Linux in the Real World
ISPs offer access to their networks to people they usually have never met. As such, you will need to keep a constant eye on the security aspects of your system. Start with a good introduction to network security, such as Cheswick and Bellovin's Firewalls and Internet Security, which served as my introduction to networking in general.
A good place to start is with a packet filter on the router connecting you to the Internet. A good packet filter and careful password management are two small steps that will put to rest 90% of your security concerns. The most important step you can take with Internet security is to understand it and to use the tools (like TCP wrapper and packet filters) at your disposal.
The above descriptions cover the high spots of all the issues which you will face in starting up an ISP business using Linux. It is doable; we at Cheney Communications and countless other ISPs are living proof of this.
You will have problems with your network. You should get used to that fact now. Fortunately, the good people on Usenet in comp.os.linux.networking (myself included) are always ready to help. The Linux Documentation Project is an invaluable resource when trouble arises. It is even more useful before trouble arises!
By now you should have a pretty good idea of what equipment you will need in order to start dishing out IP services. Are you going to offer limited Usenet and e-mail to a few businesses? An ISDN connection and a pair of 486DX-66s should do the trick. Are you starting up a full-service ISP for dial-up and leased-line services, with a full news feed and commercial web hosting? Three Pentiums (dedicated news server, dedicated PPP server, and a mail/WWW machine) and a router might be a good start.
You need to make sure that you have all of your ducks in a row as far as the business end of the operation. How will you keep track of billing? What will you charge your customers? For what services will you charge extra?
Is Linux the right operating system for you? If you have experience with Berkeley-style systems, maybe NetBSD would be a better choice in the short run. If you are in a corporate environment and are setting up a network for your business, maybe you can spend the extra money for the technical support of Solaris or SCO. Then again, Linux has, in my opinion, a better range of services than BSD, and technical support for Linux is available from SSC and others, including several LJ advertisers. Instead of being locked into technical support from one vendor, you have a choice. And why would anyone run SCO?
You should not be under the illusion that becoming an ISP is easy. News will go haywire on you again and again if you are not an expert (you will become one or die trying). The business can be very competitive in different regions, and your dreams of wealth and glitzy nerd-dom might die the hard death of too much work and too little money.
Before investing the time and money in starting up an ISP business, you should be sure of your ability to do it. If in reading through the documentation mentioned above, you had trouble understanding it and are not confident in your ability to pull it off, maybe jumping right in is not the best decision. Again, Linux comes to the rescue. You can get a dial-up account with another ISP and set up a trial system on your PC at home. If you cannot handle a partial news feed, your own mail server, a DNS, and a web daemon, keep hacking at them until you can, and then reconsider starting up. I can think of few deaths worse than being condemned to run a network when you don't know what you're doing, especially if your life's savings are riding on it.
Finally, to all of you startup ISPs out there, I wish you good luck. With skill and hard work, it can be a rewarding business, and you get the satisfaction of meeting interesting customers and introducing them to the Internet. With the tools which Linux provides, there is no reason why you cannot build a first-rate network (and hopefully this article will help, too). Simply be aware that you are not alone in the ISP market, and your competitors will always be breathing down your neck. We might be one of them.
Todd Graham Lewis (email@example.com) is Vice President of Networking at Cheney Communications Company, an ISP in Birmingham, AL. In his spare time he reads 19th-century literature and Linux Documentation. He is working on another HOWTO and Dostoevsky's The Brothers Karamazov.
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