Skip to main content


Showing posts from April, 2010

Identify other end PC...or OS!!!

IP packet contains n number of information within. One important protocol is TTL i.e. Time To Live. It is an eight-bit field helps prevent datagrams from persisting (e.g. going in circles) on an internet. This field limits a datagram's lifetime. It is specified in seconds, but time intervals less than 1 second are rounded up to 1. In latencies typical in practice, it has come to be a hop count field. Each packet switch (or router) that a datagram crosses decrements the TTL field by one. When the TTL field hits zero, the packet is no longer forwarded by a packet switch and is discarded. Typically, an ICMP message is sent back to the sender that it has been discarded. In addition to that there is a good reason to use this field, i.e. for identifying the other end PC, device or OS. How? Lets check: goto command prompt (in linux goto terminal) and use ping command to identify the availability of other end device. You will find : Here you can see the TTL (highlighted) value is 30 the