Network troubleshooting commands
Get the ping, port, traceroute, DNS, curl, TLS, routing, MTU and packet capture commands for Linux, macOS or Windows, with each flag explained.
Runs locally. Nothing you paste leaves this tab.
Also useful
Command not found?
Inside a container running as root, drop sudo.
Work up the layers
Most “the network is down” problems are one of these. Check them in order and stop at the first one that fails.
- DNS: does the name resolve, and to the address you expect? Compare the system resolver with a public one.
- Route: does traffic for that address leave through the interface you expect (VPN, not Wi-Fi)?
- TCP: is the port open? Refused means nothing listens there; timed out means a firewall drops it.
- TLS: is the certificate valid for the name, not expired, and sent with its intermediate?
- HTTP: what status and headers come back, and which step is slow?
A failed ping proves little: many networks block ICMP. Test the port the application uses instead.