[garant:~/qemu] % cat start_freebsd.sh
#!/bin/sh

# qemu-img create qemu_freebsd.img 512M
# qemu -cdrom /dev/acd0 -boot d qemu_freebsd.img &
# qemu -k ru -net tap,script=tun_up_freebsd.sh -net nic qemu_freebsd.img &
qemu -net tap,script=tun_up_freebsd.sh -net nic qemu_freebsd.img &

/etc/rc.d/named stop
sleep 3
/etc/rc.d/named start

[garant:~/qemu] % cat tun_up_freebsd.sh
#!/bin/sh

ifconfig $1 192.168.113.1 netmask 255.255.255.0