Linux / Unix DHCP Client Setup Guide

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Notes:

•  This document tries to be as generic as possible, but due to the variance of Linux and Unix distributions there may be discrepancies
  
   
•  This document will not try to explain network card driver installation due to the complexity. It is assumed the user has a basic understanding of the OS, has already installed the network card, and has the necessary kernel modules loaded or compiled in.

To use a computer running the Linux or Unix OS with ResNet, it will need to have an Ethernet adapter installed and a DHCP client installed and enabled. For detailed instructions on installing network card drivers or kernel modules, as well as configuring the network adapter card to use DHCP, we suggest reading the various applicable HOW-TO documents which can be found at The Linux Documentation Project for all versions of Linux, or at the Unix distribution's site.

 

 

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Step 1

 

From a shell type ifconfig. It will list all Ethernet adapters which are configured and up(turned on or enabled). There will almost always be an adapter listed as lo, for the loopback device. There may also be other adapters which are configured and running. If so, for each listed adapter perform ifconfig ADAPTER_NAME down. This will turn off all network functionality so settings may be changed. It will not be necessary to turn off the lo adapter







 

 

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Step 2

 

On Unix and Linux, it is necessary to start a DHCP client. Some of the most common clients are dhcpcd, pump, and dhclient. You can determine which client is installed on your computer by typing whereis clientname, such as "whereis dhcpcd". If a client is installed it will return the clientname followed by the directory it is installed in.

• To start dhcpcd type "dhcpcd -n -H eth0".
• To start pumpd type "pump -i eth0 -h hostname".
• To start dhclient type "dhclient fxp0".

 

 

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Step 3

 

Performing ifconfig -a with no options will show the interface's new settings and should list it's new IP address as assigned by DHCP. If it appears that the computer has gotten an IP address, you may wish to place the command you used in step 2 into a startup file such as rc.local so that the interface gets an IP address every time the computer is started. Otherwise you will have to type the command each time the computer restarts.

If the computer did not get a new and valid IP address, it may be necessary to change options used for the dhcp client. This is beyond the scope of this document and can be found in the man pages of the specific client.






 

 

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Step 4

 

Upon bringing up the interface, several routes should automatically have been added to the routing table, and a default gateway should be present. Check this by typing netstat -rn.You should see a default route listed, it will either say default or the destination will be 0.0.0.0 If the default route has not been added , check the troubleshooting guide under the Routes section.






 

 

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Step 5

 

The /etc/resolv.conf file contains information which is used to specify DNS server information. DNS is necessary to provide name to IP address mappings for the Internet. After bringing up the interface with DHCP, the file should contain information similar to the picture. You can check the contents of the file by typing cat /etc/resolv.conf. If the file contains information different from the picture, see the section under troubleshooting entitled DNS.






 

 

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Step 6

 

After registering your computer on ResNet, you can check that DNS is functioning properly and that the routes are configured correctly by typing host erau.edu. It should return the IP address of the erau.edu server as shown.If you've registered your computer and gotten an IP address, but you can't seem to browse the web, see the section under troubleshooting entitled DNS.








Once you have received an IP you will need to follow the directions in the ResNet Welcome Screen.
 

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Not working? Try Troubleshooting