Mailinglist Archive: opensuse (3138 mails)

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Re: [SLE] routing dhcpd problems
  • From: Darryl Gregorash <raven@xxxxxxxxxxxxx>
  • Date: Tue, 07 Dec 2004 15:47:23 -0600
  • Message-id: <41B624EB.6090205@xxxxxxxxxxxxx>
Ulrich Leopold wrote:

<snip>

Ok, this is the tabel I get:

Destination Gateway Genmask Flags Metric Ref Use
Iface
192.168.0.0 0.0.0.0 255.255.255.128 U 0 0 0
eth1
62.194.22.0 0.0.0.0 255.255.254.0 U 0 0 0
eth0
169.254.0.0 0.0.0.0 255.255.0.0 U 0 0 0
eth0
127.0.0.0 0.0.0.0 255.0.0.0 U 0 0 0
lo
0.0.0.0 62.194.22.1 0.0.0.0 UG 0 0 0
eth0

I am not sure but it seems that there are some things not correct which
might cause the trouble...? The route should be to eth0 (62.194.22.104).
eth1 (192.168.0.0) is another computer in the local network. 169.254.0.0
must be the name server of the ISP.

Unless something else shows up to be a problem, for now I agree with Anders and Ken that something is probably wrong with the forwarding or masquerading setup on your router. Everything here looks OK, except maybe for the first line (see below). The mask (255.255.254.0) in the second line -is- a little strange, but your ISP's DHCP server sent that, and we have to assume they know what they are doing (well,hope they do :) ).

Here is something on the other questions you asked here. ipv4 assignments are discussed in RFC 3330, see http://www.faqs.org/rfcs/rfc3330.html

Your default route is through eth0, that is what the bottom line means. The first line suggests you are only using IPs between 192.168.0.0 and 192.168.127 (plus 192.168.0.255, the broadcast address) in your local network. But if you have a 192.168.0.128, then according to this route table, traffic to it is going out eth0! Probably not what you want :) That mask should probably be 255.255.255.0, or even 255.255.0.0 (which is what RFC 3330 suggests to me).

Also from RFC 3330:

"169.254.0.0/16 - This is the "link local" block. It is allocated for
communication between hosts on a single link. Hosts obtain these
addresses by auto-configuration, such as when a DHCP server may not
be found."

The DHCP client may assign an IP in this range to eth0 if for any reason it cannot obtain/renew a lease from the ISP. Why that line even needs to be in your route table at all is a mystery to me; an IP in that range is only valid if your DHCP client cannot find a server, and until it does, only DHCP traffic is going out eth0 anyway. The only times a "link local" IP could possibly be part of a DHCP message are exactly the times when a DHCP client must *not* include an IP in its messages (RFC 2131).



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