=============================================================================== rush2112 pRESENTS a hale pRODUCTION h ACKERS a GAINST l AW e NFORCEMENT cALL hale hQ. (619)660-67XX aCTIVE hale MEMBERS ARE: rIPPER, tRASHMAN, rUSH2112. tHE uNDERGROUND nEWSLETTER: vOL i. iSSUE i, pART i =============================================================================== nOTE: fEEL FREE TO DISTRIBUTE THE FILE PROVIDED NONE OF ITS CONTENTS OR CREDITS ARE CHANGED. tOPIC: a gUIDE TO uNIX sYSTEMS, pART i. dATE: sEPTEMBER 1, 1989. fOREWORD: tHIS FILE IS COMPILED FROM MY EXPERIENCES ON BOTH bsd AND sYS v uNIX ON vax 750/780 MAINFRAMES, at&t 3b20 AND pYRAMID tECHNOLOGY'S MAINFRAMES. iN TODAY'S WORLD, AS A HACKER, YOU ARE NOTHING UNLESS YOU LEARN SOME OF THE MORE POPULAR OPERATING SYSTEMS AROUND USED ON MINIS, MAINFRAMES, SUPER- COMPUTERS AND THE LIKE. iN THIS FILE i WILL ATTEMPT (TO THE BEST OF MY ABILITY) TO INTRODUCE YOU TO ONE OF THOSE OPERATING SYSTEMS - NAMELY - THE WORLD OF uNIX. iT IS HOPED THAT BY READING THIS FILE YOU CAN PICK UP PERHAPS ENOUGH OF A WORKING KNOWLEDGE SO THAT IF BY CHANCE IN YOUR HACKING EXPLOITS YOU COME ACROSS A uNIX SYSTEM (AND YOU WILL) YOU'LL KNOW WHAT TO DO. tHERE IS no way TO COVER EVERYTHING ABOUT uNIX IN A FILE SO THIS WILL BE THE FIRST OF MANY THAT i HOPE TO RELEASE IN THE FUTURE. iF i FIND THERE ARE STUFF i HAVE NOT MENTIONED i WILL WRITE MORE FILES AS NEEDED. iN pART ii, i PLAN TO GIVE YOU A TUTORIAL ON WHAT TO DO WHILE YOU'RE ON-LINE IN REGARDS TO HACKING AND USING ESSENTIAL SYSTEM UTILITIES. hAVE FUN. uSUALLY (UNLESS MODIFIFIED BY THE SYSTEM ADMINISTRATOR OR ONE WITH SUCH PRIVILEGES), YOU CAN TELL IF YOU'VE CONNECTED TO A uNIX SYSTEM OF SOME TYPE BY THE LOGIN PROMPT WHICH LOOKS LIKE THIS: LOGIN: pRETTY SIMPLE HUH? aNYWAY, THAT IS THE STANDARD LOGIN PROMPT, IT MAY OR MAY NOT BE PRECEDED BY A MESSAGE TELLING YOU WHAT TYPE OF uNIX OR SYSTEM YOU HAVE CONNECTED TO. iF YOU TRY TO LOGIN WITH AN ILLEGAL LOGIN NAME AND/OR AN ILLEGAL PASSWORD THE SYSTEM WILL RESPOND AS SUCH AND AS YOU TO TRY AGAIN: LOGIN:HACKER PASSWORD: LOGIN INCORRECT LOGIN: (nOTE THE PASSWORD IS NOT ECHOED IN ANY FORM) iN pART i OF THIS uNIX TUTORIAL i'D LIKE TO START WITH AN OVERVIEW OF THE uNIX SYSTEM BEFORE i GET INTO SOME OF THE MORE INTERESTING STUFF (SO BEAR WITH ME ALL YOU uNIX EXPERTS). tHEN i WILL GO THROUGH THE LOGIN PROCESS AND THE /ETC/PASSWD FILE AND HOW IT IS STRUCTURED. tHIS WILL NOT BE AN IN-DEPTH LOOK AT ALL, MERELY AN OVERVIEW. sOME DAY i WILL WRITE AN IN-DEPTH STUDY TO ACCOMPANY THIS FILE AND THE FILES THAT FOLLOW FOR THE MORE ADVANCE USER/HACKER. tHERE ARE BASICALLY 2 TYPES OF uNIX SYSTEMS THAT YOU WILL MOST LIKELY COME ACROSS. tHEY ARE: i. bsd uNIX - FROM uc bERKELEY'S (b)ERKELEY (s)OFTWARE (d)ISTRIBUTORS ii. sYSTEM v unix - FROM at&t (HOW NICE - i KNOW ALL YOU PHREAKERS ARE SMILING!) (oTHER SPINOFF'S OF THE ABOVE 2 WILL NOT BE DISCUSSED - SUCH AS uLTRIX, mINIX, xENIX, ETC...) tHEY ARE ALIKE IN MANY RESPECTS BUT BOTH HAVE THEIR DIFFERENCES, HENCE THEIR ARE ADVANTAGES AND DISADVANTAGES TO BOTH OF THE SYSTEMS, bsd AND sYS v. pERHAPS THE MAIN DIFFERENCE BETWEEN THE TWO ARE THE DEFAULT SHELL THAT EACH USES AS THE USER INTERFACE TO THE SYSTEM UTILITIES. bsd uNIX DEFAULTS TO THE CSH (c-sHELL) WHILE at&t'S sYS v USES THE SH (bOURNE SHELL). bUT ON BOTH OF THESE SYSTEMS BOTH SHELL TYPES ARE AVAILABLE TO THE USER. a THIRD OPTIONAL SHELL WHICH IS ALSO PRETTY POPULAR IS THE KSH (kORN SHELL). tHE WAY TO RECOGNIZE THE DEFAULT SHELLS WHEN YOU SEE THEM IS BY THEIR DEFAULT PROMPT. tHE CSH USES THE % SYMBOL AS THE PROMPT WHILE THE SH USES THE $ SYMBOL AS THE PROMPT. nOW LET'S TALK ABOUT FILES, SHALL WE? tHE most IMPORTANT FILE OF ALL ON any unix SYSTEM IS THE PASSWORD FILE. tHIS FILE HOLDS INFORMATION ABOUT ALL THE ACCOUNTS ON THE SYSTEM, PASSWORDS, AND OTHER INFORMATION. wITHOUT THIS FILE NO ONE CAN LOG IN AND USE THE SYSTEM. yOU CAN FIND THIS FILE ON ANY SYSTEM IN THE /ETC DIRECTORY. iT IS CALLED SIMPLY 'PASSWD'. tHE FULL PATHNAME IS /ETC/PASSWD (OF COURSE). tHE /ETC/PASSWD FILE IS STUCTURED AS SUCH: eACH USER HAS AN ENTRY IN THE PASSWD FILE THAT HOLDS HIS ACCOUNT INFORMATION. aMONG THE INFORMATION INCLUDED ON EACH USER ENTRY LINE IS HIS LOGIN NAME, HIS PASSWORD (ENCRYPTED), HIS USER ID, HIS GROUP ID, HIS HOME DIRECTORY, HIS NAME, AND HIS STARTUP PROGRAM IF ANY. bASICALLY IT LOOKS SOMETHING LIKE THIS: ------------------------ sAMPLE /ETC/PASSWD FILE -------------------------- gENERAL FORMAT OF EACH ENTRY: LOGIN:PASSWORD:USER-id:GROUP-id:INFO:HOME DIRECTORY:STARTUP PROGRAM ROOT:aRLLZ76dNQ:0:0:tHE & OF aLL eVIL:/:/BIN/CSH JSMITH:yI83AMQ9:102:100:jOHN sMITH:/USR/JSMITH:/BIN/SH WHO::99:500:wHO'S ON:/USR/UCB:/BIN/WHO DAEMON:R6eEU:1:1:tHE devil HIMSELF:/ETC:/BIN/CSH BIN:MB033YT:3:3:tHE kEEPER OF THE fLAME:/ETC:/BIN/CSH INFO::508:501:lIBRARY USER GROUP:/USR2/INFO:/USR2/BIN/RSH ..... ..... [ AND SO ON ] ..... ---------------------------------------------------------------------------- nOW WE'LL EXAMINE EACH ENTRY. rEMEMBER THAT EACH FIELD IS SEPARATED BY THE COLON. sO IN THE FIRST ENTRY IN /ETC/PASSWD GIVEN ABOVE, WE CAN TELL THE FOLLOWING ABOUT THE ENTRY. LOGIN NAME IS: ROOT pASSWORD (ENCRYPTED): aRLLZ76dNQ uSER id: 0 gROUP id: 1 iNFO (USUALLY OWNER): ROOT hOME dIRECTORY: / sTARTUP pROGRAM: /BIN/SH tHE SECOND ENTRY IN /ETC/PASSWD LOOKS LIKE THIS: LOGIN NAME IS: JSMITH pASSWORD (ENCRYPTED): yI83AMQ9 uSER id: 102 gROUP id: 100 iNFO (USUALLY OWNER): jOHN sMITH hOME dIRECTORY: /USR/JSMITH sTARTUP pROGRAM: /BIN/SH bUT NOW YOU GET THE GENERAL FORMAT...SO LET'S DISCUSS SOME THINGS ABOUT THE FIELD. i. tHE LOGIN FIELD tHIS IS THE LOGIN NAME THAT YOU USE TO LOGIN AT THE PROMPT OF THE uNIX SYSTEM. dURING THE LOGIN PROCESS, AFTER YOU ENTER THE LOGIN AND THE PASSWORD THE SYSTEM WILL THEN CALL ROUTINES TO SEARCH THE 1ST FIELD OF EACH ENTRY IN /ETC/PASSWD TO SEE IF ANY LOGIN NAMES MATCH UP WITH THE ONE YOU HAVE GIVEN IT. iF NONE EXISTS IT WILL REPORT THE "LOGIN INCORRECT" MESSAGE AND START PROMPTING FOR A NEW LOGIN NAME AND NEW PASSWORD. ii. tHE pASSWORD FIELD iF THE LOGIN NAME IS VALID, uNIX THEN TAKES YOUR PASSWORD ENTRY AND ENCRYPTS IT THEN COMPARES IT AGAINST THE ENCRYPTED PASSWORD IN THE 2ND FIELD OF THE LOGIN NAME ENTRY (SEE i. tHE LOGIN FIELD). iF THE TWO PASSWORDS MATCH UP, THE LOGIN PROCESS WILL CONTINUE, OTHERWISE THE "LOGIN INCORRECT" MESSAGE WILL BE DISPLAYED. i'LL EXPLAIN LATER WHAT GOES ON WHEN COMPARISONS OF THE ENCRYPTED PASSWORDS TAKE PLACE. iF THE pASSWORD fIELD CONTAINS NULL :: THEN NO PASSWORD IS NEEDED AND THE SYSTEM LOGS YOU INTO THE HOME DIRECTORY AND EXECUTES THE STARTUP PROGRAM. iF THE pASSWORD fIELD CONTAINS :,.: THEN UPON LOGIN THE SYSTEM WILL RUN THE PASSWD UTILITY AND ASSIGN THAT ACCOUNT A PASSWORD. (tHIS IS NICE IF YOU'RE A SYSTEM ADMINISTRATOR, YOU CREATE AN ACCOUNT FOR YOUR FRIEND THEN PUT THE ",." IN THE PASSWORD FIELD AND HE'LL SET HIS OWN PASSWORD UPON LOGIN. iii. tHE uid (uSERid) FIELD iF EVERYTHING IS CORRECT (LOGIN NAME AND PASSWORD) THEN THE SYSTEM PROCEEDS TO PUT YOUR IN YOUR HOME DIRECTORY. yOU ARE THEN GIVEN A uid FROM YOUR ENTRY IN THE /ETC/PASSWD FILE. aLL uid'S FALL IN THE RANGE 0-65535 WITH 0 AS THE SUPERUSER uid (SEE /ETC/PASSWD EXAMPLE). tHE SYSTEM RESERVES uid 0-99 FOR SPECIAL ACCOUNTS. uid'S ARE USED BY THE SYSTEM AND ITS UTILITIES TO CONTROL BOTH ACCESS LEVELS AND FILE OWNERSHIP (AS DETERMINED BY THE LS UTILITY - MORE ON THAT LATER). iv. tHE gid (gROUPid) FIELD tHE gROUP id IS USED TO ASSOCIATE THE USER WITH A CERTAIN GROUP, USED BY uNIX PRIMARILY FOR ACCESS LEVELS AS DETERMINED BY FILE PROTECTIONS. (I.E. A MEMBER WHO IS NOT IN A GROUP CAN NOT GET GROUP PRIVILEGES ON FILES FOR THAT GROUP, EVEN THOUGH FILE PROTECTIONS FOR THE FILE SAY ALL PRIVILEGES TO GROUP USERS.) gid'S FALL IN THE RANGE 0-655535 WITH gid 1 BEING THE DEFAULT. aLL gid'S BETWEEN 0-99 ARE RESERVED. v. tHE iNFORMATION FIELD tHIS FIELD USUALLY HOLDS THE ACCOUNT OWNER'S NAME THOUGH IT CAN BE USED FOR ANYTHING ACTUALLY. i HAVE SEEN IT USED TO DESCRIBE THE ACCOUNT FUNCTION (SEE THE SAMPLE /ETC/PASSWD FILE ON THE ENTRY FOR LOGIN NAME "WHO"), AND ALSO TO HOLD PEOPLE'S PHONE EXTENSION, ETC.. vi. tHE hOME dIRECTORY fIELD tHIS FIELD SHOULD HAVE THE FULL PATHNAME TO YOUR HOME DIRECTORY. oN MANY unix SYSTEMS IT IS USUALLY IN THE FORMAT OF /USR/*LOGINNAME! (sEE THE ENTRY FOR LOGIN NAME "JSMITH"). nOT NECESSARILY YOUR permanent HOME DIRECTORY, ONE CAN CHANGE IT BY REASSIGNING AN ALTERNATE PATH TO THE SYSTEM VARIABLE $home (ON sYS v). vii. tHE pROGRAM fIELD uSUALLY THIS FIELD HOLDS THE STARTUP PROGRAM TO EXECUTE ONCE THE LOGIN PROCEDURE HAS BEEN COMPLETED. iF LEFT BLANK THEN THE DEFAULT STARTUP PROGRAM WILL BE THE SHELL ASSIGNED TO THE uNIX SYSTEM. iN THE OUR EXAMPLE /ETC/PASSWD FILE, THE ENTRY FOR LOGIN NAME WHO, WILL EXECUTE THE WHO COMMAND IN /BIN/WHO ONCE YOU LOG IN. hOWEVER, AFTER THE COMMAND FINISHES EXECUTING, IT WILL EXIT THE SYSTEM AS THERE IS NO PASSWORD ON THE ACCOUNT, THERE IS NO WAY TO STAY LOGGED IN. oN THE INFO ACCOUNT HOWEVER, YOU WILL REMAIN LOGIN UNTIL YOU TYPE EXIT OR LOGOUT OR ctrl-d AS THE PROGRAM RUNNING THERE IS A SHELL. tHOUGH NOT A FULL bOURNE SHELL OR c-SHELL, THE RESTRICTED SHELL (RSH) DOES ALLOW TO YOU PLAY AROUND A LITTLE. wELL, THAT ABOUT DOES IT FOR WHAT i WANT TO COVER IN pART i. lOOK FOR pART ii COMING OUT REAL SOON. i WILL BE GOING INTO DETAILS WHAT TO DO ONCE ONLINE WITH AN ACCOUNT AND HOW TO GO ABOUT GETTING AN ACCOUNT. tHIS FILE IS FOR INFORMATIONAL PURPOSES ONLY. ------------------------------------------------------------------------------ bROUGHT TO YOU BY: tHE aPPLE bANDIT 10-89 Text-Files 2: