URL:
Reporter RHNID:
Section: -
Language: en-US (English)
Workaround:

Description: The Tang service runs as tangd.socket - it's an xinetd-like service that launches on demand. When enabled, the systemd PID 1 process listens on 80/tcp for connections like xinetd does, and if there's a connection it starts tangd dynamically.

If this is still running on a system and a student tries to start the httpd.service, it may fail with an error that it can't bind to 0.0.0.0:80 and [::]:80 (because systemd is holding the port for tangd).  To diagnose this, use "ss -tlpn" or "netstat -tlpn" and see what service is running on 80/tcp.

The confusing thing is that systemd (PID 1) will be holding the port in this case, and you may not immediately realize why it's doing that.

If it's systemd, you can run

[root@host ~]# systemctl list-sockets
LISTEN                            UNIT                            ACTIVATES
[::]:80                           tangd.socket

and it will show you if the tangd.socket is listening on that port.  If that's the case, run

systemctl stop tangd.socket; systemctl disable tangd.socket

Note that this may interfere with NBDE operation and automatic device decryption on systems using that Tang server for authentication.