[LARTC] simple router

[LARTC] simple router

[Jeremiah Savage]

Hello,

I am attempting to construct a (simple?) router based
on Linux 2.4 with iproute2.

I have 3 ethernet cards on the router, with eth0
connected to a host,eth1 connected to a server and
eth2 connected to another computer.



                      xx.yy.88.101
                       +--------+
                       |        |
                       |  host  |
                       +---+----+
                           |
         xx.yy.zz.aa       |
             |             |eth0 - xx.yy.88.100
             |             |
+---------+  |      +----------------+
|another  | eth2    |                |
|computer +---------+  router        |
|         |         |                |
+---------+         +-------+--------+
xx.yy.zz.ab                 |
                            | eth1 - xx.zz.110.145
                            |
                        +---+-----+
                        |         |
                        | server  |xx.zz.110.148
                        |         |
                        +---------+

I am simply trying to get traffic through eth0 to eth1
so it can get to the server and get back out, but so
far I can't ping the server through the router,
although the router itself is capable of pinging the
server (so the link eth1 is active). And I've verified
that eth0 is also active as the router and the host
can ping each other.

So how do I get the router to pass traffic through to
the server?

I've tried
    # ip route add to unicast xx.zz.110.148 dev eth1
    RTNETLINK answers: File exists

and yet the host still can't ping the server.

And I've tried making eth0 "promiscuous"
        # ifconfig eth0 promisc
but that doesn't help either.


Anyone know the magic incantation that I need?

-- 
Jeremiah

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Re: [LARTC] simple router

[Jing Shen]

What's the routing table  in host and server  looks like ?
if there is only one connection on both of them , the routing table in
host only need one entry as :  0.0.0.0/0 -> xx.yy.88.100
and server need : 0.0.0.0/0 ->xx.zz.110.145

You don't need to add host route explicitly in the router becasue
the subnet on network interface is included in routing table by default.

Another indication is  "have you enabled iptable on router to block connection
between
different subnet?"

James Shen


> Hello,
>
> I am attempting to construct a (simple?) router based
> on Linux 2.4 with iproute2.
>
> I have 3 ethernet cards on the router, with eth0
> connected to a host,eth1 connected to a server and
> eth2 connected to another computer.
>
>                       xx.yy.88.101
>                        +--------+
>                        |        |
>                        |  host  |
>                        +---+----+
>                            |
>          xx.yy.zz.aa       |
>              |             |eth0 - xx.yy.88.100
>              |             |
> +---------+  |      +----------------+
> |another  | eth2    |                |
> |computer +---------+  router        |
> |         |         |                |
> +---------+         +-------+--------+
> xx.yy.zz.ab                 |
>                             | eth1 - xx.zz.110.145
>                             |
>                         +---+-----+
>                         |         |
>                         | server  |xx.zz.110.148
>                         |         |
>                         +---------+
>
> I am simply trying to get traffic through eth0 to eth1
> so it can get to the server and get back out, but so
> far I can't ping the server through the router,
> although the router itself is capable of pinging the
> server (so the link eth1 is active). And I've verified
> that eth0 is also active as the router and the host
> can ping each other.
>
> So how do I get the router to pass traffic through to
> the server?
>
> I've tried
>     # ip route add to unicast xx.zz.110.148 dev eth1
>     RTNETLINK answers: File exists
>
> and yet the host still can't ping the server.
>
> And I've tried making eth0 "promiscuous"
>         # ifconfig eth0 promisc
> but that doesn't help either.
>
> Anyone know the magic incantation that I need?
>
> --
> Jeremiah
>
> __________________________________________________
> Do You Yahoo!?
> Get personalized email addresses from Yahoo! Mail
> http://personal.mail.yahoo.com/
>
> _______________________________________________
> LARTC mailing list / LARTC@mailman.ds9a.nl
> http://mailman.ds9a.nl/mailman/listinfo/lartc HOWTO: http://ds9a.nl/2.4Routing/


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Re: [LARTC] simple router

[Jeremiah Savage]

Turns out that /proc/sys/net/ipv4/ip_forward was set
to 0, as /etc/network/options had "ip_forward=no" (a
debian thing). Enabling this option got the router
working.

-- 
Jeremiah

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