Usefull configuration files

Shell
bash file configuration file: /etc/bashrc

System
Globe environment variable and startup program: /etc/profile

Connection tracking: /proc/net/ip_conntrack

Iptable configuration file: /etc/sysconfig/iptable

Log system configuration file: /etc/syslog.conf

Network interface configuration file: /etc/sysconfig/network-script/ifcfg-eth*

• TYPE= Ethernet or Token Ring
• USERCTL=no or yes whether allow normal user active or inactive this NIC
• IPV6INIT=no or yes whether can configure Ip version 6 address with this NIC
• PEERDNS=yes or no whether get DNS info from DHCP server
• BOOTPROTO=static, none or DHCP

Port for each service: /etc/services

How to change RHEL IP Adress

1. Change in the Graphical console
2. Change in the command line GUI
   system-config-network-tui
   
3. Change the configuration file.
   Editing configuration files which stored in /etc/sysconfig/network-scripts/ directory. Those file separate by network interface name as "ifcfg-eth*".

# Intel Corporation 82573E Gigabit Ethernet Controller (Copper)
DEVICE=eth0
BOOTPROTO=static
DHCPCLASS=
HWADDR=00:30:48:56:A6:2E
IPADDR=10.10.29.66
NETMASK=255.255.255.192
ONBOOT=yes



   Save and close the file. Define default gateway (router IP) and hostname in /etc/sysconfig//network file:
   # vi /etc/sysconfig/network
   Append/modify configuration as follows:
   NETWORKING=yes
HOSTNAME=www1.nixcraft.in
GATEWAY=10.10.29.65


   Save and close the file. Restart networking:
   # /etc/init.d/network restart

   Make sure you have correct DNS server defined in /etc/resolv.conf file:
   # vi /etc/resolv.conf
   Setup DNS Server as follows:
   nameserver 10.0.80.11
nameserver 10.0.80.12
nameserver 202.67.222.222

   
   

Linux directory structure

• Home Directories: /root,/home/username
• User Executables: /bin, /usr/bin, /usr/local/bin
• System Executables: /sbin, /usr/sbin, /usr/local/sbin
• Other Mountpoints: /media, /mnt
• Configuration: /etc
• Temporary Files: /tmp
• Kernels and Bootloader: /boot
• Server Data: /var, /srv
• System Information: /proc, /sys
• Shared Libraries: /lib, /usr/lib, /usr/local/lib
• Documents of most installed package: /usr/share/doc
• New user template files: /etc/skel (all the files of folders under this directory will copy to /home/new user/* by useradd command)