how do i set up an ip forwarding service ?

ursvik · **Posted:** Tue Apr 04, 2006 7:32 am

The problem: My pda (familiar/opie), connects via usb on usb0, it has ip 192.168.66.202, my usb interface has ip 192.168.66.200 netmask is 255.255.255.0 I can ping both ways, pda to zen and zen to pda.

With rc.ip_forward enabled i can ping the "outbound" interface on the zen box (eth0, 192.168.0.100).

eth0 is on dhcp, usb0 is static.

I got no further than that, could not ping any other machine on the network from the pda. So i started reading up on masquerading and forwarding, and found tips on how to create an iptable rule to do masquerading. The rule went into rc.netfilter, and i added netfilter rules for the services i run on the zen box too.

this is how rc.netfilter, "activate_rules" looks right now:

Code:

# HERE YOU MAY DEFINE YOUR RULES AS IPTABLES COMMANDS
activate_rules() {

  iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
  iptables -t filter -A INPUT -p tcp --dport 22 -j ACCEPT # ssh
  iptables -t filter -A INPUT -p tcp --dport 80 -j ACCEPT
  iptables -t filter -A INPUT -p tcp --dport 111 -j ACCEPT
  iptables -t filter -A INPUT -p udp --dport 111 -j ACCEPT
  iptables -t filter -A INPUT -p udp --dport 137 -j ACCEPT
  iptables -t filter -A INPUT -p udp --dport 138 -j ACCEPT
  iptables -t filter -A INPUT -p tcp --dport 139 -j ACCEPT
  iptables -t filter -A INPUT -p tcp --dport 631 -j ACCEPT
  iptables -t filter -A INPUT -p udp --dport 631 -j ACCEPT
  iptables -t filter -A INPUT -p tcp --dport 901 -j ACCEPT
  iptables -t filter -A INPUT -p tcp --dport 902 -j ACCEPT
  iptables -t filter -A INPUT -p tcp --dport 6000 -j ACCEPT
  iptables -t filter -A OUTPUT -j ACCEPT

}

And how does it work ?

really bad !

Now i can only ping from the pda to 192.168.66.200, not to 192.168.0.100, nor anywhere else in the world.

I want to access internet from the pda, can anyone help ?

Ursvik

edit:
Some further studies and rc.netfilter restarts later i found the problem...
rc.netfilter by default blocks all forwarding, so i must un-block it in my rule set.
The new rules looks like this:

Code:

# HERE YOU MAY DEFINE YOUR RULES AS IPTABLES COMMANDS
activate_rules() {

  iptables -A FORWARD -i usb0 -j ACCEPT #allow forwarding from usb0
  iptables -A FORWARD -o usb0 -j ACCEPT #allow forwarding to usb0
  iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE #allow NAT
  iptables -t filter -A INPUT -p icmp -j ACCEPT # ping
  iptables -t filter -A INPUT -p tcp --dport 22 -j ACCEPT # ssh
.... continues as above

i am now happily using familiar with an internet connection

how do i set up an ip forwarding service ?

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