Topic 713: Basic BSD System Administration

This topic focuses on managing user accounts and groups, automating tasks with cron and periodic scripts, maintaining system time, handling system logging, basics of Mail Transfer Agents (MTAs), printing, and managing user sessions.

713.1: Manage User Accounts and Groups

• FreeBSD:

  pw adduser bob -m -s /bin/sh
  passwd bob
  rmuser bob

• OpenBSD/NetBSD:

  useradd -m -s /bin/ksh alice
  passwd alice
  userinfo alice
  userdel alice

• Check user info:

  id alice

• Manage groups:
  • Typically by editing /etc/group or using commands like usermod.
  • Example:

    usermod -G newgroup alice

• vipw: Safely edits /etc/passwd (and /etc/shadow on some systems).
• chpass: Changes password configurations for a user account.
• chfn: Change finger information.
• /usr/share/skel: Represents the new user's home layout.

713.2: Automate System Administration Tasks by Scheduling Jobs

• Edit user crontab:

  crontab -e

• Example (run backup.sh at 3:15 AM daily):

  15 3 * * * /home/user/backup.sh

• List user crontab:

  crontab -l

• Cron allow/deny:
  • /var/cron/allow
  • /var/cron/deny

Periodic Scripts

• FreeBSD:

  periodic daily
  periodic weekly
  periodic monthly
  
  /etc/defaults/periodic.conf

• NetBSD: /etc/daily.conf, /etc/weekly.conf, /etc/monthly.conf
• OpenBSD: /etc/daily, /etc/weekly, /etc/monthly

713.3: Maintain System Time

• Check current time:

  date

• Set system time (e.g., 2025-01-27 12:00):

  date 202501271200

• NTP:
  • FreeBSD/NetBSD:

    ntpd -c /etc/ntp.conf
    ntpq -p

  • OpenBSD:

    ntpd -f /etc/ntpd.conf

713.4: System Logging

• Common log files under /var/log (e.g., /var/log/messages).
• Check logs:

  tail -f /var/log/messages

• Rotate logs:
  • newsyslog
  • Configure in /etc/newsyslog.conf

713.5: Mail Transfer Agents (MTA) Basics

• Sendmail:

  mailq
  sendmail -q

• Postfix:

  mailq
  postqueue -f

• OpenSMTPD (OpenBSD):

  smtpctl show queue
  smtpctl flush queue

• Aliases in /etc/mail/aliases, then:

  newaliases

• Relay configuration: Depends on MTA.

713.6: Manage Printing and Print Jobs

• Common BSD printing commands:

  lpc   # manage printer daemons and queues
  lpq   # list jobs
  lprm  # remove jobs

• Configuration in /etc/printcap.

713.7: Manage User Sessions

• Show who's logged in:

  w
  who
  users

• History of logins:

  last

• FreeBSD/NetBSD:

  lastlogin

• Log file: /var/log/lastlog