well, that definitely appears to be part of it. this is all on the corporate WAN, so we shouldn't be going through the proxy for this traffic, but wireshark revealed that firefox was using the proxy and successfully receiving data back from the JSS, while everything else was bypassing it and receiving nothing back- we do set up the proxy to bypass for internal hostnames.
So, removing the proxy bypass setting got telnet, safari, and the jamf checkJSSConnection command working again, but the test machines still don't seem to be able to communicate with the jss fully . . . jamf policy commands result in an unable to contact the JSS error. jamf enroll commands give the same. Running a quickadd package results in a claim that the JSS is not responding. So, progress but not a full solution.
Also, why does firefox ignore the proxy bypass settings? It is configured to use the system proxy settings, so I would have expected it to behave the same as safari.
