Ask SIPB - August 24, 2003

Want to get network in your dorm? Interested in setting up a server? In this column, part 2 of 6 in our introductory orientation columns, we cover residential computing and getting connected to the network.

Should I set up my computer now?

As mentioned in Friday's column, if you are an undergrad, in general, it is best if you do not set up your personal computer right away. Unless you live in McCormick, which has forced room squatting, you will almost certainly be moving to either another dorm, or at least another room.

If you need to use a computer, there are always the Athena clusters easily accessible all over campus. Once you move to your room for the fall term on Thursday, feel free go ahead and set up your computer. But in the meantime, take advantage of Orientation, and have a great time!

When you do finally set up your computer, if it is running any version of Windows, please IMMEDIATELY apply the appropriate patches. Because of the recent exploited RPC vulnerability, unpatched Windows system may be compromised very quickly, before they have a chance to get patched. To work around this, you should block all incoming TCP connections before connecting your computer to the network and running Windows Update. The directions at detail this process.

If you do not follow these instructions, your computer will likely quickly get compromised, and Network Security will turn off your network drop and/or disabled your DHCP access. In such cases, you must reformat your hard drive and reinstall the operating system, which can certainly be inconvenient. For more information, see

Running Windows Update is always a good idea, though it is especially important now because of the recently discovered RPC vulnerability. Also ensure that you have a non-trivial Administrator password, as your system can otherwise be remotely broken into. To learn more about what makes a non-trivial password, visit

What is DHCP, and how do I configure my computer to use it?

DHCP is the Dynamic Host Configuration Protocol, which allows your computer to automatically obtain an IP address and associated information such as DNS entries. If you are not running a web server, and do not need a static IP address for any other reason, we recommend using DHCP as it is the most flexible and easy to set up. Most computers are set to use DHCP by default.

To use DHCP to connect to the network, configure your computer to use DHCP by following the instructions at These are typically the default settings, so if you have not changed anything, you likely need not do anything. Then, simply open up a web browser, and complete the registration that appears automatically.

What are the two types of DHCP registration at MIT?

MIT has two different types of DHCP registration. The first, and most common, is dyn-o-reg. This is what comes up when you bring up a web browser for the first time on an unregistered machine. The second type is called dhreg. This is generally only useful for laptops, as it associates your hostname with your network card's MAC address so that you can configure your computer to obtain your static IP address via DHCP when you are on your home subnet, typically your dorm, and to obtain a random address while you are elsewhere.

If you have a laptop that has a static IP address, and you would like to register it for the dhreg type of DHCP so that you do not have to change its settings when you leave your home subnet, visit the registration page at from the computer you wish to register. The computer should be on your home subnet at this time, and using its static IP address. Instructions for this are also included in the wireless configuration question below.

What is a static IP address good for?

A static IP address is useful if you wish to set up your own server, like a web server, as it means your machine always has the same IP address, instead of getting a new one each time you reboot. Typical servers students run include web servers and ftp servers. In addition, if you configure your machine properly, you can also set up remote access through SSH, VNC, or a similar protocol. While these things are still all possible without a static IP address, you will not have a consistent hostname or IP address you can use to access your machine.

To connect your computer to the network with a static IP address, follow the instructions you receive when you request the IP address. You can request the address either at a "Getting Connected" meeting (see below), or through the RCC web page at

How can I use the wireless network at MIT?

Most non-residential MIT Buildings now have wireless network access. You can find a list of wireless-enabled locations at Furthermore, wireless is gradually being deployed in many dorms. Baker House, Senior House, Sidney-Pacific, Simmons, and The Warehouse all have official I/S-deployed wireless service, and Bexley and East Campus will have wireless service deployed during this school year. Other dorms may have wireless access points set up by residents, though these are not officially supported. Signing up for this service is easy, and detailed instructions are available at

If you're an MIT student, and have a static IP address, follow the instructions for faculty and staff members. If you don't have a static IP address, do the following: First, install your wireless Ethernet card: see MIT supported wireless cards information at Then in W20, N42, or your dorm, turn your laptop on, and open up a web browser to any website - you should be redirected to the registration website. If you have trouble, see the instructions at Read the MITnet rules of use, click on the Register button, enter your Athena username and password, and click register. After the confirmation message is displayed, reboot your machine, and within 15 minutes you should be able to use wireless ethernet in most parts of campus.

If you're a faculty or staff member, then you first need to get a static IP address for your laptop. Go to Then, configure your laptop's wired Ethernet card for network using the static IP address you receive and reboot. Open a web browser and go to to register for wired DHCP. After restarting your computer with DHCP enabled, register at Enter your hostname, and then the MAC address (aka Hardware address, ethernet address, Airport ID) of your wireless ethernet card. This is a set of 6 pairs of characters, often separated by colons or whitespace (e.g., "71:23:f7:0c:7f:b1" or "ee a0 13 d1 f8 0a"). The MAC address will be printed somewhere on your wireless card. If you have a Macintosh with built in wireless, you should go to the Airport Control Panel, and look for the "Airport ID". When entering the MAC address in, make sure that you only enter the alphanumeric characters, and that you enter the letters in lowercase. For example, the above two sample MAC addresses should be entered as 7123f70c7fb1 and eea013d1f80a. After you've entered these in, in about 15 minutes, you'll be able to use wireless ethernet in most parts of campus.

How can I find more information about a machine?

To get more information about a machine, including its IP address, aliases it has, and its owner, you can use type stella machinename at an Athena prompt. For example:
athena% stella news

Address:         Network:    SIPB            
Owner:    NONE                Use data:   11-aug-2003 07:58:12
Status:   Active (1)          Changed:    18-jun-1994 22:41:53

Vendor:   SUN                 Location:        W20-575A
Model:    ULTRA-60            Contact:         usenet
OS:       SOLARIS             Billing Contact: usenet
Opt:      0                   Account Number:  1639400

Adm cmt: 
Op cmt:  

Created  by smsuser on 24-nov-1993 13:07:13
Last mod by zacheiss.dbadmin@ATHENA.MIT.EDU at 24-nov-1999 01:09:43 with moira.
In the case of student machines, the owner and contact fields will also tell you who owns the machine.

Where can I get more help with networking and getting my computer configured properly?

Each dorm has student Residential Computer Consultants (RCCs) who can assist you with network problems. The RCCs can help you configure your computer's network settings, provide you with a network cable, assist with broken network drops, assign you a hostname and IP address, and help with other network-related problems. To submit a request, visit

In addition, the RCCs will be running "Getting Connected" meetings throughout orientation, in which you can learn more about these topics and more. The schedule for these meetings appears below:

Monday, 8/25, 10-11am, 4-370
Tuesday, 8/26, 10-11am, 1-190
Wednesday, 8/27, 10-11am, 1-190
Thursday, 8/28, 3-4pm, 4-370
Friday, 8/29, 3-4pm, 4-370

To ask us a question, send email to We'll try to answer you quickly, and we can address your question in our next column. You can also stop by our office in W20-557 or call us at x3-7788 if you need help. Copies of each column and pointers to additional information are posted on our website: