Guide / Network
Network Diagnostics
Troubleshoot connectivity from DNS to the application layer without guessing.
DNS
dig example.com
getent hosts example.com
Routes
ip route
ip -br addr
Connectivity
ping -c 4 1.1.1.1
curl -4 https://ifconfig.me
TCP listeners
ss -lntup
HTTP
curl -I https://example.com
curl -vk https://example.com/
The useful approach is to move through the stack one layer at a time: name resolution, routing, TCP, TLS, HTTP and finally the application.