our browser know which port he has to access?Now, the registered ports are those from 1024 through 49151. These ports are reserved for several programs. For example: ICQ (www.icq.com) reserves several ports for listening to various incoming events (messages, file transfers etc') on it.The dynamic and/or private ports are those from 49152 through 65535, and can be used by anyone for any given purpose.Important note about well-known ports: services(3) on these ports can be only ran by root, so inferior users won't start messing up with important ports.3. Service - a daemon(1) that allows everyone who connects to it (or a specific group of people. For example: anyone from this IP(9) range, everyone who knows the secret password etc') to use some kind of service.For example: a webserver such as the one described in section one on this chapter (the explanation regarding what is a port) is a service because it allows people to come in and ask for certain pieces of data.The simplest example of a service I can think of is "daytime". Daytime waits for incoming connections on port(2) 13 and when someone goes by it immedietly announces the current time on the computer that runs it (with no need from you to type in any commands or passwords or anything). Simple.4. Daemon banner - most daemons(1) give away some technical info to anyone who connects to them on some point. This information can be used by anyone who connects to that daemon simply for it to know how to interact with the daemon best (which daemon is it, what version, etc'), but it can also be used by hackers.Let's try connecting to port(2) 23 on someone.com (note: I've made up this hostname(10) and all the details regarding it simply to teach you about daemon banners. I really don't know whether there is such a hostname and whether the details I'm about to give you are correct). On port 23 you would usually find Telnet(19). Telnet is a service which at first asks you for a username and a...
