A Basic UNIX Overview (big post with full details)

A Basic UNIX Overview (big post with full details)Introduction ------------ One of themost common operating systems in existance is Unix. Unix exists inmany different flavors, from Berkeley BSD to AT&T System V to SunOs. Basicworking knowledge of Unix is almost essential to a hacker, asit is the system a hacker is most likely to come across. If youintend to use the internet at all, or to do any serious explorationof Telenet, the ability to navigate through Unix is a necessity. (Unixis also the single most interesting system in existance: it'sjust fun to fuck with). Unix Logins ----------- Most Unixlogins look essentially the same. A general Unix login prompt lookssomething like this: connected tofive.finger.com login: That firstline is the system identifier. Although it's not at all essential towhat you are doing, it's good to know what system you are attemptingto log on to. The secondline is what typically identifies the system you are on as Unix. Almostall Unix systems greet a user with the same prompt: login:. Well,there's not much to do in Unix from the outside, and Unix systems aretypically fairly secure at this point. You may be able to obtain alist of users, or current users, by logging in as 'who', but other thanthat there are few functions available here. Unless youare on the internet, or have accounts specifically for the specificmachine you are on, the only way on to the system is to try the defaultpasswords. What are the default passwords? Unix systemscome installed with certain passwords automatically. In addition,some accounts must exist on a system. One such account is 'root'. Thisuser is the divine Kami of the Unix system... in short, an allaccess pass. Unfortunately, few systems allow root logins remotely,and even fewer leave 'root' unpassworded. Nevertheless, it's always wortha shot... try this: connected toren.stimpy.net login: root password: root invalidlogin login: well, nicetry anyways... other possible passwords for root include 'sysadmin','sys', 'admin'... you get the idea. You may also want to try thesepasswords with a single digit appended (added, idiot) to them... meaningthe password 'root' could be 'root1' or 'root2'. Aninteresting tip about passwords in general... many people that use passwordsunder 8 characters tend to add a digit or a non-alphanumeric character tothe password. This is done in order to hinder guessing, and to stoppassword breakers (more on this later). In this case, you may want totry adding a space before root... or even an ascii 255 to the end. Fortunately,there is more than one default password in a unix system... aquick list: sys sys bin bin daemon daemon rje rje setup setup uucp uucp/nuucp/anonymous nuucp uucp/nuucp/anonymous mountfsys mountfsys In theSystem ------------- Ok, at thispoint, I'm going to assume you've gotten past the login... as painfulas that may sound. Although Unix may be secure from the outside,without effort from the system administrators, the inside of the systemis not. First off,you'll likely by asked for a terminal. vt100 serves your purposessufficently, and it's typically the default, so hit enter. Now,hopefully, you have a prompt. There are many different types of unixprompts, some of which contain current directory information, some ofwhich are just a single character. Just don't panic when my examplesdon't look exactly like what you've got on your screen. The firstthing you *need* to do on the system is establish your tty paramters. Aseldritch and arcane sounding as this term may seem, it's actuallyquite simple... you need to tell the system what keys are going to dowhat. The commandto set these parameters is 'stty'. Watch: squinkyB ] sttyerase ^h squinkyB ] There... thatwasn't so bad, was it? Well, it's also pretty meaninglessto you, unless you have the ascii table memorized and are p