Before early September 2020 our complete program library using Java, jdbc and postgresql worked fine on a new Mac Mini and other machines. Then we started getting connection timeouts from all Java programs running on the Mac Mini accessing any server except 127.0.0.1. This was around the time we upgraded to Mac OS 10.15.7.
We wrote a simple test Java program and ran the same object code on Mac OS Catalina 10.15.7 on the Mac Mini, a Windows 10 VM running on Parallels running on the same Mac Mini, and a Debian 9.8 VM also running on Parallels also running on the same Mac Mini and a MacBook Pro also running 10.15.7.
Results summary:
- Mac OS 10.15.7 on the Mac Mini fails to connect to any address except to 127.0.0.1.
- Windows 10 works as expected
- Debian 9.8 works as expected and identically to Windows 10.
- When running on a MacBook Pro running the same operating system (Mac OS 10.15.7) everything works as expected.
There are some differences in behaviour between JDBC versions. The latest (postgresql-42.2.16.jar) hangs on the Mac Mini whereas postgresql-9.0-801.jdbc4.jar returns an SQLException after timing out.
Using portscan on the Mac Mini shows that port 5432 is open and accessible on the target servers.
psql connects to the various servers OK including to the MacMini itself using both 127.0.0.1 and its external ip address.
pgAdmin also connects OK.
Thus it would appear there is an issue with the JDBC driver running under Mac OS 10.15.7. We have tried with Apple to investigate whether there is a permissions issue but made no progress.
Has anybody else encountered this problem ?
David Gradwell