Linux Network Troubleshooting with ip, ss, dig, and curl
When a Linux service is “unreachable,” the failure can be in several different layers: the local interface, routing, a listening socket, DNS, a firewall, TLS, or the application itself.
Randomly restarting services makes diagnosis harder. A better approach is to move from local state outward and identify the first layer that does not behave as expected.
1. Confirm the interface and address Start with the addresses configured on the host:
