"Linux Gazette...making Linux just a little more fun!"

The Answer Guy

By James T. Dennis, answerguy@ssc.com
Starshine Technical Services, http://www.starshine.org/

Permission to Set up a Linux Server

From ChipX on 20 Aug 1998

Hi, OK, just a quick question (sort of)...

My friend came over one day and we were just surfing like usual (using Win95).

He asked if he could check his mail; I said "Sure." So he opens up telnet and logs onto a friend's RedHat Linux 4.2 Server. He checks mail, updates his finger, and leaves.

I really need to know how to set up a server of my own.

Do I need my isp's permission or some junk like that, cuz they wont be willing to give up any of their ethernet for me and my linux box

Alright, I finally figured out what you were asking. It took a little work, though.

First note: when you set up a Linux system it defaults to providing many services. It is already a "server."

What you seem to be asking is: "How do I make my server accessible via the Internet?"

As you surmised you would have to make arrangements with some ISP to have some dedicated (or at least "dial on demand") connection to the net, or to "co-locate" your hardware with them.

There are a number of ISP's that provide co-location services. This is where you provide a system that they plug into their network (and power). Generally these are moderately expensive services (about $150 to $500 per month usually with a limited average bandwidth utilization per month).

Some of these plug you into their ethernet, others provide a null modem (serial) connection over which you'd configure a "local" (direct) PPP link. This allows them to effectively limit the amount of bandwidth you're using. (The latest 2.1 Linux kernels have an experimental "shaper" interface that allows one to limit bandwidth utilization on ethernet --- but I don't know of any ISP that's using that).

I know some businesses that co-locate an extra server for redundancy. If their dedicated network connection gets hit by the proverbial (and sometime very real) 'backhoe' then their web site and mail server is still accessible to their customers. This is relatively low cost to companies that are used to paying for T-1, T-3, or fiber charges.

This brings up to the second option. You can get a dedicated connection to your home or office. These range from 28.8 dial-up over POTS (plain old telephone service) to OC-48 (optical connections --- even past 622Mbps). As you might expect most of these are prohibitively expensive for home use (not to mention potential zoning and regulatory issues).

For practical purposes you have the following options for home and SOHO (small office, home office) dedicated connections:

modem over POTS:

least expensive, might be as low as $130 (US) per month. Slowest. As discussed in my articles about modems you usually won't get 56Kbps out of a "56K" modem.

ISDN (Centrex or not):

This is usually at least $200/mo. Centrex is a little confusing. Typically it allows you and your ISP, if you are located in the same telephone CO (central office), to have an ISDN line that is essentially an extension of your ISP's office. This typically just eliminates the "per-minute" charges of keeping the ISDN line up. It also limits your ISDN line so that it can only be used with that ISP. (This also implies a very limited selection of ISP's for each user).

DSL:

Not available in all areas. Somewhat confusing right now since it is a fairly recent offering. Basically DSL takes advantage of an old obscure feature in the pricing structure and responsibilities of US phone companies. They used to provide "dry copper" lines (that is telephone wires with no dial-tone or signal) to alarm companies and similar services. Using these lines and connecting DSL routers at each end (rather than alarm monitoring equipment) one can get various speeds (depending on the distances between client, CO, and ISP).

DSL typically costs about $300/mo where it's available.

If I was getting a DSL line I'd get it from Idiom (http://www.idiom.com) or some other Covad partner (http://www.covad.com). I know the owner and founder of Idiom, and one of the principles of Covad. Those are both SF Bay Area companies.

56K leased line:

(I'm not a telco expert but I think this is the same as a "fractional T1" --- that is that is a a fraction, 1/24th of a T-1 --- which in turn is a bundle of 24 channels for a total of 1.54Mbps). This is about as much as any sane person would pay to put in his or her home. They cost about $300 or more per month.

cablemodem:

These are very fast, and only available in a very limited number of places. Also they frequently limit your ability to provide services (through packet filtering or by periodically disconnecting you and assigning new IP addresses. While they sound great for web

Frame Relay:

I've seen these in various speeds, from 56K or 64Kbps to 1.5Mbps and in various prices ranging from $200 per month to over $1000.

Wireless:

A couple of providers in the Silicon Valley (and San Francisco Bay Area) offer wireless dedicated connections. One of them is Innetix (http://www.innetix.com)

Conceivably an ISP could provide "dialout" or "service on demand" services --- that is that they could dynamically dial your server when TCP/IP traffic is destined for your site. (It would work almost the same way that your copy of diald allows your system to dynamically call your ISP --- only the underlying routes would be different).

I've never heard of a company that actually offered this service and I doubt that there's any advantage for them to do so. This would probably be quite expensive for them --- and there's probably almost no demand for it (I doubt that one customer in a thousand would understand or care about such a service --- and I can see any pricing niche that would make it worthwhile).

I only mention as a theoretical possibility.

X is a communications protocol for windowing (GUI) and keyboard/mouse events. The X Window System provides a client/server windowing environment --- which allows programs on your local machine, and on selected remote systems, to act as clients on your "display server" (a display is one or more screens, a keyboard and a mouse and/or other pointing device).

This is why you call the program that you run on your Linux system an "X server" --- because it provides display services to programs like 'xterm' 'netscape' etc. The fact that most of these programs are usually running on the same host as the server is of no consequence to X. The X server communicates with all of its clients via sockets.

Those are unix domain sockets ("s" special nodes on your file system --- usually under /tmp) for most localhost clients, internet domain sockets (TCP/IP networking) for most others).

So, I suppose you can do "this" with X (that is, you could have an ISP co-located a server on the Internet, or you could have a dedicated connection fed into your home such that you could allow access to an X server from any client on the Internet. This would be horrible from a security standpoint --- but that's not something you've expressed any concern about.

Shifting into "requirements analysis" mode we ask:

What information, applications and resources to you want/need to make available to whom?

... which leads to a more fundamental requirements question:

Who are the involved parties? (You, and each person or class of persons to whom you would like to provide access to the aforementioned resources).

You can use these two lists (resources, parties/customers) to build a table of "business relationships" (even if this isn't really a business, the principle applies --- you relate groups/users to the resources with verbs like "read" "write" "execute" "append/add" etc.

When you have a clear understanding of these things you can evaluate and prioritize them. That is to say: you can place values on each of these relationships. You may find that many the items you listed are not really requirements --- but are really preferences or constraints. That's fine, keep them on the list.

You could then look at your possible approaches (from the list above, and by doing additional research into ISP offerings in your area). All possible designs/plans which fit your requirements without violating any of your constraints form a "solution space." This may be an empty set (there may be not solutions to your set of requirements within your stated constraints). If there are multiple options a mapping of these overlaid on your preferences may find an optimal solution (that's why you prioritize/evaluate the preferences --- so you can do sums and scoring).

At that point you'd be in a position to do a cost/benefit analysis. Undoubtedly costs/pricing formed some of your constraints. Presumably your preference (all other things being equal) would be to pay less. However, it is possible that you're costs will exceed perceived or potential benefits in such a way as to convince you to abandon the solution set (and a whole project).

Actually all you said about your requirements was that you "need to know how to ...." --- hopefully you now "know"; presumably you are, or were, considering actually setting something up and I'll have to guess beyond that.

All I can guess about your requirements was that you want to be able to remotely get your mail, telnet to your machine, and update your .plan (finger info). You currently think you want to be able to do this "over the Internet."

I'm not sure that you've really considered alternatives regarding this last one. If you connect a modem to your Linux box at home you can dial in and use it from anywhere that you can get at a modem and dial your home number. Unless you are a real globetrotter your home is probably a local call to you most of the time. In addition if your area has "Ricochet" or "Metricom" or [Ricochet is the product sold or leased by Metricom. -- Heather] any similar service it may be that you can get a wireless "modem" (provides a Hayes compatible AT command set and serial interface to your computer) with optional dial out service. (This allows you to use a "Ricochet" on your laptop, from the local coffee house or wherever you can get a signal to dial into your machine at home).

Actually, oddly enough, this service has a strange idea of locality. I subscribe to it in the SF Bay Area. This lets me dial to any modem number in the 408, 415, 650, 510, and nearby area codes. It also allows me to dial to 800 numbers. I can dial to these, toll free and without connect time charges from any where that Metricom's service extends.

Thus I've dialed into my home computer from the Burbank Airport near L.A. and from a hotel lobby in Seattle while I was at a USENIX conference.

Another thing that's not evident from your question is just what benefits you hope to get from all of this. Is it just "coolness" --- so you can do the same thing your friend did? If so, see if you can get an account on this other friend's machine. Is it convenience? Do you have any security concerns? How much is it worth do have this much "coolness" or convenience?

Copyright © 1998, James T. Dennis
Published in Linux Gazette Issue 32 September 1998

	phreak	abandon	javaterm	BBS	flaws	doslinux	resume
	softwindows	convert	apache	emulate	database	distrib	proxy
	disable	DVI	superblock	serial	permission	detach	cdr
rs422	modem	notfound	tuning	libc5	startup	clock	ping
accounts	lilo	NDS	95slow	nonlinux	progenv	cluster	ftpd