[DERBY-7107] NetworkServerControl fails to connect to server started on INADDR_ANY

• Type: Bug
• Status: Open
• Priority: Critical
• Resolution: Unresolved
• Affects Version/s: 10.14.2.0, 10.15.2.0
• Component/s: Network Server
• Urgency: Normal
• Issue & fix info: Known fix, Patch Available, Workaround attached
• Bug behavior facts: Seen in production
• Assignee: Unassigned
• Reporter: Holger Rehn
• Created: 16/Mar/21 12:59
• Updated: 20/Mar/21 19:54

Description

If starting a NetworkServerControl on INADDR_ANY (0.0.0.0) it also uses this address when connecting to the running server instance (e.g. in method ping(), ...).

Strictly speaking, INADDR_ANY isn't a valid target address. However, under normal circumstances, this works anyway. But if you have any "security" software in place that blocks such connections (Firewall or VPN, e.g. Cisco AnyConnect), you end up with an IOException: 

Could not connect to Derby Network Server on host 0.0.0.0, port 1527: Permission denied: connect.

One simple fix would be to explicitly check the host address 'hostAddress' in NetworkServerControlImpl.setUpSocket() and if this is INADDR_ANY, use 'localhost' instead.