Transcript Setting Up TCP/IP Services

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
Need entry in /etc/passwd
Need password in
/etc/shadow
Need home directory
/home/[username]
Correct Permissions
$ man adduser
$ adduser <username>
$ man passwd
$ passwd <username>
Gui Alternative:
redhat-config-users
Runs on receiving a connection
man xinted
Start with:
chkconfig krb5-telnet on
Stop with:
chkconfig krb5-telnet off
Read manual page:
man telnetd
Set up accounts using:
adduser
Change account shell:
chsh <username>
(Tip: man ssh, chkconfig sshd on/off)
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ftp server
httpd server (apache)
ssh server
…
redhat-config-network-gui
Searching:
yum search [string]
Installing:
yum install [package]
Staying up to date:
yum update
Lots more!:
man yum
man yum.conf
Check logs:
/var/log/*
Monitor network activity:
tcpdump
Monitor processes:
ps
top
Move between accounts:
/bin/su – [username]
Permissions and ownership:
chmod <mode> <filename>
chgrp <group> <filename>
chown <user> <filename>
Manual pages:
man <command>
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!
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
Encryption
Access Permissions
Who/what do you trust?
Network Infrastructure
Use secure Protocols
Insecure
Secure
telnet
ftp
imap
http
ssh
scp
imaps
https
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File/directory permissions
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Firewalls
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DHCP?
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IP Addresses?
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Where does your data go?
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Switches? Hubs? Which route?
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Wi-fi