topic Re: VPN Decaps and Decrypts in Network Security

VPN Decaps and Decrypts

Jon Eyes — Fri, 21 Feb 2020 16:10:52 GMT

Hi Everyone,

Any idea what could be causing this?

#pkts encaps: 1181, #pkts encrypt: 1181, #pkts digest: 1181
#pkts decaps: 1181, #pkts decrypt: 0, #pkts verify: 0

we usually encounter encaps/encrypts are incrementing, but no decaps/encrypt -- usually is nat issue, but this one is different.

Advance thanks

Re: VPN Decaps and Decrypts

balaji.bandi — Sun, 02 Sep 2018 08:30:07 GMT

Look at both the device log output and compare config, This could happen when there's a route problem, NAT problem, or some sort of VPN filter.

Check the tunnel configuration on both the devices and check the is the Tunnel up ?

show crypto isakmp sa

show crypto ipsec sa

Re: VPN Decaps and Decrypts

Mohammed al Baqari — Mon, 03 Sep 2018 07:42:05 GMT

Make sure that return traffic is routed over the crypto interface. Also,
run a packet trace while the SA is up to see of the return packet will get
encrypted by responding device or not

Re: VPN Decaps and Decrypts

Jon Eyes — Tue, 04 Sep 2018 00:50:26 GMT

Hi,
It worked after we reconfigured and retyped the corresponding tunnel-group.. exactly the same.
We are using pre-shared key, not sure it was the key, but a mismatched key should be visible in the debug, and tunnel should not form from the start. This one the tunnel stood up and was stable, it's just the decrypt is not incrementing
Thanks for the input though

Re: VPN Decaps and Decrypts

Jon Eyes — Tue, 04 Sep 2018 00:52:26 GMT