TLS Issue when attempting to connect to SNow

[Ngauthier]

Hello all,

I am currently developing a console application in C# in order to perform small tasks inside of a Service-Now Instance. While originally, this was working well, it seems that now the service-now instance can not longer be accessed by my server or any server on that domain. This is due to the fact that when these devices attempt to perform the TLS handshake, after the Client Hello from our system, the Service-Now instance sends a TCP reset and the connection closes. I have tested this with other instances we own and the issue does not present. All Servers on the domain I am testing from are affected, and there are multiple networks to this domain. The device I am developing the console app on is a MS Server 2019. If I attempt to navigate to the website I get the unsecure/outdated TLS method IE error message. I tried to rend a request with Postman as well without success. I have exported the code and ran it without any issue outside that domain.

My question is, has anyone had this issue before? We are getting the TCP reset from the instance practically immediately. Any more suggested tips for me to troubleshoot? My network guys say they see traffic pass through without issue.

[-O- · Accepted solution]

No problem.

Good that it worked out in the end.

[-O-]

Thanks!

I appreciate it 🙂

[Ngauthier]

I did already run a Wireshark on the server and confirm that TLS 1.2 was being used. I even specified it in my console app, if I try a different version of TLS it throws me back a different error

I can also confirm that I can ping the instance as well as telnet into it using ports 80 and 443, so traffic IS getting through, just wondering what kind of policy could potentially be blocking the handshake to that specific instance.

I am attempting to get in touch with Service-now to see if they can run a packed capture from the instance's side and see what they receive/send in regards to that handshake.