ISRL Laptop Connections

A frequently asked question late has been 'I have my own laptop--can I connect it to the network here in the ISRL and how do I do this?'

There are essentially four steps to getting the laptop on the network

  1. Determine the MAC or hardware address of the ethernet card in the laptop.
  2. Get this number to isrl-support
  3. A member of the admin team will update the DHCP server so that the MAC address will be assigned a network number when it connect to the ISRL network.
  4. The laptop runs some sort of DHCP client.

Determining the MAC or hardware address of your ethernet card

To allow the laptop access to the ISRL network (and therefore to the UIUCNet at large), we need to know the MAC address of the card. This is a twelve digit string consisting of digits (0-9) and a set of letters (A-F). Sometimes this is written on the network card itself, sometimes not.

If the number is written on the card, copy it down and proceed to step two. Otherwise, select your OS from the sections below.

Unix (Linux/Solaris)

If the number is not written down on the card, then you can obtain the MAC address from the (Unix/Linux) operating system using ifconfig:

    $ /sbin/ifconfig eth0

    eth0  Link encap:Ethernet  HWaddr 13:E7:7D:72:31:C9  
          inet addr:192.168.2.18  Bcast:192.168.2.255  Mask:255.255.255.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:344547 errors:0 dropped:0 overruns:0 frame:0
          TX packets:646837 errors:0 dropped:0 overruns:0 carrier:0
          collisions:358 txqueuelen:100
          Interrupt:10 Base address:0xe800

In this case, the MAC address is the string "13:E7:7D:72:31:C9".

Windows 2000 system

On a Win2k system, launch a command window by running "cmd" and then in the cmd window use the "ipconfig /all" command and look at the output. The relevant part should look something like this:

1 Ethernet adapter :

    Description . . . . . . . . : SMC 91C94 Ethernet Adapter
    Physical Address. . . . . . : 00-E0-29-1A-F4-24
    DHCP Enabled. . . . . . . . : Yes
    IP Address. . . . . . . . . : 192.168.1.101
    Subnet Mask . . . . . . . . : 255.255.255.0
    Default Gateway . . . . . . : 192.168.1.1
    DHCP Server . . . . . . . . : 192.168.1.1
    Primary WINS Server . . . . :
    Secondary WINS Server . . . :
    Lease Obtained. . . . . . . : 09 03 02 9:15:53 PM
    Lease Expires . . . . . . . : 09 04 02 9:15:53 PM

The "Physical Address" is what is needed - be sure to get the physical address for the actual network adapter card you have connected to ethernet - if you have a dialup connection there may be two "Physical Address" entries; the dialup one says "PPP".

In the above output, the MAC address is "00-E0-29-1A-F4-24"

Older Win95/98 systems

The command to run is winipcfg which will launch a configuration window. In this configuration window, ensure that you select the ethernet card from the dropdown box (and not the modem). Look for the hardware address or the adapter address. If the address that you find is '44-45-53-54-00-00', then you have the wrong device. Make sure that you have selected the ethernet card.

Get the MAC address to isrl-support

Send a request to isrl-support stating that you want to get your laptop MAC address added to the DHCP server's list of known machines. This link [isrl-support@isrl.uiuc.edu] has a partially composed mail to send to isrl-support.

Adding the address to the DHCP server

This is something that the technical staff have to do, so wait for a confirmation email. In the meantime, however, you should proceed to the next step.

Set up a DHCP client on your laptop

While you are waiting for the DHCP server to be updated, you should ensure that you are running a DHCP client on your laptop (DHCP is a technology that handles automatic assignment of network (IP) addresses.)

On a Linux machine, you should run something like dhcpcd or pump. It's that simple.

On many Windows machines you set up your laptop for DHCP something like as follows, assuming the laptop has a network card that is already in and configured for some network operation. If your network card connection has never been configured with TCP/IP, this has to be done first, and it's beyond the scope of this document.

To set up DHCP, first go to Control Panel->Network. Then select the TCP/IP connection to your network adapter by clicking once. Next, click on "Properties" and select the button for "Obtain and IP Address Automatically." OK all the windows to close them and you should be set---reboot the computer if necessary.

Concluding remarks

At this point you should be able to connect to resources on the network. By using the ISRL network resources, you are bound by the rules governing the access to UIUCNet resources. To read more, take a look at The Interim Policy on Appropriate Use of Computers and Network Systems at UIUC.

Thanks to Les Gasser for his contributions to this document


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