Non connect() TCP ping

[jbrendel]

Currently, we open a socket to a TCP port. SYN + SYN_ACK + ACK. This results in an established connection to the host, which in turn may result in a log entry on that host. This is not desirable.

Instead, we should terminate the connection right after receipt of a SYN_ACK with an RST. This will not result in log entries being created.