Re: Belkin and wireless modem

On Thu, 10 Apr 2008, in the Usenet newsgroup comp.os.linux.networking, in
article <429512b6-3ba7-476d-bb1d-c7910a211979@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>,
sb5309@xxxxxxxxx wrote:

NOTE: Posting from groups.google.com (or some web-forums) dramatically
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My company's Linux server has the following interfaces:

eth0, eth1, eth3, lo (I don't know why eth2 is missing).

Probably the person who configured the system originally made a typo.

Their settings:

eth1:
DEVICE=eth1
BROADCAST=218.111.104.107
IPADDR=218.111.104.106
NETMASK=255.255.255.255
NETWORK=218.111.104.104
ONBOOT=yes
TYPE=Ethernet
GATEWAY=218.111.104.105

That _looks_ like a Red Hat, Red Hat based, or Red Hat clone, and this
is probably the file /etc/sysconfig/network-scripts/ifcfg-eth1. The
NETMASK value is wrong based on the network and broadcast addresses,
the correct mask is probably '255.255.255.252'. See RFC1878. Also,
you are missing the BOOTPROTO line, though this _may_ cause the system
to default to a static setup.

eth0:
DEVICE=eth0
ONBOOT=yes
BOOTPROTO=static
IPADDR=192.168.42.1
NETMASK=255.255.255.0
GATEWAY=218.111.104.106

"GATEWAY" entry does not belong here. The 'GATEWAY' is the address
of the next hop router, and that can not be any address on "this" box.
(Red Hat and friends uses the term "GATEWAY" to identify the "default
router", which is the system you send packets to for forwarding if ALL
of the other rules will not reach the destination - which generally
means "the rest of the world".)

eth3:
DEVICE=eth3
ONBOOT=yes
IPADDR=192.168.43.1
NETMASK=255.255.255.0
GATEWAY=218.111.104.106

"GATEWAY" entry does not belong here either, and you are missing the
BOOTPROTO line.

There are 2 network segments; one segment with IPs type 192.168.42.*,
default gateway 192.168.42.1; the other of IP type 192.168.43.*,
default gateway 192.168.43.1.

That would be the configuration of the _other_ systems on those segments.

I guess that eth0 and eth3 route thier internet traffic to eth1, which
I believe (not sure) is connected to an external ADSL modem (Lucent
CellPipe).

Did you set up forwarding, and address translation (in the firewall)?
Look at the contents of /etc/sysconfig/network and notice the line
'FORWARD_IPV4=true' or 'FORWARD_IPV4=yes'. Then look at the output of
the command '/sbin/iptables -L'

When I unplug the network cable from the modem, the server shows "eth1
NIC down".

And what is the output of the commands '/sbin/ifconfig eth1' and
'/sbin/route -n' before and after you do this?

When I plug in a Belkin G Wireless Router, the server shows "eth1 NIC
UP 100Mbps".

And what is the output of the commands '/sbin/ifconfig eth1' and
'/sbin/route -n' before and after you do this? If you didn't run the
network scripts, the system probably thinks the 218.111.104.104/30
network is here, and it isn't.

To the Belkin router (with 4 ports and a WAN port) I then connect a
wireless broadband modem via its WAN port (supposedly up to 1Mbps) for
internet access (wireless internet access, not wireless LAN). The
Belkin is configured with the user name and password.

How is the router configured? Is it a DHCP server? How has the DNS
configuration been set? You _REALLY_ need to be reading the manual for
this device, and setting security properly ("1Mbps" doesn't sound
correct at all).

I cannot access the internet via LAN. I am told the Belkin has a fixed
IP 192.168.1.1, which I fail to ping from the server. A laptop
connected directly to the Belkin port shows the router to have IP
192.168.1.1, and it has no problem accessing the internet.

What is the output of '/sbin/ifconfig eth1' and '/sbin/route -n'?
Does this server have any idea what network it is on? You probably
want to change the /etc/sysconfig/network-scripts/ifcfg-eth1 file
to be something like

DEVICE=eth1
BOOTPROTO=dhcp
ONBOOT=yes

and let it get assigned an address, gateway, mask, DNS, and all of the
other crap the DHCP server should be doing. Then for your LAN to have
access, you'll have to re-write the firewall setup rules. I suspect you
will still need to be masquerading, as the Belkin router has no idea
how to reach 192.168.42.x and 192.168.43.x which ought to be fun if
your eth1 interface is going to have a dynamic (changeable) address.

I am think of changing the gateway of eth1 to 192.168.1.1. But I
suppose it is pointless if I can't ping the router.

The server has to have a 192.168.1.x address on eth1 first.

Old guy
.

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