172.19.19.4. is between this range
172.16.0.0 - 172.31.255.255 and is therefore a LAN (Local area network) IP address.
It should be nothing to worry about, espically if its constant. Most definetly another machine on your network, unless of course its not meant to be there.
TCMP 4 is just a standard internet protocool used on networked machines.
QUOTE
The Internet Control Message Protocol (ICMP) is one of the core protocols of the Internet protocol suite. It is chiefly used by networked computers' operating systems to send error messages—indicating, for instance, that a requested service is not available or that a host or router could not be reached.
ICMP differs in purpose from TCP and UDP in that it is usually not used directly by user network applications. One exception is the ping tool, which sends ICMP Echo Request messages (and receives Echo Response messages) to determine whether a host is reachable and how long packets take to get to and from that host.
Sourced from Wikipedia, the rest of the article is located here : http://en.wikipedia.org/wiki/Internet_Cont...essage_ProtocolDo you have another machine on your network? If not this could be a router or hub of some kind.
If im wrong, anyone feel free to please correct me.