PII-350 192MB
Ethernet: Realtek Chipset
OS: Windows 2000
P-MMX 266 64MB
Ethernet: 2 x D-Link DFE-530TX (VIA-RHINE chipset)
OS: Linux
Slackware base (distribution)
kernel 2.4.0 (custom compile)
iptables (compile)
iproute2 (compile)
My IP 172.16.48.248
Netmask 255.255.248.0
Gateway 172.16.55.254
IP 10.0.0.1
Netmask 255.255.255.0
Gateway 172.16.55.254 (there is only one default gateway)
IP 10.0.0.2
Netmask 255.255.255.0
Gateway 10.0.0.1
# eth0 is on the Lan where my ISP:s gateway is through a Cable Modem
# eth1 is connected to my Windows Computer by a crossed tp-cable
# 10.0.0.1 and 10.0.0.2 I have set myself
# First the standard ethernet setup /sbin/ifconfig lo 127.0.0.1 # Loopback /sbin/route add -net 127.0.0.0 netmask 255.0.0.0 lo # Route for loopback /sbin/ifconfig eth0 172.16.48.248 broadcast 172.16.55.255 netmask 255.255.248.0 # Outer interface /sbin/ifconfig eth1 10.0.0.1 broadcast 10.0.0.255 netmask 255.255.255.0 # Inner interface /sbin/route add default gw 172.16.55.254 netmask 0.0.0.0 metric 1 # Default gateway
# Pass a parameter to the kernel that it should do forwarding: echo 1 > /proc/sys/net/ipv4/ip_forward
# I have previously done
# echo 200 Burken >> /etc/iproute2/rc_rtables
ip rule add from 10.0.0.2 table Burken # Set route source ip 10.0.0.2 and make rule
ip route add default via 172.16.55.254 dev eth0 table Burken # Set the gateway for source ip 10.0.0.2 to default gateway on outer interface
ip route flush cache # Well, flush
iptables -t nat -I POSTROUTING -s 10.0.0.2 -j SNAT --to-source 172.16.48.248 # This acctually sets the NAT-rule
# States that it should do POSTROUTING where the source-adress is
# 10.0.0.2 and to mask the ip to 172.16.48.248
# "-j SNAT" is the action to be performed