SSL Decryption: ERR_HTTP2_INADEQUATE_TRANSPORT_SECURITY

[mrkskhn]

Hi paloalto community,

we're currently still testing ssl decryption and discovered a new error, which I can't google to find a solution.

If we're visiting the following site, we get an "ERR_HTTP2_INADEQUATE_TRANSPORT_SECURITY" error. Site: https://www.1erforum.de/

See attached our configuration and ssl information without decryption enabled.

Firmware and Specs:

PA 850 - FW 9.0.5

Settings:

Decryption disabled:

Decryption enabled:

[kalolu]

So basically it seems that the only solution for this is limit the decryption my excluding ECDHE from Key Exchange Algorithms or enabling  Strip ALPN. I definitely hope that PA will consider putting this change from 10.x.x also back to 9.x.x.

Can anybody confirm exclusion of ECDHE or ALPN stripping had solve this issue for them?

[Nikolay-Matveev]

We have ended up with an EDL where we place the URLs that produce the likes of Chrome's 

ERR_HTTP2_INADEQUATE_TRANSPORT_SECURITY error. This EDL in its turn is used in a decryption rule with "Strip ALPN" option ticked in the decryption profile, and that rule is placed above our default decryption rule. Thus we still decrypt all these sites but downgrade them to HTTP1.1 - is not a big deal. We have ~13K web users and so far discovered only a handful of misbehaving websites... running 9.0.x. Hope this helps.

[neuadmin]

Could you share how you have the EDL configured?

[sebastianvd]

we ran into this issue too so following with curiousity

[Sec101]

same problem.  strip alpn fixes. Chrome is leading browser.   How can palo not have noticed this?