topic Re: traffic segmenation affect app-id in General Topics

traffic segmenation affect app-id

Alex_Samad — Thu, 16 Jul 2020 01:54:52 GMT

So I am working through a ssl decrypt issue with PA support. I am being told that because the stream is being segmented - so not coming as 1500mtu packets. the PA can't work out what the stream is.

The implication is that app-id doesn't work properly unless you have full 1500mtu packets.

I thnk my SE is agreeing - not 100% sure.

I am a bit lost on this, cause I wouldn't have though segmentaiton would cause a problem expect for if there was a timeout

Re: traffic segmenation affect app-id

Thyrion — Thu, 16 Jul 2020 11:27:46 GMT

segmentation should only become an issue when there is such a large volume that the firewall is unable to properly reassemble the packets in a timely manner

you cold try to adjust the TCP MSS on the interface which could help prevent fragmentation, see if that solves the issue

Re: traffic segmenation affect app-id

Alex_Samad — Thu, 16 Jul 2020 21:07:27 GMT

well this is on a ssl hand shake the initial setup.

I go openssl s_client connect <ip>:443

that fails. I have been working with support for a while now. and they are saying cause their might be some segmenation happening that could affect the firewall interpreting the ssl handshake as some of the packets are not being processed !

I was rather suprised.

Re: traffic segmenation affect app-id

Thyrion — Thu, 16 Jul 2020 21:32:16 GMT

I'd push for more information and better troubleshooting, maybe even escalation

Fragmentation shouldn't be a big issue