slbd

OpenBSD server load balancing using PF

What is It?

The slbd project aims to produce stable, production-quality code to monitor web and other TCP-based servers, allowing for server load balancing (SLB) functionality through OpenBSD's PF packet filter.

Requirements

In order to run slbd, you will need the following things:

x86-based system running OpenBSD 3.3+, FreeBSD 6.0+
OpenBSD compiler tools (gcc, make)
OpenBSD native pthreads
PF must be enabled in your kernel (GENERIC includes it)

Download

The current release is 1.3, released October 21, 2006.

Filename		md5sum
slbd-1.3.tar.gz		`ac10353d513694fcc2574aa352360ae9`
slbd-1.2.tar.gz		`fecf5a6a8abd456940b64f7a7b0ac37a`
slbd-1.1.tar.gz		`7f20a9cd32fd91daf03557124e9197cf`
slbd-1.0.tar.gz		`5a8f253bc3a5e8d88a8d527de2b7da37`

Browse other files from the sf.net project home page by clicking here.

Frequently Asked Questions

Q. Will this (ever) work on Linux?
A. No.
Q. Do you have any plans to support the other BSDs?
A. Patches are gladly accepted, although I can't make any guarantees of quality or testing on my end. I really don't have much time to work on this, so my work will tend to be sporadic but intensive, and fundamentally based on what i need to get done for my employer. But others can certainly help if they'd like to.
Q. Why do you use getcap(3) configuration syntax?
A. It's included in the base distribution, so there are no extra libraries needed. Also, I'm lazy and don't want to mess with YACC. I've tried to keep everything as plain-vanilla as possible. getcap(3) isn't hard to learn, but it is just a little picky about syntax.
Q. getcap(3) won't let me use colons in my expect strings or URLs. Is there any way around this?
A. YES! getcap(3) uses escape sequences to express prohibited characters. See the man page for more information. Just for kicks, the escape sequence for a colon is "\c" (obviously without the double-quotes).
Q. This seems like it's mostly geared toward web servers. Why is that?
A. Because it is. That's what we use load balancers for, so that's the major focus now. Maybe eventually we'll do more fun stuff.
Q. It doesn't work for me. What now?
A. I don't know what to tell you. Look at your syslog messages to see if it is trying to tell you something. You can email me if you want or post on the SourceForge message boards, but don't hold your breath. Remember, this is BSD-licensed software and implies no guarantee or warranty.
Q. OpenBSD sucks/OS <whatever> is better!
A. Then don't use OpenBSD.

Thanks go to...

my employer, Silas Partners, for allowing me to release the code for the project
SourceForge
The OpenBSD team for a tight operating system.
Daniel Hartmeier, for spearheading PF development and providing assistance on the PF mailing list.

Contact Us

The current maintainer can be reached at the address below. Just replace "spamfree.net" with "users.sourceforge.net".
wlmarque@spamfree.net
The author can be reached at the address below. Just replace "spamfree.net" with "users.sourceforge.net".
jonkeim@spamfree.net

Version History

Future (what the crackpipe tells me to do)

plugin infrastructure for polling modules
run a command when a poll fails
run a command when switching to sitedown server
HTTPS healthcheck polling
DNS polling and redirection (UDP)

1.3 (Released on October 21, 2006)

support for OpenBSD 3.7

1.2 (Released belatedly on July 15, 2005)

switch to new ioctl interface using DIOCX{BEGIN,COMMIT,ROLLBACK}
put pf redirection rules in an anchored ruleset instead of main
more extensive command line options
full, verified support for OpenBSD 3.5 and above (new ioctl(2) interface)

1.1 (Released May 11, 2004)

general TCP expect polling (still only plain text strings)
seems to work with OpenBSD 3.5, reports of success or failure welcome.

1.0 (Released December 2003)

HTTP GET/HEAD healthcheck polling, allowing basic substring matching in HTTP response
working with OpenBSD 3.4 and 3.3
ability to send traffic to a "This site is down for maintenance" web server if no real services are available
round-robin load distribution (included in PF)