[xk3]

I have something similar--for deciding whether to try to connect locally or via remote address:

    Match host 10400 exec "timeout 1 nc -z 192.168.1.101 22 2>/dev/null"
        Hostname 192.168.1.101
        Port 22

    Host 10400
        Hostname myhost.duckdns.org
        Port 564