Almost Internet with SLiRP and PPP
It's the '90s. More and more people around the world have heard of “getting connected to the Internet.” Some of those have actually made the technological, intellectual, and cultural leap into “Cyberspace”. And some of those are using Linux to get connected. I'm part of all three groups. In fact, I've become rather dependent on my Internet connection—it's like having a telephone, only more expensive.
To be connected to the Internet, you used to have only two choices: either a direct (and expensive) Internet connection, like those used by corporations and institutions, or a modem connection into somebody else's machine which had a direct Internet connection, using your computer as if it were a “dumb terminal”. You can still do that today, if you feel like it, but with the increasingly common availability of “real” net connections like SLIP (Serial Line Internet Protocol) and PPP (Point-to-Point Protocol), fewer Internet users really want to feel as if all they have on their desk is a dumb terminal. Yet, for a number of reasons, the only Internet access available to some of us is a dial-up dumb-terminal-ish Internet account, or “shell” account.
Enter SLiRP. SLiRP is a freely available software package, written by Danny Gasparovski (email@example.com), which makes an ordinary shell account act like a SLIP or PPP account. There are other so-called “SLIP emulators” available (one of the more notable of which is The Internet Adaptor—see References sidebar, as well as “terminal multiplexers” such as term, which uses a non-standard protocol between the shell account and the local computer. SLiRP has advantages over both groups, many of which, along with some disadvantages, the author details in the README file accompanying the SLiRP package.
SLiRP does not run on your “local” computer (the one that would otherwise be a dumb terminal), but rather on the “remote” computer (the one that's actually connected to the Internet). In order to install SLiRP properly, you need the following:
A Unix shell account on the remote host
A C compiler available on the remote host
An editor that you know how to use on the remote host
If you're not sure whether you have a compiler or editor available, please contact your system administrator, or someone else who is familiar with your remote site.
The steps involved in installing SLiRP are as follows:
The most recent version of SLiRP available at the time of this writing is slirp-0.95h.tar.gz. See References sidebar to find SLiRP. Once you have the package, “untar” it somewhere useful (such as /usr/local/src)--perhaps with the command tar zxvf slirp-0.95h.tar.gz.
Documentation of many sorts is included in the SLiRP package in slirp-0.95h/docs. Instructions for compiling SLiRP are in slirp-0.95h/docs/README.compiling, the gist of which is: change to the slirp-0.95h/src directory and run the configure program located there (usually by typing ./configure); then build the program by typing make. If you have problems, consult the file slirp-0.95h/docs/README.getting-help.
When you have successfully compiled SLiRP, you will need to put the SLiRP binary somewhere where you can run it. If you don't already have a directory for your own programs, I suggest creating a directory called ~/bin, and then adding it to your PATH in your login scripts. If you're not sure how to do this on your system, check with your system administrator. Then, from the slirp-0.95h/src directory, perform the following commands:
strip slirp cp slirp ~/bin chmod 0700 ~/bin/slirp
(Alternatively, if your site has GNU `install' available, you may perform the above actions in one step with install -s -m 0700 slirp ~/bin.)
This is the tricky bit, partly because SLiRP is an evolving product, and its documentation is not necessarily entirely complete and up-to-date; however, I suggest reading slirp-0.95h/docs/CONFIG and slirp-0.95h/docs/README.ppp before doing anything else. Next, using your favorite text editor, create SLiRP's configuration file, called ~/.slirprc. At the very minimum, you will want to include a baudrate setting. If you're planning on using SLiRP to emulate PPP, you should also include a ppp flag, an asyncmap setting and mtu and mru values. Your .slirprc file might look something like mine:
baudrate 115200 ppp asyncmap 0 mtu 552 mru 552 log start
You will most likely want to adjust the “baudrate” to suit your modem—some experimentation may be necessary. [“baudrate” should really be bits per second, or bpsrate. Even geeks who happen to know that their 14400 bps modems run at 2400 baud shouldn't set the baudrate parameter to 2400.. —ED]
Once you have SLiRP installed and configured, you can start it by simply typing slirp; SLiRP will then attempt to initiate a connection.
|Designing Electronics with Linux||May 22, 2013|
|Dynamic DNS—an Object Lesson in Problem Solving||May 21, 2013|
|Using Salt Stack and Vagrant for Drupal Development||May 20, 2013|
|Making Linux and Android Get Along (It's Not as Hard as It Sounds)||May 16, 2013|
|Drupal Is a Framework: Why Everyone Needs to Understand This||May 15, 2013|
|Home, My Backup Data Center||May 13, 2013|
- Designing Electronics with Linux
- Making Linux and Android Get Along (It's Not as Hard as It Sounds)
- Dynamic DNS—an Object Lesson in Problem Solving
- Using Salt Stack and Vagrant for Drupal Development
- New Products
- What's the tweeting protocol?
- A Topic for Discussion - Open Source Feature-Richness?
- Validate an E-Mail Address with PHP, the Right Way
- Drupal Is a Framework: Why Everyone Needs to Understand This
- Home, My Backup Data Center
2 hours 1 min ago
- Kernel Problem
12 hours 3 min ago
- BASH script to log IPs on public web server
16 hours 30 min ago
20 hours 6 min ago
- Reply to comment | Linux Journal
20 hours 39 min ago
- All the articles you talked
23 hours 2 min ago
- All the articles you talked
23 hours 5 min ago
- All the articles you talked
23 hours 7 min ago
1 day 3 hours ago
- Keeping track of IP address
1 day 5 hours ago
Enter to Win an Adafruit Pi Cobbler Breakout Kit for Raspberry Pi
It's Raspberry Pi month at Linux Journal. Each week in May, Adafruit will be giving away a Pi-related prize to a lucky, randomly drawn LJ reader. Winners will be announced weekly.
Fill out the fields below to enter to win this week's prize-- a Pi Cobbler Breakout Kit for Raspberry Pi.
Congratulations to our winners so far:
- 5-8-13, Pi Starter Pack: Jack Davis
- 5-15-13, Pi Model B 512MB RAM: Patrick Dunn
- 5-21-13, Prototyping Pi Plate Kit: Philip Kirby
- Next winner announced on 5-27-13!
Free Webinar: Hadoop
How to Build an Optimal Hadoop Cluster to Store and Maintain Unlimited Amounts of Data Using Microservers
Realizing the promise of Apache® Hadoop® requires the effective deployment of compute, memory, storage and networking to achieve optimal results. With its flexibility and multitude of options, it is easy to over or under provision the server infrastructure, resulting in poor performance and high TCO. Join us for an in depth, technical discussion with industry experts from leading Hadoop and server companies who will provide insights into the key considerations for designing and deploying an optimal Hadoop cluster.
Some of key questions to be discussed are:
- What is the “typical” Hadoop cluster and what should be installed on the different machine types?
- Why should you consider the typical workload patterns when making your hardware decisions?
- Are all microservers created equal for Hadoop deployments?
- How do I plan for expansion if I require more compute, memory, storage or networking?