As with all other functions of the firewall feature, IPSec tunnelling requires that the firewall filter driver is loaded and active.
In addition, the device drivers for IPSec must be loaded.
The main IPSec device driver is IPSEC.SYS, and is required. Three additional drivers implement various encryption algorithms; the driver for each algorithm being used must be loaded. These are: MD5.SYS (Keyed MD5), CDMF.SYS (CDMF) and DES.SYS (DES-CBC).
The appropriate device drivers must be loaded in CONFIG.SYS:
DEVICE=x:\MPTN\PROTOCOL\IPSEC.SYS
DEVICE=x:\MPTN\PROTOCOL\MD5.SYS
DEVICE=x:\MPTN\PROTOCOL\CDMF.SYS
DEVICE=x:\MPTN\PROTOCOL\DES.SYS
Where x is the letter of the drive or volume on which MPTS is installed.
Note: Since CDMF is a weaker version of DES, most administrators will likely prefer to use DES exclusively instead. If CDMF is not being used, CDMF.SYS need not be loaded in CONFIG.SYS.