1. Unix Linux Administration I
Week 5

2. Network Configuration
Basic networking
Routing and Subnetting
Netmsks vs CIDR
Ethernet card numbering (ethX and ethX:Y)
Current Server Configurations (public, private)
Interfaces file (and redhat equiv.)
Address, netmask, network, broadcast, gateway
Centos - /etc/sysconfig/networking-scripts
Debina - /etc/network/interfaces
Subnetting
Ip -> binary, netmask – binary, logical AND to get range
Hosts file - /etc/hosts
Override/statically set host -> ip entries
Troubleshooting?
Hostname configuration/meaning (fqdn, long, short)
Nsswitch.conf - configurable sources for information
getent

3. IPTables Network Ports Input, Forward, Output, default actions
(udp, tcp)
Input, Forward, Output, default actions
-p flag (protocol)
-s flag (source)
-i flag (interface)
-d flag (destination
DROP, ACCEPT, QUEUE, RETURN
NAT/IPMASQ
Prerouting, Postrouting, Output
Port forwarding

4. Startup scripts RunLevels /etc/init.d/* /etc/rc*.d/
0 – shudown
1 – single user mode
2 – multi user mode (no GUI) – default Debian
3 – multiuser mode (no GUI) – default for Redhat
4 – multiuser mode (no GUI) - typically unused
5 – multiuser mode (with GUI) – default for debian/redhat with GUI installed
6 - Reboot
/etc/init.d/*
Start and stop scripts
/etc/rc*.d/
Runlevels
Update-rc.d vs chkconfig
/etc/default # Default parameters for programs
/etc/alternatives # Default commands (more debian than redhat)
/etc/rc.d/* # Stores the RunLevel folders