Well, it is 10:30am on New Years Eve and I am stuck sitting at work wishing I was dead. So, I'll make you all suffer with me by writting these tutorials

What!? No protocol? I figured you guys would enjoy hearing the details behind using a very common function called TraceRoute. TraceRoute is achieved by using ICMP (we have read the other turorial right?). Regardless, this tools man job is to simply determine the path an IP packet takes from source to destination. How is this helpful? From a technical viewpoint it allows us to determine if a main path went down and you are stuck using the redundant backups that are usually slower (let's say the main router to the ISP blew up). A TraceRoute would give you piece of mind as well as evidence in case the ISP is not keeping up with the CIR. On a security side of things.....we can view TraceRoutes to determine the last hop before a proposed site (such as a router) and in a good guy scenerio....focus our attention to securing that box. After all, the last system to the demarc that we are actually in control of should be both monitored and rock hard with security. Ok, so here goes the details with TraceRoute.

TraceRoute uses ICMP packets to determine addressing and positioning of hops along a path to a destination. It starts of by setting the TTL (time to live) value at 1 and letting it fly. When the router at the first hop detects that the value would be set to 0 it drops the packet and sends an ICMP reply which includes the routers IP in the header. After this, the original machine bumps up the TTL value to 2 which allows the packet to pass by the first router and stop at the second (this router in turn does the same thing with dropping the packet and sending a reply). This process continues until the destination IP is reached. Awhile back I always thought that TraceRoute was a single continuous motion that simply had a flag that prompted routers to reply when pinged....but in reality it is a sequential order of pings with adjusted TTY values that determine the destination. Neat right? Well, hope it helps....any questions...let me know

Cordially,

Sp1d3r