This system has been run on a 486SX33 with 8 megabytes of RAM. It didn't run very well though, it had trouble handling heavy traffic.
It doesn't take much more to make it work though. This system does work very well on a Pentium 75 with 16 megs of RAM, using an LRP distribution running off of a floppy, with a 6 meg ramdisk, and 10 megs of main memory. I've tested this setup by running a 700kbit RealVideo stream through it for over an hour.
I now typically run it on Pentium 90s, as their PCI clocking plays nicer with cheap 100Mbit Ethernet cards.
This system works with both the 2.0 and 2.2 kernels. The script to keep the tunnel up requires a reasonably modern bash. I have however noticed that certain distribution's versions of bash don't play too well with the script.
Also, if someone could help me refine my scripts (or even write an executable) that would help a lot. I'm not sure why, but even my own bash doesn't follow the rules and doesn't seem to interpret signals correctly. If you do make any improvements, please email me at firstname.lastname@example.org.