topic Re: SSL inbound inspection in General Topics

SSL inbound inspection

Jafar_Hussain — Wed, 19 Aug 2020 19:57:08 GMT

Hi Team,

I am facing the issue in SSL decryption intermittently. For the transaction website.

traffic flow for the SSL inspection is:-

Outside user ------> Paloalto--------->Load balancer-------->Application server.

In the destination NAT translation, i have given the load balancer IP.

Condition A with SSL inspection:-

Once we apply SSL inspection we can see the application webpage is open properly but some time transfer page was showing blank.

We tried to do transactions multiple times and it was successful sometimes and sometimes stuck on-page.

Condition B without SSL inspection:-

Everything is working fine.

Troubleshooting:-

Below is the counter value:-

I just found this error in counter but not able to understand what is the exact issue.

Could you please give me any sugesion in this.

Re: SSL inbound inspection

BPry — Wed, 19 Aug 2020 20:14:12 GMT

@Jafar_Hussain,

What session_end_reason were you getting on the sessions that were giving an error? On your decryption profile, what options if any do you have checked under SSL Inbound Inspection?

Re: SSL inbound inspection

Jafar_Hussain — Wed, 19 Aug 2020 20:19:57 GMT

@BPry

When i login in website page the decryption showing traffic is decrypted. after login once i click any functionality like transaction the traffic is showing decrypt-error.

didn't apply any decryption profile, it is none.

Re: SSL inbound inspection

Jafar_Hussain — Thu, 20 Aug 2020 07:54:42 GMT

@BPry

I analyze the packet capture and found below:-

1 - Paloalto only support limited Elliptic curves which are received by server hello:-

bu in this packet capture i am not able to find any Elliptic curve detail.

Supported elliptic details are below:-

P-192 (secp192r1)
P-224 (secp224r1)
P-256 (secp256r1)
P-384 (secp384r1)
P-521 (secp521r1)

https://docs.paloaltonetworks.com/compatibility-matrix/supported-cipher-suites/cipher-suites-supported-in-pan-os-8-1/cipher-suites-supported-in-pan-os-8-1-decryption

2 - I have gone through the below documents and found the extension: extended_master_secret is same for client and server hello.
https://smartnets.wordpress.com/2016/11/07/palo-alto-firewalls-unable-to-decrypt-ssl-inbound-traffic/

But i am not sure what is the reason i am getting decryption error intermittently.

Re: SSL inbound inspection

Jafar_Hussain — Thu, 20 Aug 2020 10:48:01 GMT

@BPry

I want to add one more point, i have analyzed the counter again and found the below value:-

Number of ssl sessions can't be decrypted because of out of resources proxy_l2hdr_extended 13 1 info proxy pktpro

apart from this 9 other SSL inbound policy is working perfectly.