Re: FreeBSD gateway

[Marc Perisa]

Derrick Ryalls wrote:

Hello!
I have installed FreeBSD 4.7 recently, and it seems it does not want to work as a gateway. I have two network cards in my FreeBSD computer, fxp0 for LAN and sis0 for the cable modem. I am new to FreeBSD, so I am confused what the difference between gateways and routers is (I was thinking they link to the same thing). I can ping my FreeBSD box from winxp, I can ping internet from remote session to FreeBSD, but I cannot ping internet from my winxp.
My winxp has ip 192.168.0.1, netmask 255.255.255.0, and gateway 192.168.0.18 settings. Now FreeBSD /etc/rc.conf follows:

gateway_enable="YES"
kern_securelevel_enable="NO"
nfs_reserved_port_only="YES"
ifconfig_sis0="DHCP"
ifconfig_fxp0="inet 192.168.0.18 netmask 255.255.255.0" #router_enable="YES" # from handbook gateway_enable="YES" firewall_enable="YES" firewall_type="OPEN" natd_enable="YES" natd_interface="sis0"

>>natd_flags="" #/ handbook

Are your ip's reversed?  I think the gateway should have the .1 address
and the xp box should use the .18

Nope. He set his FreeBSD box to the IP 192.168.0.18 and his Windows XP box to 192.168.0.1 . All is ok with that. It is only uncommon to do. Normally you would give the defaultgateway for a network x.y.z.1 or x.y.z.254 . But it is not forbidden to set it to any IP in that subnet.

Are you using the default kernel?  If so, you will need to add a couple
lines are recompile.

options         IPFIREWALL              #firewall
options         IPDIVERT                #divert sockets

as for the difference between a router and a gateway, a gateway is a
machine to deal with going from one network (lan) to another network
(wan), I think.

From your point of view (as needed for this problem) routers and gateways are the same. In this case the FreeBSD box is acting as a router for your internal net to the Internet. A simple router would do the same. But for more complex routing you have to either setup gated (or similar software) or add all rules (if they are static) by hand.
A gateway is the simplest form of a router.

The last two lines from dmesg:
IP packet filtering initialized, divert disabled, rule-based forwarding enabled, default to deny, logging disabled
ip_fw_ctl: invalid command

That hints to a problem with the /etc/rc.firewall script (which is called when you add to /etc/rc.conf firewall_enable="YES").

Please provide us with the output of "ipfw list". (You have to do that as root of course). I think your firewall ruleset is not tuned for a gateway situation.

Hope that helps

Marc



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