UA Library > Intranet Home This University of Arizona Library site is archived and is not maintained. UA Library > Intranet Home This University of Arizona Library site is archived and is not maintained.As Others See Us: What is your IP number? and why you should care!
What is an IP number? It's the unique address assigned to the device you are using to connect to the Internet. It's a combination of 4 numbers separated by periods. Each section of the IP number narrows down who you are:
128.196 is Arizona.EDU
128.196.228 is library.Arizona.EDU
128.196.228.6 is bandar-log.library.Arizona.EDU
"bandar-log.library.Arizona.EDU" is a domain name, basically a mnemonic that can be used to replace the IP number. There's a general correspondence between the parts of an IP number and the parts of the domain name, but it's not always exact. For example 128.196.228, 128.196.51, and 128.196.102 are all library.Arizona.EDU (this allows us to logically connect the Main and Science-Engineering Libraries).
Why should you care about your IP number? Because the most common way of determining whether you should be allowed access to Internet resources is based on your IP number! For example, our contract with most of the vendors of databases that the library buys lets us allow access from the U of A campus, which is Arizona.EDU (128.196). If you have an IP in this domain, you will be allowed to use the resource. If you don't, you will be blocked out. We also have to block access from specific machines on campus that allow free and uncontrolled access to anyone who connects to them (for example, the terminal servers at CCIT).
The type of connection you use will determine what IP number you are seen as having by the rest of the world:
Ethernet (10BaseT) line in the library: A specific IP number is assigned to your PC and used in all your communications software. Usually when the PC is installed LIST will ask you what you want to "name" your PC, and that name will get associated with that specific IP no.
Terminal server shell account (either in the library or via dial up from home): Your IP number is the IP number assigned to the terminal server.
SLIP or PPP account: either you have a unique IP number assigned to your account or an IP number is assigned to you "on the fly" when you dial in and log on. In either case, whether you will be part of Arizona.EDU depends on your Internet service provider (ISP). If you have an account with CCIT through the library or an individual account with UAConnect, you will be in Arizona.EDU. Otherwise you won't. If you have an account with StarNet or Compuserve or America Online, you're out of luck.
Also, Internet hosts will see you as coming from the IP number of the machine where you ran the software for the protocol you are using (telnet, FTP, gopher, World Wide Web, etc.). This usually pretty simple for ethernet, SLIP or PPP accounts, since you will usually run that software on your PC. The exception is for telnet connections. Telnet connects from your machine to the host you specify (call it host A). If you want to connect to a second host (host B) from there, you will have to run telnet again on host A to connect to host B. Host B will see you as coming from host A.
When you connect to a terminal server, you have to run telnet from the shell account. So the host you connect to will see you as coming from that terminal server. What happens with further connections depends on the protocol you use.
Let's look at some examples of this:
1. Let's say you dial 621-9600 from home (the terminal servers at CCIT) and then telnet to SABIO.
Home-------(dial up)-------Terminal server----(telnet)------(SABIO)
SABIO will see you as coming from the IP number of the terminal server. Access to subscription databases will be blocked (since the terminal servers don't require a campus account to login).
2. You dial 621-9600 from home (the terminal servers at CCIT) and then telnet to UAInfo. When you connect to UAInfo, a Web browser runs automatically and when you select a link to the UA Library, the browser connects to the library.
Home---(dial-up)---Terminal server---(telnet)----UAInfo----(WWW)----Library
The library's Web server will see you as coming from UAInfo, and access to subscription databases will be blocked (since UAinfo doesn't require a campus account to login).
3. You dial 621-9600 from home (the terminal servers at CCIT) and then telnet to Bird. You then telnet to SABIO.
Home----(dial up)----Terminal server---(telnet)----Bird---(telnet)-----SABIO
SABIO will see you as coming from Bird. Subscription databases will be available to you, since Bird requires a campus account to login.
4. You connect to your SLIP or PPP account, then run Netscape and connect to UAInfo. You click on the link from UAInfo to the SABIO WWW server. This is best illustrated in two steps. After you connect to UAInfo, the connection looks like:
Home-------(WWW)--------UAInfo SABIO
After you follow the link to SABIO, your connection looks like:
Home-------------(WWW)-----------------------SABIO
[UAInfo (no longer involved)]
SABIO sees the IP number assigned by your Internet service provider to your PC, and allows access to subscription databases based on that. This is the way client/server protocols like the World Wide Web work. When you change the server you are connecting to, a direct connection is made from your browser to the new server.
5. You connect to your SLIP or PPP account, then telnet to UAInfo, where Lynx (a Web browser) is run automatically. You then select a link to SABIO
Home------(telnet)------UAInfo-------(WWW)---------SABIO
SABIO does not allow access to subscription databases. It sees your connection as coming from UAInfo, because that was where your Web browser was run.