Mac TCP Watcher 2.0, It Looks Good Mac TCP Watcher 2.0 (shareware, $10) Stairways Shareware You've followed the instructions of your ISP or network administrator, and your Internet or LAN connectivity finally works. But one day, disaster strikes. You can't get to your favorite web site, or your e-mail program complains about not being able to contact something called a DNS. Don't panic! Mac TCP Watcher provides a basic set of tools that can test the integrity of your network connection, and help pinpoint those annoying network glitches. Mac TCP Watcher Opening Window Starting Mac TCP Watcher will present you with a basic informational screen, as well as buttons which will let you perform individual tests. The basic information includes your Mac's IP address and host name, as well as statistics about the number of connections made and the amount of data sent and received since TCP/IP was started. If Mac TCP Watcher is unable to map your IP address to a host name, an error message will result. This may not be a problem, since not all installations map each IP address to a host name, or may use another mechanism such as an HTTP proxy to resolve host names.   The ping test is one of the most basic, and sends an ICMP (Internet Control Message Protocol) "echo" packet, which a properly configured and reachable host will always respond to. If you get responses to only some of your ping requests, or the response time is excessive, you may be dealing with network congestion. If you are using Open Transport, you can try to ping your own machine using the magic loopback address of 127.0.0.1. If you get no response when trying to ping your own machine, you have serious problems and should probably reinstall Open Transport. Ping Results Window The UDP (User Datagram Protocol) and TCP (Transmission Control Protocol) tests require that the remote machine either be a properly configured UNIX box, or another Mac running Mac TCP Watcher. If a ping test succeeds but either of these tests fail, a router or firewall somewhere on your network may not be properly configured. The DNS (Domain Name System) test verifies that the DNS server(s) that have been previously configured are doing their job. If you enter an IP address, the corresponding host name associated with this address will be reported. Likewise, entering a host name will report the IP address(es) associated with that name. Open Transport users can utilize the traceroute test to show all of the routers that a packet must pass through before reaching its final destination. If you are unable to contact a remote host, this feature can show you where the information is being held up. Finally, there's the Show Connection List feature, which offers real-time feedback on all UDP and TCP sessions. This is a great diagnostic and learning tool, helping you understand what your TCP/IP programs are doing behind the scenes. Mac TCP Watcher should be part of any Internet user's basic set of tools. The Show Connection List Window