13. Setting up basic networking

13.1 Installing Netkit-base

• Unpack the Netkit-base archive
• Configure the package by running configure
• Compile the package by running make
• Install the package by running make install
• Copy the following files from the etc.sample directory to the /etc/ directory: services protocols

13.2 Installing Net-tools

• Unpack the Net-tools archive
• Compile the package by running make
• Install the package by running make install

Creating the /etc/init.d/localnet bootscript

• Create a new file /etc/init.d/localnet containing the following:

#!/bin/sh
# Begin /etc/init.d/localnet
 
check_status()
{
  if [ $? = 0 ]
  then
    echo "OK"
  else
    echo "FAILED"
  fi
}
 
echo -n "Setting up loopback device..."
/sbin/ifconfig lo 127.0.0.1
check_status
 
echo -n "Setting up hostname..."
/bin/hostname --file /etc/hostname
check_status
 
# End /etc/init.d/localnet

Setting up permissions and symlink

• Set the proper permissions by running chmod 755 /etc/init.d/localnet
• Create the proper symlinks by running cd /etc/rcS.d; ln -s ../init.d/network S03localnet

Creating the /etc/hostname file

Create a new file /etc/hostname and put the hostname in it. This is not the FQDN (Fully Qualified Domain Name). This is the name you wish to call your computer in a network.

Creating the /etc/hosts file

If you want to configure a network card, you have to decide on the IP-address, FQDN and possible aliases for use in the /etc/hosts file. An example is:

<myip> myhost.mydomain.org somealiases

Make sure the IP-address is in the private network IP-address range. Valid ranges are:

Class Networks
A     10.0.0.0
B     172.16.0.0 through 172.31.0.0
C     192.168.0.0 through 192.168.255.0

A valid IP address could be 192.168.1.1. A valid FQDN for this IP could be me.lfs.org

If you're not going to use a network card, you still need to come up with a FQDN. This is necessary for programs like Sendmail to operate correctly (in fact; Sendmail won't run when it can't determine the FQDN).

Here's the /etc/hosts file if you don't configure a network card:

# Begin /etc/hosts (no network card version)
127.0.0.1 me.lfs.org <contents of /etc/hostname> localhost
# End /etc/hosts (no network card version)

Here's the /etc/hosts file if you do configure a network card:

# Begin /etc/hosts (network card version)
127.0.0.1 localhost
192.168.1.1 me.lfs.org <contents of /etc/hostname>
# End /etc/hosts (network card version)

Of course, change the 192.168.1.1 and me.lfs.org to your own liking (or requirements if you are assigned an IP-address by a network/system administrator and you plan on connecting this machine to that network).

Creating the /etc/init.d/ethnet file

This sub section only applies if you are going to configure a network card. If not, skip this sub section and read on.

Create a new file /etc/init.d/ethnet containing the following:

#!/bin/sh
# Begin /etc/init.d/ethnet
 
check_status()
{
  if [ $? = 0 ]
  then
    echo "OK"
  else
    echo "FAILED"
  fi
}
 
/sbin/ifconfig eth0 <ipaddress>
check_status
 
# End /etc/init.d/ethnet

Setting up permissions and symlink for /etc/init.d/ethnet

• Set the proper permissions by running chmod 755 ethnet
• Create the proper symlinks by running cd ../rc2.d; ln -s ../init.d/ethnet S10ethnet

Testing the network setup

• Start the just created localnet script by running /etc/init.d/localnet
• Start the just created ethnet script if you have one by running /etc/init.d/ethnet
• Test if /etc/hosts is properly setup by running:

ping <your FQDN>
ping <what you choose for hostname>
ping localhost
ping 127.0.0.1
ping 192.168.1.1 (only when you configured your network card)

All these five ping command's should work without failures. If so, the basic network is working.