I am trying to set up a TLSv1.3 / TLSv1.2 webserver behind a palo firewall with ssl inbound decryption.
However i seem to get a lot of ssl errors and the website does not work if specific ciphers are not listed first...
For one I would like to understand why that is and even ciphers listed here have issues: https://docs.paloaltonetworks.com/compatibility-matrix/supported-cipher-suites/cipher-suites-support...
Basically, what should the apache config look like for the palo to be able to decrypt the traffic, yet still have the highest possible security (e.g. as rated by https://www.ssllabs.com/ssltest/) ?
That wont fully work with TLSv1.2 and TLSv1.3 at the same time, I figured out how to do this a while back and gave an example config to TAC but here it is as reference for everyone...
To support both TLSv1.2 and TLSv1.3 at the same time and use secure ciphers, I found the following to work the best:
SSLOpenSSLConfCmd ECDHParameters brainpoolP256r1
SSLOpenSSLConfCmd Curves secp521r1:secp384r1:prime256v1
SSLOpenSSLConfCmd SignatureAlgorithms ECDSA+SHA512:ECDSA+SHA384:ECDSA+SHA256:RSA+SHA512:RSA+SHA384:RSA+SHA256:rsa_pss_rsae_sha512:rsa_pss_rsae_sha256
ssl_conf_command ECDHParameters brainpoolP256r1
ssl_conf_command Curves secp521r1:secp384r1:prime256v1
ssl_conf_command SignatureAlgorithms ECDSA+SHA512:ECDSA+SHA384:ECDSA+SHA256:RSA+SHA512:RSA+SHA384:RSA+SHA256:rsa_pss_rsae_sha512:rsa_pss_rsae_sha256
this needs a certain minimum version of openssl and apache/nginx 🙂
a bit cumbersome but oh well...
it fulfills palos restrictions/requirements while still offering all compatible and secure ciphers and being compatible to modern browsers (I checked this for TLSv1.2 and TLSv1.3 only as those were the only secure ones).
if anyone does the same in other flavors like lighttpd, haproxy or any other platform that might need customization, please be so kind and post an example here as well so others can adapt it into their configs 🙂
There is nothing in the sslmgr.log and nothing but the General errors in the UI
the only ciphers that seem to work with Palo decryption on TLSv1.2 and Chrome/Firefox are these two:
all others error out even if those ciphers above are also available but not listed first (SSLHonorCipherOrder is set to off)
but with these ciphers which are considered weak, i dont even get forward secrecy and therefore the rating is down to B...
I wonder why the following ciphers dont work:
ECDHE-RSA-AES256-GCM-SHA384:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-RSA-CHCHA20-POLY1305-SHA256:CHACHA20-POLY1305-SHA256 or the ECDHE-ECDSA ones which are listed as supported but not shown in the decryption profile settings
anyone have an idea or even just an idea how to troubleshoot this further?
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