Linux Networking: Using Ipchains - page 4

Multiple Machines, A Single Connection

The ip_masq files are actually drivers loaded using the modprobe program. The file names start with ip_masq_. The files are normally found in the /lib/modules/version/ipv4 directory where the version subdirectory is the version number of kernel as in /lib/modules/2.2.15-2.5.0/ipv4.

The typical collection of masquerading modules includes:

     ip_masq_autofw.o
     ip_masq_cuseeme.o
     ip_masq_ftp.o
     ip_masq_irc.o
     ip_masq_mfw.o
     ip_masq_portfw.o
     ip_masq_quake.o
     ip_masq_raudio.o
     ip_masq_user.o
     ip_masq_vdolive.o

FTP, IRC, and Quake may be familiar, but protocols like CuSeeME streaming video may not be. Protocols installed but not used simply use up RAM. Most users will want FTP and IRC support.

These modules are used only if the masquerade support is set up using ipchains. The typical command line for loading these modules is:

/sbin/modprobe ip_masq_ftp

Note that the .o is not needed. A module does not need to be loaded if the associated application is not used. Loading a module that will not be used simply uses more memory, but does not impact ipchains.