HTTP/1.1 503 Service Unavailable

[amunnam]

I configured proxy in my Application while integrating with Fortify SSC. If I am not enabling proxy everything works fine. I configured proxy on Fortify ssc. Following error is result from Fortify SSC Server:

HttpResponseProxy{HTTP/1.1 503 Service Unavailable [Server: squid/3.5.27, Mime-Version: 1.0, Date: Tue, 10 Mar 2020 18:17:16 GMT, Content-Type: text/html;charset=utf-8, Content-Length: 4157, X-Squid-Error: ERR_DNS_FAIL 0, Vary: Accept-Language, Content-Language: en, X-Cache: MISS from b556a8f038a5, X-Cache-Lookup: MISS from b556a8f038a5:3128, Connection: keep-alive] ResponseEntityProxy{[Content-Type: text/html;charset=utf-8,Content-Length: 4157,Chunked: false]}}

Am I missing something? Do I need to change any configuration setting on Fortify SSC server? 

[HansEnders]

Can you better describe the network topology and where the failure is occurring?

It seems that you are saying that some Application (e.g. Jira) you have connected to your SSC Server can reach the SSC Server URL fine with no Proxy configured, but that when you apply a Proxy setting (Squid proxy) to that Application, then the SSC Server returns a 503 error.  Is that correct?  Could you name the Application in question (and its purpose), and also share the details (or a sanitized copy) of the proxy entry being used?  For the network proxy in question, do you know if it requires user Authentication before it will connect the user through tot he target URL?

The error you posted includes a DNS error.  When a browser/Application is used through this Squid Proxy, where does the Name Resolution occur, on the Proxy or on a DNS Server elsewhere on the network?  Is this the same DNS Server used when you connect from that remote workstation when using no Proxy setting?

Furthermore, there appears to be some known issues with Squid when resolving host names.  Have you checked this with your network team?

• https://www.google.com/search?q=X-Squid-Error%3A+ERR_DNS_FAIL+0
• http://www.squid-cache.org/mail-archive/squid-users/200903/0102.html

SSC Server 19.20 is hosted on Tomcat 9.0.x, defaulting to HTTP on port 8080.  You can customize the port, and enable SSL in Tomcat.  If you have done that, you may need to check that the Proxy can manage the traffic properly.