Performance monitoring

command availability Explanation
ping <URL> base system Measure connection latency and reliability
speedtest apt install speedtest-cli Get connection’s upload and download speed

SSH

command Explanation
ssh -vT Get a bunch of diagnostics for a connection that isn’t working
eval `ssh-agent -s` then ssh-add Add SSH passphrase, so you are not repeatedly asked for it.

Renabling RSA Some old servers require this deprecated protocol. Re-enable it on a host-by-host basis by adding this to ~/.ssh/config

Host willslab.org.uk
    User andy
    PubkeyAcceptedAlgorithms +ssh-rsa
    HostkeyAlgorithms +ssh-rsa