1. A short two-part talk introducing: Basic Linux/Unix system administration (CentOS/RHEL5) General Computer/Network security … for the G53SEC module. Nick Reynolds. CentOS 5

2. Need entry in /etc/passwd Need password in /etc/shadow Need home directory /home/[username] Correct Permissions $ man adduser $ adduser $ man passwd $ passwd Gui Alternative: redhat-config-users

3. Runs on receiving a connection man xinted Start with: chkconfig krb5-telnet on Stop with: chkconfig krb5-telnet off

4. Read manual page: man telnetd Set up accounts using: adduser Change account shell: chsh (Tip: man ssh, chkconfig sshd on/off)

5.  ftp server  httpd server (apache)  ssh server  …

6. redhat-config-network-gui

7. Searching: yum search [string] Installing: yum install [package] Staying up to date: yum update Lots more!: man yum man yum.conf

8. Check logs: /var/log/* Monitor network activity: tcpdump Monitor processes: ps top

9. Move between accounts: /bin/su – [username] Permissions and ownership: chmod chgrp chown Manual pages: man

10. CentOS5 (RedHat EE) Documentation http://netlab-gw.cs.nott.ac.uk/centos/5/docs/ http://ftp.cs.nott.ac.uk/centos/5/docs/ Linux Documentation Project http://newton.ex.ac.uk/LDP/ Search Engines!

11. Many ways to achieve the same result. Experiment within a user account. Don’t make to many changes in one go. Stay up to date (yum update) Advanced methods to configure servers: man pam

12. Encryption Access Permissions Who/what do you trust? Network Infrastructure

14. Use secure Protocols InsecureSecure telnetssh ftpscp imapimaps httphttps

16.  File/directory permissions  Firewalls

18.  DHCP?  IP Addresses?

20.  Where does your data go?  Switches? Hubs? Which route?  Wi-fi