ipfw -- interface for firewall, packet scheduler, NAT and so on.
It is comprised of several components: the kernel firewall filter rule processor and its integrated packet accounting facility, the logging facility, NAT, a forward facility, a bridge facility, and an ipstealth facility.
Note that the `dummynet` traffic shaper is not merged.
For example, if you have an extra FreeBSD kernel module, and want to
compile it into F-Stack, you can do it like this:
```
cd f-stack/lib
export "KMOD_SRCS=/your/kmod/path/a.c /your/kmod/path/b.c"
export "CONF_CFLAGS=-I/your/kmod/path"
make
```
Changes:
Remove directory `ipc`, and add a new directory `compat`.
Directory `compat` includes some FreeBSD source files to be compatible
with Linux.
Port FreeBSD ifconfig to F-Stack.