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To access the contents, click the chapter and section titles.
Complete Idiot's Guide to Linux
(Publisher: Macmillan Computer Publishing)
Author(s): Manuel Ricart
ISBN: 078971826x
Publication Date: 12/22/98
This is where you manage your current accounts and add new ones. Other features of this window include:
- Accounts tabShows all currently defined entries.
- Device tabClick to set up the device where your modem is connected.
- Modem tabClick to set special modem options.
- PPP tabClick to set some options for kppp.
- About tabClick to learn more about kppp.
- List of entriesSelect an entry and click Edit to edit it.
- Edit buttonClick to edit the currently selected entry.
- New buttonClick to define a new account.
- Copy buttonClick to duplicate an existing entry.
- Delete buttonClick to delete the selected entry.
- Phone Costs, Reset Costs button, and View Logs buttonAllow you to keep track of the time you are spending online. Useful for keeping track of your costs if your connection is billed by the minute.
When you click the New button, the New Account window appears, as shown in the following figure.
 The Dialup Configuration offers several panels to set the dialup information, IP address for your machine, and DNS server settings, among other things.
Adding a New Dialup Configuration
When you create an account, there are several things that you need to define. First youll need to configure your dialup settings, by using the Dial tab in the New Account window. This window requires you to provide a name for your ISP. This name is displayed by the Connect to menu. The other information you need to provide is the phone number to your ISPs modem banks. The Authentication menu selects how to connect to your ISP. If your ISP supports connections from Windows 95/98/NT, chances are that the PAP authentication is all you need. Other authentication methods are available if that one doesnt work, but they require that you create a small chat script. Ill show you how to create one later in the section titled Using a Login Script.
Configuring the IP Settings
Next youll have to define your IP address settings for the connection. Special network devices, called routers, are responsible for delivering packets between networks. Most ISPs assign IPs dynamically. When your computer connects to the ISP, it will be assigned an IP address that it will use throughout the duration of your session. Next time you connect, youll get a different number.
The PPP protocol can handle dynamically assigned IP addresses. The IP tab in the panel allows you specify the settings kppp should use, as you can see in the next figure.
Techno Talk: So What Is All This IP Stuff, Anyway?
The Internet is a network of networks held together by a few protocols that define how information is routed and sent between computers. Information sent between computers is broken up into many small pieces (called packets or datagrams).
Packets are similar to mail you send through a post office. Each packet holds several pieces of information, including the address for the computer where it should be delivered, the address of the computer sending the message and the actual information, text, bits for an image, and so on.
When you hook up to the Internet, you become part of this large network. Your computer is identified uniquely (well, that is, if you are not behind a firewall), allowing you and other computers on the Net to talk to one another.
When you hear people talking about an IP, they are really talking about an IP address. In reality, IP stands for Internet Protocol, and its function is to wrap other protocols so that they can be delivered to the right computer using a network. The IP provides an envelope with the necessary information to get the packets from one computer to another. Therefore, for you to network on the Internet, you need to have some way to uniquely identify your computer. Thats why you need an IP address.
Although IP provides information to send the data, it does not tell how the computers exchange this information. Other protocols that ride on top of IP do this. Data between computers on the Internet is typically transmitted using one of two major protocols: TCP or UDP.
 The IP tab of the New Account window.
Techno Talk: OK, Smarty-pants, So Whats TCP, UDP, and PPP?
TCP stands for Transmission Control Protocol. TCP uses IP to pass information packets between computers. It is a connection protocol; computers connect to each other before sending information. The main advantage is that this connection protocol guarantees that packets you send are delivered and that the packets are put back together in the right order by the receiving computer. This is needed because information is broken into many small packets. Each packet has a serial number indicating its position on the data stream.
UDP stands for User Datagram Protocol. UDP is a connection-less protocol. It is a minimal protocol, and it is very fast. The only problem is that UDP doesnt make any guarantees that the data will get to its destination. Typically, UDP is used for sending very short messages between computers in which the time costs of establishing a TCP connection far exceed the needs. Most information sent via UDP is sent using just a single packet.
PPP is a mechanism for doing IP networking over serial lines (your modem). There other serial lines protocols, such as SLIP (Serial Line Internet Protocol), but PPP has established dominance partly because of its flexibility in not requiring a fixed IP address. PPP connections typically negotiate the IP address when you connect to your ISP.
Check the Dynamic IP Address button if your ISP assigns IPs dynamically. If you have a dedicated IP address (static address), enter that address and the subnet mask in the Static IP Address section. If you want kppp to temporarily set the domain and host name of your computer to the one matching the address assigned by your ISP, click Auto-configure hostname from this IP.
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