System Administration 2017/18 spring

The order of following commands depends on what you fix first.

1. Check if you have new hostname applied hostname
2. find unused IP address: nmap -sP 192.168.10.0/24
3. Test Default Gateway: ping 192.168.10.1
4. Test The Internet: ping 8.8.8.8
5. Check what server is used for resolving: cat /etc/resolv.conf
6. Check if any DNS can be reached (for example Google) and can resolve ut.ee dig @8.8.8.8 ut.ee
7. Check if your own DNS can resolve world wide addresses (here X is last octed of your own IP) and can resolve ut.ee dig @192.168.10.X ut.ee
8. Check if your own DNS can resolve your own domain dig @192.168.10.X ut_login.estNS
9. Check the Mail exchange host for your domain (here X is last octed of your own IP) dig @192.168.10.X utlogin.est MX
10. Check if the resolver can actually resolv nslookup www.google.com and nslookup utlogin.est
11. Check active Firewall rules with iptables -S or iptables -L -n
12. Check if your laptop/classroom machine can access your Virtual Server ping 192.168.10.X and ping mail.<yourdomain>.est if not add your Server IP as primary DNS in laptop (client).
13. check status of services postfix, dovecot and apache wit systemctl status postfix.service -l
14. Server can send e-mail locally using alpine and through Thunderbird
15. With lynx check if apache pages can be reached locally from server lynx https://www.<yourdomain>.est
16. Check if https://www.<yourdomain>.ykz can be reached from a client (your laptop)
17. Check if http://webmail.<yourdomain>.ykz will be routed to roundcube login page and HTTPS.
18. Check if you can log into roundcube and test sending e-mail to different user.
19. Check if new secure vhost exam.ut_login.est with userdir module serving only user tester with PHP
20. Commands named-checkconf, named-checkzone, postconf -n, doveconf -n and apachectl -S might help you too.
21. Common log files to check for errors:
    • /var/log/syslog
    • /var/log/mail.log
    • /var/log/bind9/
    • /var/log/dovecot/
    • /var/log/apache2/
    • /var/log/
22. More useful commands:
    • Checking in what file and at what line the value occurs (over multiple files):
      • grep -Hni <value> <file.*>
        • Here -H highlights file name
        • Here -n highlights line number
        • Here -i for case insensitive search
      • grep -Hni <value> <*.conf>
    • Checking in what file and at what line the value occurs (over all files in directory):
      • grep -RHni <value> <dir>
        • Here -R for recursive traverse over directory contents
    • Checking in what file and at what line the value occurs (over specific files in directory):
      • find <dir> -iname '.conf' -exec grep -Hni <value> {} \;
        • Here <dir> where to look for files
        • Here -iname '.conf' how to match file names
        • Here -exec <cmd> what to execute on each matched file
        • Here {} substituting the matched filenames into grep -Hni <value> <file> command
        • Here \; terminating the -exec closure of find command
    • Filtering not commented lines:
      • gerp -v '#' <file>