DHCPDISCOVER & no DHCPOFFER received

Avatar · 05-16-2007, 09:37 AM

Hi this question is in regards to a Ubuntu server I am running.

This server is command line only, there is no GUI and no control panels, etc.

The server has 2 interfaces, eth1 which is connected to a 192.168.1.0 network and eth0 which is used to connect to a ADSL modem as ppp0.

All Internet connections on the LAN go throught the server from eth1 to ppp0.

Everything works fine except for this message in my syslog:

Code:

May 16 09:58:46 proxy dhclient: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 9
May 16 09:58:55 proxy dhclient: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 12
May 16 09:59:07 proxy dhclient: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 15
May 16 09:59:22 proxy dhclient: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 7
May 16 09:59:29 proxy dhclient: No DHCPOFFERS received.
May 16 09:59:29 proxy dhclient: No working leases in persistent database - sleeping.

From my limited understanding, eth0 does NOT need a dchp address. Where do I turn off it's trying to get a DHCP address, without screwing up my Internet access?

ifconfig:

Code:

eth0      Link encap:Ethernet  HWaddr 00:10:18:24:C9:4B
          inet6 addr: fe80::210:18ff:fe24:c94b/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:1076072 errors:9620 dropped:0 overruns:0 frame:0
          TX packets:988451 errors:0 dropped:0 overruns:0 carrier:0
          collisions:9620 txqueuelen:1000
          RX bytes:1017914034 (970.7 MiB)  TX bytes:194742708 (185.7 MiB)
          Interrupt:90

eth1      Link encap:Ethernet  HWaddr 00:14:5E:20:32:02
          inet addr:192.168.1.1  Bcast:192.168.1.255  Mask:255.255.255.0
          inet6 addr: fe80::214:5eff:fe20:3202/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:788566 errors:0 dropped:0 overruns:0 frame:0
          TX packets:1140618 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:173075779 (165.0 MiB)  TX bytes:1113591007 (1.0 GiB)
          Interrupt:177

lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:8537 errors:0 dropped:0 overruns:0 frame:0
          TX packets:8537 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:1663470 (1.5 MiB)  TX bytes:1663470 (1.5 MiB)

ppp0      Link encap:Point-to-Point Protocol
          inet addr:64.XXX.XXX.XXX  P-t-P:64.XXX.XXX.XXX  Mask:255.255.255.255
          UP POINTOPOINT RUNNING NOARP MULTICAST  MTU:1492  Metric:1
          RX packets:21395 errors:0 dropped:0 overruns:0 frame:0
          TX packets:19828 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:3
          RX bytes:18702176 (17.8 MiB)  TX bytes:2901039 (2.7 MiB)

tredegar · 05-16-2007, 11:29 AM

Please post your /etc/network/interfaces file.

Avatar · 05-16-2007, 11:50 AM

/etc/network/interfaces:

Code:

auto lo eth1

iface lo inet loopback

iface eth1 inet static
        address 192.168.1.1
        netmask 255.255.255.0
        network 192.168.1.0
        broadcast 192.168.1.255

auto eth0
iface eth0 inet dhcp

hm, if I remove dhcp from the last line, I guess that should work, but will I screw up my Internet access? (It needs to get a dhcp address when it connects to the ADSL modem.)

tredegar · 05-16-2007, 12:07 PM

Thank you.

Quote:

(It needs to get a dhcp address when it connects to the ADSL modem.)

Now you are confusing me. In your first post you said "eth0 does NOT need a dchp address."
... and your modem does not seem to be running a dhcp server because in your syslog it says "No DHCPOFFERS received."

Somehow your eth0 is getting an IPV6 address: inet6 addr: fe80::210:18ff:fe24:c94b/64 Scope:Link
Maybe that is set up with the ppp0 business ?

Can you be more exact about your setup / can someone else help?

Avatar · 05-16-2007, 12:44 PM

lol

I'm confusing you because I myself am confused.

What I mean is my eth0 is PHYSICALLY connected to an ADSL modem. When I type "pon" it connects to my DSL connection and a new interface ppp0 is created. My DSL provider assigns me a IP address for my connection from its DHCP server.

I do not know what this means for my eth0 interface, but it seems to be polling the 192.168.1.0 network for an address, I don't know why, it has already got one from the Internet Provider. Also, the interface eth1 provides DHCP addresses for all the computers on my network EXCEPT eth0, I don't know why it does this either.

So either eth0 needs a DHCP address from eth1, and isn't getting it, or it doesn't need one and is making a lot of noise for nothing. Either way, I need to get rid of this message.

I don't know about the ipv6 address. It's always been like that.

tredegar · 05-16-2007, 02:05 PM

Quote:

I'm confusing you because I myself am confused.

Aren't we all sometimes?

Quote:

When I type "pon" it connects to my DSL connection and a new interface ppp0 is created.

Then there's some pon script (about which I know nothing) that is run to connect your eth0 to the internet. Apparently it is happy with IPV6. So all well & good.

/etc/network/interfaces has no work to do for eth0 (because pon has already done the work), but it is currently trying to get an address with dhcp, which it doesn't need, and cannot be provided anyway because your modem isn't running a dhcp server.

Your options:

1] Ignore the error messages - they are harmless
2] Try commenting out the references to eth0 in your interfaces file (I think this will work for you)

Background: Your ISP is giving your modem an internet IP address. You are connecting to your modem with ppp. There is some IP masquerading / forwarding going on that allows your intranet LAN (192.168.1.*) to access the internet. It is working.

The last time I used ppp was when I has a USB DSL modem. It was a complete PITA, and I got myself a proper ADSL ethernet modem / router / switch / firewall (search through my previous posts for details). It saved me a load of configuration troubles.

I like to know what is going on with my networking configuration, and I mistrust the GUI ("idiot-proof") tools. So I have everything set up manually, and it is stable and functions well.

Hope this helps