How to correctly decrypt FTP (over TLS) traffic

JoseCortijo — Thu, 01 Dec 2022 15:56:44 GMT

Hi,

I am facing the common issue of Passive FTP (over TLS). Basically, the connection fails due to the dynamic ports assigned in the encrypted channel. It is clear that the solution is to configure PA to decrypt the traffic to identify the dynamic port and PA automatically (and temporarily) will open the traffic for that port.

But unfortunately, I could not find detailed instructions for the implementation.

https://knowledgebase.paloaltonetworks.com/KCSArticleDetail?id=kA10g000000ClEjCAK

I created a decryption rule for my only user with ANY in the service (see attachment) and the problem gets solved, but I didn't feel comfortable with the ANY so I tried filtering by FTP ports. I created a service called FTP Test with TCP 20 and 21 ports.

Doing this, the traffic did not match, didn't get decrypted and the FTPs connection failed to list the directory.

could you please help me out with the correct configuration?

Many thanks.

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Re: How to correctly decrypt FTP (over TLS) traffic

OtakarKlier — Fri, 02 Dec 2022 21:07:23 GMT

Hello,

You would need to select the port/service that the traffic is being seen as prior to decryption. Best practice would be to decrypt all traffic and have exceptions to bypass encryption.

Hope this helps.

topic How to correctly decrypt FTP (over TLS) traffic in General Topics

How to correctly decrypt FTP (over TLS) traffic

Re: How to correctly decrypt FTP (over TLS) traffic