Server doesn't bind to IP4 requested socket number, but works in IP6
I have a Java program that opens a ServerSocket.
netstat -tlpn shows that if I open port 20 (for example):
-- IP6 binds a TCP socket to :::20
-- IP4 binds a TCP socket 127.0.0.1:32000
This doesn't necessarily work right. Some clients can connect, others cannot.
This seems to have broken between fc22 and fc24.
I disabled selinux, to no effect. The process is running as root. I put it in a systemd unit file, which worked under the previous fc22 host.
What would cause binding to be mucked up that way?