device tun 1
options IPFIREWALL #防火墙
options IPFIREWALL_FORWARD #允许透明代理
options IPFIREWALL_VERBOSE #允许防火墙日志
options IPFIREWALL_VERBOSE_LIMIT=100 #限制日志
options IPFIREWALL_DEFAULT_TO_ACCEPT #默认允许所有IP包
options IPDIVERT #启用由ipfw divert使用的转向IP套接字
# To make an SMP kernel, the next two are needed
#options SMP # Symmetric MultiProcessor Kernel
#options APIC_IO # Symmetric (APIC) I/O
device isa
device eisa
device pci
# ATA and ATAPI devices
device ata
device atadisk # ATA disk drives
# SCSI Controllers #没有SCSI设备不需要这段
device ahb # EISA AHA1742 family
device ahc # AHA2940 and onboard AIC7xxx devices
device ahd # AHA39320/29320 and onboard AIC79xx devices
device amd # AMD 53C974 (Tekram DC-390(T))
device isp # Qlogic family
device mpt # LSI-Logic MPT/Fusion
device ncr # NCR/Symbios Logic
device sym # NCR/Symbios Logic (newer chipsets)
options SYM_SETUP_LP_PROBE_MAP=0x40
# Allow ncr to attach legacy NCR devices when
# both sym and ncr are configured
device adv0 at isa?
device adw
device bt0 at isa?
device aha0 at isa?
device aic0 at isa?
device ncv # NCR 53C500
device nsp # Workbit Ninja SCSI-3
device stg # TMC 18C30/18C50
# SCSI peripherals #没有SCSI设备不需要这段
device scbus # SCSI bus (required)
device da # Direct Access (disks)
device sa # Sequential Access (tape etc)
device cd # CD
device pass # Passthrough device (direct SCSI access)
# atkbdc0 controls both the keyboard and the PS/2 mouse
device atkbdc0 at isa? port IO_KBD
device atkbd0 at atkbdc? irq 1 flags 0x1
device vga0 at isa?
# syscons is the default console driver, resembling an SCO console
device sc0 at isa? flags 0x100
# Floating point support - do not disable.
device npx0 at nexus? port IO_NPX irq 13
# Serial (COM) ports
device sio0 at isa? port IO_COM1 flags 0x10 irq 4
# 我用的是8139和Dlink DFE-530TX网卡，大家可根据自己的网卡型号保留或删除
# 使用公共的MII总线控制器代码的PCI以太网适配器
# 注意：一定要保留'device miibus'以确保可用
# PCI Ethernet NICs that use the common MII bus controller code.
# NOTE: Be sure to keep the 'device miibus' line in order to use these NICs!
device miibus # MII bus support
device fxp # Intel EtherExpress PRO/100B (82557, 82558)
device rl # RealTek 8129/8139
device vr # VIA Rhine, Rhine II
device xl # 3Com 3c90x (``Boomerang'', ``Cyclone'')
# Pseudo devices - the number indicates how many units to allocate.
pseudo-device loop # Network loopback
pseudo-device ether # Ethernet support
pseudo-device sl 1 # Kernel SLIP
pseudo-device ppp 1 # Kernel PPP
pseudo-device tun # Packet tunnel.
pseudo-device pty # Pseudo-ttys (telnet etc)
pseudo-device md # Memory "disks"
pseudo-device gif # IPv6 and IPv4 tunneling
pseudo-device faith 1 # IPv6-to-IPv4 relaying (translation)
# The `bpf' pseudo-device enables the Berkeley Packet Filter.
# Be aware of the administrative consequences of enabling this!
pseudo-device bpf #Berkeley packet filter
（完）
如果你用其他型号的网卡，需要察看当前目录的GENERIC 内核文件，找到描述自己的网卡型号的段并将其添加到新的内核文件里。其他的不改直接拷贝过来就可以用了。
接下来编译安装新内核：
# /usr/sbin/config kernel_wwwx #kernel_wwwx为你的内核文件名
# cd ../../compile/kernel_wwwx
# make depend
# make
# make install
重新启动（reboot）
如果系统升级过源代码树，按下面方法编译内核：
# cd /usr/src
# make kernel KERNCONF=kernel_wwwx #kernel_wwwx为你的内核文件名
重新启动