1
1. Intro
Hey! Socket programming got you down? Is this stuff just a little too difficult to figure out from the
man pages? You want to do cool Internet programming, but you don't have time to wade through a gob
of structs trying to figure out if you have to call bind() before you connect(), etc., etc.
Well, guess what! I've already done this nasty business, and I'm dying to share the information
with everyone! You've come to the right place. This document should give the average competent C
programmer the edge s/he needs to get a grip on this networking noise.
And check it out: I've finally caught up with the future (just in the nick of time, too!) and have
updated the Guide for IPv6! Enjoy!
1.1. Audience
This document has been written as a tutorial, not a complete reference. It is probably at its best
when read by individuals who are just starting out with socket programming and are looking for a
foothold. It is certainly not the complete and total guide to sockets programming, by any means.
Hopefully, though, it'll be just enough for those man pages to start making sense... :-)
1.2. Platform and Compiler
The code contained within this document was compiled on a Linux PC using Gnu's gcc compiler.
It should, however, build on just about any platform that uses gcc. Naturally, this doesn't apply if you're
programming for Windows—see the section on Windows programming, below.
1.3. Official Homepage and Books For Sale
This official location of this document is http://beej.us/guide/bgnet/. There you will also
find example code and translations of the guide into various languages.
To buy nicely bound print copies (some call them “books”), visit http://beej.us/guide/url/
bgbuy. I'll appreciate the purchase because it helps sustain my document-writing lifestyle!
1.4. Note for Solaris/SunOS Programmers
When compiling for Solaris or SunOS, you need to specify some extra command-line switches for
linking in the proper libraries. In order to do this, simply add “-lnsl -lsocket -lresolv” to the end
of the compile command, like so:
$ cc -o server server.c -lnsl -lsocket -lresolv
If you still get errors, you could try further adding a “-lxnet” to the end of that command line. I
don't know what that does, exactly, but some people seem to need it.
Another place that you might find problems is in the call to setsockopt(). The prototype differs
from that on my Linux box, so instead of:
int yes=1;
enter this:
char yes='1';
As I don't have a Sun box, I haven't tested any of the above information—it's just what people have
told me through email.
1.5. Note for Windows Programmers
At this point in the guide, historically, I've done a bit of bagging on Windows, simply due to the fact
that I don't like it very much. But I should really be fair and tell you that Windows has a huge install base
and is obviously a perfectly fine operating system.
They say absence makes the heart grow fonder, and in this case, I believe it to be true. (Or maybe
it's age.) But what I can say is that after a decade-plus of not using Microsoft OSes for my personal work,
I'm much happier! As such, I can sit back and safely say, “Sure, feel free to use Windows!” ...Ok yes, it
does make me grit my teeth to say that.
