The following embedded x86 machines will run SmallWall.
Some Soekris devices are fully compatible with SmallWall. You will use the generic-pc-serial-xxx image. You will want a system with 128Mb or more ram. Others may work, but are not recommended.
Specifications
net4501-30: 133 Mhz CPU, 64 Mbyte SDRAM, 3 Ethernet, 2 Serial, CF socket, 1 Mini-PCI socket, 3.3V PCI connector.
net4511-30: 100 Mhz CPU, 64 Mbyte SDRAM, 2 Ethernet, 1 Serial, CF socket, 1 Mini-PCI socket, Single PC-Card socket, PoE.
net4521-30: 133 Mhz CPU, 64 Mbyte SDRAM, 2 Ethernet, 1 Serial, CF socket, 1 Mini-PCI socket, Dual PC-Card socket, PoE.
net4526-20: 100 Mhz CPU, 32 Mbyte SDRAM, 1 Ethernet, 1 Serial, 16 Mbyte CF Flash, 2 Mini-PCI sockets, PoE.
net4526-30: 133 Mhz CPU, 64 Mbyte SDRAM, 1 Ethernet, 1 Serial, 64 Mbyte CF Flash, 2 Mini-PCI sockets, PoE.
net4801-50: 266 Mhz CPU, 128 Mbyte SDRAM, 3 Ethernet, 2 serial, USB connector, CF socket, 44 pins IDE connector, 1 Mini-PCI socket, 3.3V PCI connector.
The 5500 series and the 6500 series should all be good choices.
Wireless Router Application Platform (WRAP)
PC Engines ALIX boards are fully compatible with SmallWall. Use the generic-pc-serial images available on the download page.
The Nokia IPxxx boxes were built to run Check Point, but they are standard PC hardware and will run SmallWall.
You can pick up a used IP110 or IP120 for around $100 USD on eBay.
IP110, 120 and 130
Three 10/100 Ethernet interfaces
National GX1 300 MHz processor
64 MB RAM on 110, 128 MB on 120, 256 MB on 130
5 GB hard drive
Two serial ports (auxiliary and console)
Quiet - hard drive is only moving component, no fans
IP330
Three 10/100 Ethernet interfaces
National GX1 300 MHz processor
RAM typically between 64 MB and 256 MB
Hard drive typically ranging from 4-20 GB
Two serial ports (auxiliary and console)
Has case fans, so not quiet like the IP1xx
IP440, 530, 650, 740
Even in the used market, these boxes are usually out of the price range for a typical SmallWall installation, and you can buy or assemble a comparable standard PC for far cheaper. But, if you have one laying around or can find one cheaply, these will run SmallWall. Some of the optional interfaces like HSSI, T-1 CSU/DSU, V.35 and X.21 serial, OC-3 ATM, FDDI, etc. will not work, but the Ethernet will work fine.
There are some tricks to getting SmallWall working on Nokia hardware because the NIC's initially show MAC address ff:ff:ff:ff:ff:ff. For pictures and complete instructions, see this page.
From Wyse Winterminals to Car PCs, a lot of these are in the used market, and if you can get 2 or more network cards in them, they will work.