A routine for checking network services

A connection can fail at several different stages. Separating those stages makes a maintenance check repeatable and its result easier to understand.

Start with reachability

Record where the request starts and which service is being tested. A working connection from one network says little about a different network path.

Check identity separately

After the connection opens, verify the certificate chain, the requested hostname and the current time. Keep these checks enabled during routine maintenance.

Use a small transfer

A successful handshake establishes a connection but does not measure useful data transfer. Fetch a small known resource and check both the response and the received length.

Repeat after maintenance

After a service reload or system restart, open a fresh connection. An existing session may survive a change that prevents new sessions from starting.