Should route, but doesn't

Desired Topology:

Internet---Cable Modem---Netgear FR114P 192.168.2.1
|
192.168.2.0/255.255.255.0 |
|
eth1 - dhcp (192.168.2.33-63)
RedHat 7.2
eth0 192.168.1.254
|
192.168.1.0/255.255.255.0 Hub
|
|--RedHat 8.0 192.168.1.1
|--etc

The Netgear box acts as DHCP server for 192.168.2.0
The RedHat 7.2 box acts as DHCP server for 192.168.1.0

I bought the Netgear box last June. Before that the RedHat 7.2 box was
connected directly to the cable modem, with IP Masq. When I bought the
Netgear box, I quit allowing any incoming connections. Now I'd like to
make some select openings, but first want the RedHat 7.2 box between any
open ports an my LAN. At the moment, there is no firewalling in the
RH7.2 box. (That will change in the future, before I open any ports.)

I've set /proc/sys/net/ipv4/ip_forward to "1"
The ip tables are all set to default policy ACCEPT.

It doesn't route.
Packets get from the RedHat 7.2 box to my LAN or to the Internet.
Packets from the RedHat 8.0 box get to the RedHat 7.2 box.
Packets from the RedHat 8.0 box do not get to the Internet.

Here's the answer to your next question:

[root@tomcat log]# netstat -Nr
Kernel IP routing table
Destination Gateway Genmask Flags MSS Window irtt Iface
192.168.1.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0
192.168.2.0 0.0.0.0 255.255.255.0 U 0 0 0 eth1
127.0.0.0 0.0.0.0 255.0.0.0 U 0 0 0 lo
0.0.0.0 192.168.2.1 0.0.0.0 UG 0 0 0 eth1

I tried a traceroute from the RH8.0 box while watching the adapters on
the RH7.2 box with ifconfig. Packets were coming in on eth0, but
nothing was leaving on eth1.

I added a -j LOG rule to the FORWARD chain, and was able to see packets
coming in from the correct IP on eth0, and getting sent to eth1.

But no forwarded packets come out of eth1.

I thought that perhaps the problem is that both subnets are in the
RFC1918 allocation, and aren't supposed to be routed. But then I
searched /proc for some sort of rfc1918 switch, to no avail.

Any suggestions as to what I try next?

Thanks,
Dale Pontius

On Mon, 05 Jan 2004 04:42:55 GMT, (E-Mail Removed)lid (Dale Pontius)
wrote:

>Desired Topology:
>
>Internet---Cable Modem---Netgear FR114P 192.168.2.1
> |
>192.168.2.0/255.255.255.0 |
> |
> eth1 - dhcp (192.168.2.33-63)
> RedHat 7.2
> eth0 192.168.1.254
> |
>192.168.1.0/255.255.255.0 Hub
> |
> |--RedHat 8.0 192.168.1.1
> |--etc
>
>The Netgear box acts as DHCP server for 192.168.2.0
>The RedHat 7.2 box acts as DHCP server for 192.168.1.0
>
>I bought the Netgear box last June. Before that the RedHat 7.2 box was
>connected directly to the cable modem, with IP Masq. When I bought the
>Netgear box, I quit allowing any incoming connections. Now I'd like to
>make some select openings, but first want the RedHat 7.2 box between any
>open ports an my LAN. At the moment, there is no firewalling in the
>RH7.2 box. (That will change in the future, before I open any ports.)
>
>I've set /proc/sys/net/ipv4/ip_forward to "1"
>The ip tables are all set to default policy ACCEPT.
>
>It doesn't route.
>Packets get from the RedHat 7.2 box to my LAN or to the Internet.
>Packets from the RedHat 8.0 box get to the RedHat 7.2 box.
>Packets from the RedHat 8.0 box do not get to the Internet.
>
>Here's the answer to your next question:
>
>[root@tomcat log]# netstat -Nr
>Kernel IP routing table
>Destination Gateway Genmask Flags MSS Window irtt Iface
>192.168.1.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0
>192.168.2.0 0.0.0.0 255.255.255.0 U 0 0 0 eth1
>127.0.0.0 0.0.0.0 255.0.0.0 U 0 0 0 lo
>0.0.0.0 192.168.2.1 0.0.0.0 UG 0 0 0 eth1
>
>I tried a traceroute from the RH8.0 box while watching the adapters on
>the RH7.2 box with ifconfig. Packets were coming in on eth0, but
>nothing was leaving on eth1.
>
>I added a -j LOG rule to the FORWARD chain, and was able to see packets
>coming in from the correct IP on eth0, and getting sent to eth1.
>
>But no forwarded packets come out of eth1.
>
>I thought that perhaps the problem is that both subnets are in the
>RFC1918 allocation, and aren't supposed to be routed. But then I
>searched /proc for some sort of rfc1918 switch, to no avail.

You just can't route them on the internet.

Question: Can 192.168.2.1 and 192.168.1.1 ping each other?

On Mon, 05 Jan 2004 04:42:55 GMT, Dale Pontius <(E-Mail Removed)> wrote:
> Desired Topology:
>
> Internet---Cable Modem---Netgear FR114P 192.168.2.1
> |
> 192.168.2.0/255.255.255.0 |
> |
> eth1 - dhcp (192.168.2.33-63)
> RedHat 7.2
> eth0 192.168.1.254
> |
> 192.168.1.0/255.255.255.0 Hub
> |
> |--RedHat 8.0 192.168.1.1
> |--etc
>
> The Netgear box acts as DHCP server for 192.168.2.0
> The RedHat 7.2 box acts as DHCP server for 192.168.1.0
>
> I bought the Netgear box last June. Before that the RedHat 7.2 box was
> connected directly to the cable modem, with IP Masq. When I bought the
> Netgear box, I quit allowing any incoming connections. Now I'd like to
> make some select openings, but first want the RedHat 7.2 box between any
> open ports an my LAN. At the moment, there is no firewalling in the
> RH7.2 box. (That will change in the future, before I open any ports.)
>
> I've set /proc/sys/net/ipv4/ip_forward to "1"
> The ip tables are all set to default policy ACCEPT.
>
> It doesn't route.
> Packets get from the RedHat 7.2 box to my LAN or to the Internet.
> Packets from the RedHat 8.0 box get to the RedHat 7.2 box.
> Packets from the RedHat 8.0 box do not get to the Internet.
>
> Here's the answer to your next question:
>
> [root@tomcat log]# netstat -Nr
> Kernel IP routing table
> Destination Gateway Genmask Flags MSS Window irtt Iface
> 192.168.1.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0
> 192.168.2.0 0.0.0.0 255.255.255.0 U 0 0 0 eth1
> 127.0.0.0 0.0.0.0 255.0.0.0 U 0 0 0 lo
> 0.0.0.0 192.168.2.1 0.0.0.0 UG 0 0 0 eth1
>
> I tried a traceroute from the RH8.0 box while watching the adapters on
> the RH7.2 box with ifconfig. Packets were coming in on eth0, but
> nothing was leaving on eth1.

tcpdump on the 7.2 interfaces may reveal more than traceroute, like that
the Netgear is ignoring any LAN IPs not on its 192.168.2.0/24 LAN, hence
no 192.168.1.0/24 packets being passed towards it.

> I added a -j LOG rule to the FORWARD chain, and was able to see packets
> coming in from the correct IP on eth0, and getting sent to eth1.
>
> But no forwarded packets come out of eth1.
>
> Any suggestions as to what I try next?

Does the Netgear FR114P have configurable LAN routing (gateway for
192.168.1.0/24 network)? If not then the RH 7.2 box has to masquerade its
eth0 network as its eth1 IP.

--
David Efflandt - All spam ignored http://www.de-srv.com/

Dale Pontius wrote:

> Desired Topology:
>
> Internet---Cable Modem---Netgear FR114P 192.168.2.1
> |
> 192.168.2.0/255.255.255.0 |
> |
> eth1 - dhcp (192.168.2.33-63)
> RedHat 7.2
> eth0 192.168.1.254
> |
> 192.168.1.0/255.255.255.0 Hub
> |
> |--RedHat 8.0 192.168.1.1
> |--etc
>
> The Netgear box acts as DHCP server for 192.168.2.0
> The RedHat 7.2 box acts as DHCP server for 192.168.1.0
>
> I bought the Netgear box last June. Before that the RedHat 7.2 box was
> connected directly to the cable modem, with IP Masq. When I bought the
> Netgear box, I quit allowing any incoming connections. Now I'd like to
> make some select openings, but first want the RedHat 7.2 box between any
> open ports an my LAN. At the moment, there is no firewalling in the
> RH7.2 box. (That will change in the future, before I open any ports.)
>
> I've set /proc/sys/net/ipv4/ip_forward to "1"
> The ip tables are all set to default policy ACCEPT.
>
> It doesn't route.
> Packets get from the RedHat 7.2 box to my LAN or to the Internet.
> Packets from the RedHat 8.0 box get to the RedHat 7.2 box.
> Packets from the RedHat 8.0 box do not get to the Internet.
>
> Here's the answer to your next question:
>
> [root@tomcat log]# netstat -Nr
> Kernel IP routing table
> Destination Gateway Genmask Flags MSS Window irtt
> Iface
> 192.168.1.0 0.0.0.0 255.255.255.0 U 0 0 0
> eth0
> 192.168.2.0 0.0.0.0 255.255.255.0 U 0 0 0
> eth1
> 127.0.0.0 0.0.0.0 255.0.0.0 U 0 0 0
> lo
> 0.0.0.0 192.168.2.1 0.0.0.0 UG 0 0 0
> eth1
>
> I tried a traceroute from the RH8.0 box while watching the adapters on
> the RH7.2 box with ifconfig. Packets were coming in on eth0, but
> nothing was leaving on eth1.

You might find it useful to watch the packets with tcpdump, something like :

tcpdump -i eth1
... and in another xterm ..
tcpdump -i eth0

keep in mind that if you are telnetted/ssh'd into the box you are running
tcpdump, you might want to exclude your own traffic so that you don't end
up in an infinite loop, something like

tcpdump -i eth1 src or dst port not ssh


Or if you don't like the output of tcpdump, you can use ethereal to make it
pretty for you ..

tcpdump -i eth1 -s 0 -w packets.dump

ethereal packets.dump

>
> I added a -j LOG rule to the FORWARD chain, and was able to see packets
> coming in from the correct IP on eth0, and getting sent to eth1.
>
> But no forwarded packets come out of eth1.
>
> I thought that perhaps the problem is that both subnets are in the
> RFC1918 allocation, and aren't supposed to be routed. But then I
> searched /proc for some sort of rfc1918 switch, to no avail.

What you'd done is ok, with the private subnets. It's really only sensible
configured routers on the internet that will drop the private subnets.

>
> Any suggestions as to what I try next?
>

Turn off firewalling, just in case it's dropping packets, but leave on the
masq stuff.

What's the routing table on the RH8.0 box ? It should include a reference to
the fact that either 192.168.1.254 is the default gateway OR that the
192.168.2.x subnet is reachable via 192.168.1.254

tcpdump might give you some clues as to why packets are getting dropped, you
should be able to see tcpdump decode the ICMP errors, or perhaps even ARP
queries.

> Thanks,
> Dale Pontius

In article <tbdKb.78757$(E-Mail Removed)>,
s <(E-Mail Removed)> writes:
> Dale Pontius wrote:
>
>> Desired Topology:
>>
>> Internet---Cable Modem---Netgear FR114P 192.168.2.1
>> |
>> 192.168.2.0/255.255.255.0 |
>> |
>> eth1 - dhcp (192.168.2.33-63)
>> RedHat 7.2
>> eth0 192.168.1.254
>> |
>> 192.168.1.0/255.255.255.0 Hub
>> |
>> |--RedHat 8.0 192.168.1.1
>> |--etc
>>
>> The Netgear box acts as DHCP server for 192.168.2.0
>> The RedHat 7.2 box acts as DHCP server for 192.168.1.0
>>
>> I bought the Netgear box last June. Before that the RedHat 7.2 box was
>> connected directly to the cable modem, with IP Masq. When I bought the
>> Netgear box, I quit allowing any incoming connections. Now I'd like to
>> make some select openings, but first want the RedHat 7.2 box between any
>> open ports an my LAN. At the moment, there is no firewalling in the
>> RH7.2 box. (That will change in the future, before I open any ports.)
>>
>> I've set /proc/sys/net/ipv4/ip_forward to "1"
>> The ip tables are all set to default policy ACCEPT.
>>
>> It doesn't route.
>> Packets get from the RedHat 7.2 box to my LAN or to the Internet.
>> Packets from the RedHat 8.0 box get to the RedHat 7.2 box.
>> Packets from the RedHat 8.0 box do not get to the Internet.
>>
>> Here's the answer to your next question:
>>
>> [root@tomcat log]# netstat -Nr
>> Kernel IP routing table
>> Destination Gateway Genmask Flags MSS Window irtt
>> Iface
>> 192.168.1.0 0.0.0.0 255.255.255.0 U 0 0 0
>> eth0
>> 192.168.2.0 0.0.0.0 255.255.255.0 U 0 0 0
>> eth1
>> 127.0.0.0 0.0.0.0 255.0.0.0 U 0 0 0
>> lo
>> 0.0.0.0 192.168.2.1 0.0.0.0 UG 0 0 0
>> eth1
>>
>> I tried a traceroute from the RH8.0 box while watching the adapters on
>> the RH7.2 box with ifconfig. Packets were coming in on eth0, but
>> nothing was leaving on eth1.
>
> You might find it useful to watch the packets with tcpdump, something like :
>
> tcpdump -i eth1
> .. and in another xterm ..
> tcpdump -i eth0
>
> keep in mind that if you are telnetted/ssh'd into the box you are running
> tcpdump, you might want to exclude your own traffic so that you don't end
> up in an infinite loop, something like
>
> tcpdump -i eth1 src or dst port not ssh
>
>
> Or if you don't like the output of tcpdump, you can use ethereal to make it
> pretty for you ..
>
> tcpdump -i eth1 -s 0 -w packets.dump
>
> ethereal packets.dump
>
>>
>> I added a -j LOG rule to the FORWARD chain, and was able to see packets
>> coming in from the correct IP on eth0, and getting sent to eth1.
>>
>> But no forwarded packets come out of eth1.
>>
>> I thought that perhaps the problem is that both subnets are in the
>> RFC1918 allocation, and aren't supposed to be routed. But then I
>> searched /proc for some sort of rfc1918 switch, to no avail.
>
> What you'd done is ok, with the private subnets. It's really only sensible
> configured routers on the internet that will drop the private subnets.
>
>>
>> Any suggestions as to what I try next?
>>
>
> Turn off firewalling, just in case it's dropping packets, but leave on the
> masq stuff.
>
Firewalling is already off, running 'policy ACCEPT' on all chains. For one
experiment I did add a '-j LOG' target to the forward chain, simply to see
if traffic was moving from/to the right place. It was, but the packet count
on eth1 wasn't rising as it should have.

> What's the routing table on the RH8.0 box ? It should include a reference to
> the fact that either 192.168.1.254 is the default gateway OR that the
> 192.168.2.x subnet is reachable via 192.168.1.254
>
I don't have a copy here, but it had a correct default gateway.

> tcpdump might give you some clues as to why packets are getting dropped, you
> should be able to see tcpdump decode the ICMP errors, or perhaps even ARP
> queries.
>
I've never played with tcpdump, yet. Sounds like I need to.

Dale Pontius

In article <(E-Mail Removed)>,
Peter Matulis <(E-Mail Removed)> writes:
> On Mon, 05 Jan 2004 04:42:55 GMT, (E-Mail Removed)lid (Dale Pontius)
> wrote:
>
>>Desired Topology:
>>
>>Internet---Cable Modem---Netgear FR114P 192.168.2.1
>> |
>>192.168.2.0/255.255.255.0 |
>> |
>> eth1 - dhcp (192.168.2.33-63)
>> RedHat 7.2
>> eth0 192.168.1.254
>> |
>>192.168.1.0/255.255.255.0 Hub
>> |
>> |--RedHat 8.0 192.168.1.1
>> |--etc
>>
>>The Netgear box acts as DHCP server for 192.168.2.0
>>The RedHat 7.2 box acts as DHCP server for 192.168.1.0
>>
>>I bought the Netgear box last June. Before that the RedHat 7.2 box was
>>connected directly to the cable modem, with IP Masq. When I bought the
>>Netgear box, I quit allowing any incoming connections. Now I'd like to
>>make some select openings, but first want the RedHat 7.2 box between any
>>open ports an my LAN. At the moment, there is no firewalling in the
>>RH7.2 box. (That will change in the future, before I open any ports.)
>>
>>I've set /proc/sys/net/ipv4/ip_forward to "1"
>>The ip tables are all set to default policy ACCEPT.
>>
>>It doesn't route.
>>Packets get from the RedHat 7.2 box to my LAN or to the Internet.
>>Packets from the RedHat 8.0 box get to the RedHat 7.2 box.
>>Packets from the RedHat 8.0 box do not get to the Internet.
>>
>>Here's the answer to your next question:
>>
>>[root@tomcat log]# netstat -Nr
>>Kernel IP routing table
>>Destination Gateway Genmask Flags MSS Window irtt Iface
>>192.168.1.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0
>>192.168.2.0 0.0.0.0 255.255.255.0 U 0 0 0 eth1
>>127.0.0.0 0.0.0.0 255.0.0.0 U 0 0 0 lo
>>0.0.0.0 192.168.2.1 0.0.0.0 UG 0 0 0 eth1
>>
>>I tried a traceroute from the RH8.0 box while watching the adapters on
>>the RH7.2 box with ifconfig. Packets were coming in on eth0, but
>>nothing was leaving on eth1.
>>
>>I added a -j LOG rule to the FORWARD chain, and was able to see packets
>>coming in from the correct IP on eth0, and getting sent to eth1.
>>
>>But no forwarded packets come out of eth1.
>>
>>I thought that perhaps the problem is that both subnets are in the
>>RFC1918 allocation, and aren't supposed to be routed. But then I
>>searched /proc for some sort of rfc1918 switch, to no avail.
>
> You just can't route them on the internet.
>
I wondered if in its quest to be RFC compiliant, Linux might by default
not route those addresses. That's why I went looking for a switch, or
something in various documentation sources.

> Question: Can 192.168.2.1 and 192.168.1.1 ping each other?

192.168.2.1 is the Netgear router. Now that you mention it, I remember
seeing a 'ping' on one of the web pages. I'll have to see about trying
that one.
I didn't try a ping, but 192.168.1.1 is not able to connect to the web
pages on 192.168.2.1. Nor did I mention the presence of a second system
on the 192.168.2.0 net. (one Netgear, two computers) I was not able to
ssh from 192.168.1.1 to 192.168.2.34. I didn't check the vice versa.

Doing these experiments takes down the whole LAN for the family, so it
may be a day or two before I can experiment further. School homework,
and all that.

Dale Pontius

In article <(E-Mail Removed)>,
(E-Mail Removed) (David Efflandt) writes:
> On Mon, 05 Jan 2004 04:42:55 GMT, Dale Pontius <(E-Mail Removed)> wrote:
>> Desired Topology:
>>
>> Internet---Cable Modem---Netgear FR114P 192.168.2.1
>> |
>> 192.168.2.0/255.255.255.0 |
>> |
>> eth1 - dhcp (192.168.2.33-63)
>> RedHat 7.2
>> eth0 192.168.1.254
>> |
>> 192.168.1.0/255.255.255.0 Hub
>> |
>> |--RedHat 8.0 192.168.1.1
>> |--etc
>>
>> The Netgear box acts as DHCP server for 192.168.2.0
>> The RedHat 7.2 box acts as DHCP server for 192.168.1.0
>>
>> I bought the Netgear box last June. Before that the RedHat 7.2 box was
>> connected directly to the cable modem, with IP Masq. When I bought the
>> Netgear box, I quit allowing any incoming connections. Now I'd like to
>> make some select openings, but first want the RedHat 7.2 box between any
>> open ports an my LAN. At the moment, there is no firewalling in the
>> RH7.2 box. (That will change in the future, before I open any ports.)
>>
>> I've set /proc/sys/net/ipv4/ip_forward to "1"
>> The ip tables are all set to default policy ACCEPT.
>>
>> It doesn't route.
>> Packets get from the RedHat 7.2 box to my LAN or to the Internet.
>> Packets from the RedHat 8.0 box get to the RedHat 7.2 box.
>> Packets from the RedHat 8.0 box do not get to the Internet.
>>
>> Here's the answer to your next question:
>>
>> [root@tomcat log]# netstat -Nr
>> Kernel IP routing table
>> Destination Gateway Genmask Flags MSS Window irtt Iface
>> 192.168.1.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0
>> 192.168.2.0 0.0.0.0 255.255.255.0 U 0 0 0 eth1
>> 127.0.0.0 0.0.0.0 255.0.0.0 U 0 0 0 lo
>> 0.0.0.0 192.168.2.1 0.0.0.0 UG 0 0 0 eth1
>>
>> I tried a traceroute from the RH8.0 box while watching the adapters on
>> the RH7.2 box with ifconfig. Packets were coming in on eth0, but
>> nothing was leaving on eth1.
>
> tcpdump on the 7.2 interfaces may reveal more than traceroute, like that
> the Netgear is ignoring any LAN IPs not on its 192.168.2.0/24 LAN, hence
> no 192.168.1.0/24 packets being passed towards it.
>
By watching ifconfig, I saw packets coming in on eth0, and not going out
on eth1. When I get a chance, I'll try tcpdump, also.

>> I added a -j LOG rule to the FORWARD chain, and was able to see packets
>> coming in from the correct IP on eth0, and getting sent to eth1.
>>
>> But no forwarded packets come out of eth1.
>>
>> Any suggestions as to what I try next?
>
> Does the Netgear FR114P have configurable LAN routing (gateway for
> 192.168.1.0/24 network)? If not then the RH 7.2 box has to masquerade its
> eth0 network as its eth1 IP.
>
You may have hit a real snag, even after I get my RH72 box routing. I'll
cross that bridge when I come to it. I see two ways out, one quick and
dirty, the other clean, but more complex.
quick&dirty: router: 192.168.1.0/24
subnet1: 192.168.1.128/25
subnet2: 192.168.1.0/25
The linux boxen think they're on adjacent /25 subnets, the router on the
encompassing /24 subnet. I *think* this would work, though the subnet
adjacent to the router would have to not be DHCP from the router, else
it would hand out the /24 subnet mask instead of /25.
clean&complex: Set up the above, only use bridging.

Doing these experiments takes down the whole LAN for the family, so it
may be a day or two before I can experiment further. School homework,
and all that.

Dale Pontius

On Tue, 06 Jan 2004 05:21:29 GMT, (E-Mail Removed)lid (Dale Pontius)
wrote:

>In article <(E-Mail Removed)>,
> Peter Matulis <(E-Mail Removed)> writes:
>> On Mon, 05 Jan 2004 04:42:55 GMT, (E-Mail Removed)lid (Dale Pontius)
>> wrote:
>>
>>>Desired Topology:
>>>
>>>Internet---Cable Modem---Netgear FR114P 192.168.2.1
>>> |
>>>192.168.2.0/255.255.255.0 |
>>> |
>>> eth1 - dhcp (192.168.2.33-63)
>>> RedHat 7.2
>>> eth0 192.168.1.254
>>> |
>>>192.168.1.0/255.255.255.0 Hub
>>> |
>>> |--RedHat 8.0 192.168.1.1
>>> |--etc

[...]

>> Question: Can 192.168.2.1 and 192.168.1.1 ping each other?
>
>192.168.2.1 is the Netgear router. Now that you mention it, I remember
>seeing a 'ping' on one of the web pages. I'll have to see about trying
>that one.

Forget web pages. Simply have these two hosts attempt to ping each
other using a command line interface.

[...]

>Doing these experiments takes down the whole LAN for the family, so it
>may be a day or two before I can experiment further. School homework,
>and all that.

Why should a ping take down the lan?

If nothing works then provide the output to

$ ifconfig eth0 (eth1, etc)
$ netstat -rn

for all relevant hosts.

-----------------------------

"Purity of heart is to will one thing."
-- Soren Kierkegaard

Peter Matulis wrote:
> On Tue, 06 Jan 2004 05:21:29 GMT, (E-Mail Removed)lid (Dale Pontius)
> wrote:
>
>
>>In article <(E-Mail Removed)>,
>> Peter Matulis <(E-Mail Removed)> writes:
>>
>>>On Mon, 05 Jan 2004 04:42:55 GMT, (E-Mail Removed)lid (Dale Pontius)
>>>wrote:
>>>
>>>
>>>>Desired Topology:
>>>>
>>>>Internet---Cable Modem---Netgear FR114P 192.168.2.1
>>>> |
>>>>192.168.2.0/255.255.255.0 |
>>>> |
>>>> eth1 - dhcp (192.168.2.33-63)
>>>> RedHat 7.2
>>>> eth0 192.168.1.254
>>>> |
>>>>192.168.1.0/255.255.255.0 Hub
>>>> |
>>>> |--RedHat 8.0 192.168.1.1
>>>> |--etc
>
>
> [...]
>
>
>>>Question: Can 192.168.2.1 and 192.168.1.1 ping each other?
>>
>>192.168.2.1 is the Netgear router. Now that you mention it, I remember
>>seeing a 'ping' on one of the web pages. I'll have to see about trying
>>that one.
>
>
> Forget web pages. Simply have these two hosts attempt to ping each
> other using a command line interface.
>
AFAIK, the Netgear doesn't have a command line. That's why I spoke of
using a web page, because it does have a web-based ping. But I forgot,
I also have a half-installed Gentoo box on the 192.160.2.0 subnet, and
I can ping from there.
> [...]
>
>
>>Doing these experiments takes down the whole LAN for the family, so it
>>may be a day or two before I can experiment further. School homework,
>>and all that.
>
>
> Why should a ping take down the lan?
>
A ping doesn't take down the LAN. It's all the change.
-Reconfigure the router from the 192.168.1.0 to the 192.168.2.0 subnet.
-Enable/configure DHCP on the router
-Reconfigure the current server to act as a router
-A little network replugging
-Reboot everyone to pick up new DHCP parameters. (I know, a reboot
shouldn't be needed, but gdm gets SO confused if the network changes
under it.)

Do the experiments

When the experiments fail, change it all back. Since neither current nor
future server has X installed, there's an intermediate boot so one
desktop can gain web access to reconfigure the router.

It's not that anything's that tough, it just takes a little time, and
these days schoolwork tends to keep the kids pressed pretty hard against
both desktop machines.
> If nothing works then provide the output to
>
> $ ifconfig eth0 (eth1, etc)
> $ netstat -rn
>
> for all relevant hosts.
>
Easy to do. I just haven't saved the output from anything but the
would-be router.

Thanks,
Dale Pontius

In article <(E-Mail Removed)>,
(E-Mail Removed)lid (Dale Pontius) writes:
> In article <(E-Mail Removed)>,
> (E-Mail Removed) (David Efflandt) writes:
>> On Mon, 05 Jan 2004 04:42:55 GMT, Dale Pontius <(E-Mail Removed)> wrote:
>>> Desired Topology:
>>>
>>> Internet---Cable Modem---Netgear FR114P 192.168.2.1
>>> |
>>> 192.168.2.0/255.255.255.0 |
>>> |
>>> eth1 - dhcp (192.168.2.33-63)
>>> RedHat 7.2
>>> eth0 192.168.1.254
>>> |
>>> 192.168.1.0/255.255.255.0 Hub
>>> |
>>> |--RedHat 8.0 192.168.1.1
>>> |--etc
>>>
[snip]
>>
>> tcpdump on the 7.2 interfaces may reveal more than traceroute, like that
>> the Netgear is ignoring any LAN IPs not on its 192.168.2.0/24 LAN, hence
>> no 192.168.1.0/24 packets being passed towards it.
>>
[snip]
>>
>> Does the Netgear FR114P have configurable LAN routing (gateway for
>> 192.168.1.0/24 network)? If not then the RH 7.2 box has to masquerade its
>> eth0 network as its eth1 IP.
>>
You've hit the real issue, here. My diagram was simplified, just a bit.
I have a second machine, destined to be a replacement server on the
192.168.2.0 subnet. Instead of trying to talk to the router, I focused
on communicating between the three computers, the dual-homed RH7.2, the
RH8.0 on the .1.0 subnet, and the half-installed Gentoo on the .2.0
subnet. With a teeny bit of routing work (path from .2.0 back to .1.0
on the RH7.2 machine) I was able to get full interoperability between
the three machines.

Nothing *through* the router. It ignores stuff outside its subnet. Now
I need to work on my recovery position(s), as left from the previous
post, below.

Thanks,
Dale Pontius
> You may have hit a real snag, even after I get my RH72 box routing. I'll
> cross that bridge when I come to it. I see two ways out, one quick and
> dirty, the other clean, but more complex.
> quick&dirty: router: 192.168.1.0/24
> subnet1: 192.168.1.128/25
> subnet2: 192.168.1.0/25
> The linux boxen think they're on adjacent /25 subnets, the router on the
> encompassing /24 subnet. I *think* this would work, though the subnet
> adjacent to the router would have to not be DHCP from the router, else
> it would hand out the /24 subnet mask instead of /25.
> clean&complex: Set up the above, only use bridging.
>
> Doing these experiments takes down the whole LAN for the family, so it
> may be a day or two before I can experiment further. School homework,
> and all that.
>
> Dale Pontius

--