I am having an issue getting NTP from an inside host to a host on the outside.
My inside host is on an RFC 1918 address and it has a static source NAT translation to a registered internet address to any destination. My inside source is sending the NTP packets out with a source port of UDP 123 and also a destination port of UDP 123
I have access list rules in place on the inside interface to permit the traffic and can see the counters increasing with each attempt from the inside host.
When I try to packet trace the connectivity on the ASA using asdm the flow seems OK, however the output interface is showing as unknown.
In certain TCP peering, you'd need the TCP ports to be enabled as well. With this, all I can think of is the Public NTP Server 220.127.116.11 that you're pointing to could be the cause here. Have you tried pointing to other Public NTP Servers e.g. 18.104.22.168, 22.214.171.124 and 126.96.36.199?
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Ramraj Sivagnanam Sivajanam
Technical Specialist/Service Delivery Manager – Managed Service Department
Thanks for the reply, all connectivity is fine and the router we are using as a client is sending UDP requests only.
I have managed to solve the unknown output issue, I was missing an ip verify reverse path interface outside command. So now the packet trace seems to work fine however my host on the inside will still not sync to the public server.
The public server I am using is :
ntp2.sandvika.net 188.8.131.52 Telehouse Europe, London E14 UK NTP V4 secondary Sun UltraSPARC Solaris 8
The ip verify reverse path interface outside command only appears to affect the first packet in the flow.
If I clear the connections, then try a packet trace the output is exactly what I expect, once the flow idles out the second flow come back with the unknown output interface as seen in the screenshot above.
Table of ContentsIntroductionVersion HistoryPossible Future
UpdatesDocuments PurposeNAT Operation in ASA 8.3+ SectionsRule Types
Network Object NATTwice NAT / Manual NATRule Types used per SectionNAT
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