Service outside of a firewall not working

[Serge Bianda]

I have a server outside of our firewall that needs to authenticate
thought our CAS server located inside of our firewall. Is there any port
that needs to be opened on the firewall? The server was previously
hosted in house, and was working fine, but then we moved it offsite, and
now the authentication is failing. The cas server is accessible from the
Internet though

 

Here is what we get on the tomcat error log:

 

Authentication attempt failedjavax.security.auth.login.LoginException:
Pre-authentication information was invalid (24)

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