patch on the source, I'd like to know more information about it. Have you
guys ever experienced the similar problem? How did you fix/work-around it?

Thanks.
- Reeve


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