9. Internet

The previous sections show you what you have to do to get a working Internet connection. Here is some background discussion just in case you need more than just the answers.

The networking programs are on the Slackware-N disk set, and elsewhere on the CD's. Your distribution has probably already loaded them, but you need to configure them to your site.

(Slackware) /var/adm/setup/setup.netconfig, may help you establish an initial configuration, (or destroy any existing configuration). Other utilties like linuxconf, may or may not help.

You have to do several things to get networking up. This may include rebuilding the kernel, configuring modules and making the serial port work at high speed. To make it easier to understand, I have split those into seperate sections. You should read them (and keep them in mind) when configuring Internet.

Internet is just a special case of TCP/IP in general. If you wanted to, you could create your own private Internet, and in fact many Internet providers use Linux to implement the real thing!

To get Internet working, simply put the correct values into the correct files and it will work. Usually.

9.1 Documentation
9.2 ISP Account Information
9.3 ISP Toolkit
9.4 Overview




ISP Account Information

There are different types of account.

Static IP Address

I have an account that gives me a static IP address, and hostname. I recommend that you do the same, though some people might find it easier to get a more spoon-fed service which may be more reliable.

This means that I rent the "trix.dircon.c.o.uk" name and it's IP address from dircon. The IP address is valid 24x7, but if I'm not currently dialed_in, you get a HostNotReachable message.

When I am connected, the configuration is exactly the same as a leased line, except the machine is only there for a short while.

My machine can use or provide any TCP/IP service that I can get configured correctly, so I run my own web server (but the pages are the same as sunsite ;-), ftp server, SMB server, NFS server. You Windows users could even read Raven over a networked disk, from my SMB server (Workgroup HARROW) - though noone does, so I'll probably remove the config line.

It isn't easy for me to test these things with one machine, but you as a business can run (almost) anything over the modem that you can run over the ethernet.

I can create any number of email accounts on my machine, such as postmaster@ webmaster@ raven@ gps@ LochNessMonster@, all under my own control. Dircon simply route <anthing>@trix.dircon.co.uk to me.

When I'm not connected, dircon provide a backup machine, and advertise it in my MX-DNS records, to accept email on my behalf. It holds upto N-days and upto N-MB of email data.

As well as email spooling, dircon provide a local news machine, and allow me to post some WEB pages on their 24x7 server. Other ISP's do similarly.

The only limitations on my account are that I must comply with their acceptable use policies (no porn, racism, etc) and that I must be a small business, or single family. ie this is a personal account, not a mega-down-stream feed.

Dynamic IP Address

Dynamic, means that each time you connect, you get a different IP address.

The address you get is still a valid global Internet address, so you can have services like WEB-server running, but because it changes, the address is a bit harder for others to find.

If you are not connected, the lookup fails, if you are connected they will probably cache the lookup, so if you disconnect and reconnect with a different address ... all sorts of problems.

That will only effect you if you are providing a TCP service, or if the modem drops half way through a connection (with a static address, and a bit of luck you can reconnect before TCP/IP notices, or gives host un-reachable). There will just be a long delay, and you can prompt the retries by making another TCP connection, eg telnet).

Dynamic addresses mean a bit more work for the provider (and you), essentially it works by them giving each of their 100 modems a static address. You get the address of the modem you connect to. However, with PPP and a bit of configuration, universities should be using static addresses for each student (even if in the private range, via a masquerading proxy).

Email Account

Here you are not directly connected to the Internet. All the services that you use, are accessed through a single host at the providers site (or possibly a few).

Now you definately have only one email account name, something like YourName@dircon.net

It may well be that the connection between your machine, and the provider's LAN uses TCP/IP, probably an address in the PRIVATE range. That address may itself be static or dynamic, and give access to a number of hosts. An internet, but not The Internet.

Shell Account

A shell account, is like an email account, but you have a single login to the providers machhine. They may even give you shell access to store your own programs, compile them, run them (etc). A security nightmare, and a facility straight-jacket.

UUCP feed

This is a specific type of connection, often used by people who want a bulk-email and bulk-news feed. Traditionally expensive.

Account Information

So given that you have purchased (renting) a static IP address and hostname, your provider will provide you with the information you need to connect. If they offer auto PPP configuration, use it.

You will be collecting mail by SMTP, but popmail is also an option.

Your ISP will tell you:

You MUST substitute your values into these scripts. Using my ISP's nameserver for your requests won't make me popular, and may or may not work, depending on whether the ISP checks who made the call, and whether it advertises the outside to the outside.

The number of things that you have to configure is probably more than you remember to do. Sometimes each application requires it's own (improved) config setting, sometimes they share configs.


ISP Toolkit

As well as your IP address, your provider may be providing instructions on how to use it. eg:



Many people will be connecting their workstation to the LAN, using an ethernet card. If you only have a null-modem RS232 cable, or a PLIP cable, you will need to interpret the text relating to ethernet, but it's much the same.

You will also be connecting your Linux workstation to the Internet, using a modem. You can be connected to both the LAN and the Internet at the same time, but Issue-3 doesn't go as far as bridging them, eg with a proxy gateway.

Normally, establishing the Internet PPP or SLIP link, requires root login permissions. You will configure an suid script, and /etc/group to allow a list of "plain" users to bring the link up and down.

This text will help you understand what the manuals are talking about. When you need details that isn't there, you will already be familiar with topics discussed in the README's and FAQ's, and should find things sooner.

The HOWTO's describe dialing IN as well as out. Don't get frightened by that! Internal modems are the same as external modems, but appears as an additional UART chip on the machine.

Your ISP will allocate you a static IP address, and will advertise that address on their nameservers, so that others will find you. This helps with email, but also with direct access to services on your machine. IE if you are currently on-line and dialed in, others can call you for ftp, web pages, telnet-login and other services.

My ISP allows me to connect using either PPP or SLIP. When I connect, after login and password, they present an additional question "Protocol?". Your CHAT and DIP scripts will be different.