1. Unix System Administration Chapter 6 Adding New Users

2. Bob + Jane = Adding Users n Edit /etc/passwd (& /etc/shadow if necessary) n Set the password using passwd command n Create the user’s home directory n Copy config files (dot files) to the home directory n Setup any mail aliases

3. How Many Users Does It Take To Screw-Up Your System? n Add user to any secondary groups via /etc/group n Record account info (paper) n Enter user into site-wide database (e.g. LDAP) n Configure disk quota n verify account is setup correctly

4. Can’t Unix People Spell? n /etc/passwd format –username (must be uniq) –encrypted password (“x” if shadow used) –userid (does not need to be uniq, 0-65535) –groupid (primary group) –gecos (comment or real name field) –home directory location –login shell (empty = /bin/sh)

5. Everybody Has a Better Mousetrap n Edit the password file using vipw or just vi n Other utilities to ease account creation and management –Most OS’s have a utility to add users –useradd/usermod/userdel (Linux, Solaris, …) –admintool (Solaris) –smit or smitty (AIX) –linuxconf (Linux)

6. Size Does Matter n 64 (1 char password) n 4,096 (2 char password) n 262,144 (3 char password) n 16,777,216 (4 char password) n 1,073,741,824 (5 char password) n 68,719,476,736 (6 char password) n 4,398,046,511,104 (7 char password) n 281,474,976,710,656 (8 char password)

7. So Long Sucker, Er, I Mean Alumni n Removing a user –backup all user info (below) first –remove entries in /etc/passwd and /etc/shadow –remove userid from /etc/group –remove any entries in /etc/aliases –remove mail spool file (INBOX) –remove home directory

8. I Have The Power n Setting quotas –edquota username –edquota -p protousername username n Disabling account (but not removing) –passwd -l username

9. Stop Your Web Browsing and Pay Attention! n Name a possible problem with reusing UIDs. n What/who is PAM? n How many characters are actually used in the password?