SOLVED Re: weird: default router not assigned, lease not written, single host

MAtteo HCE Valsasna valsasna at uninsubria.it
Fri Oct 27 10:57:26 UTC 2006


> From: Bruce Hudson <Bruce.Hudson at Dal.Ca>
> Subject: Re: weird: default router not assigned, lease not written, single host
> Date: Thu, 26 Oct 2006 09:23:13 -0300 (ADT)
> 
>  
> > I have a strange problem with a single host on a single subnet, to which
> > the DHCP server assigns an IP addres but not the default router option.
> > 
> > I have verified by sniffing that the host does does request the default
> > router option in DHCPDISCOVER and DHCPREQUEST - see trace below
> > 
> > In addition, the address assignation is written to the logfile, but the
> > lease stanza is NOT written do dhcpd.leases, and it does NOT exist even
> > according to omapish.
> > 
> > the problem il limited to one mac-address on one subnet:
> > * the host is dual-boot, same problem with windows and linux
> > * assigning the same mac address to another host on the same subnet
> > leads to the same behaviour.
> > * assigning the same mac address to another host on another subnet leads
> > to normal behaviour (i.e., default router assigned and lease written).
> > 
> 
>     You do not provide a copy of your DHCP configuration so I am making
> a guess here but the symptoms you describe would be explained if (1) there
> is a fixed-ip host stanza in the config for the MAC address in question
> and (2) you specify the routers in the pool configuration. Fixed IP hosts
> are not leases so they are not recorded. Even if the address in question 
> is listed in a pool, it is not taken from the pool so any paramters in
> the pool stanza are ignored.

your guess was correct:

host simone_128 { hardware ethernet 00:13:d4:a6:a1:17; fixed-address <client_subnet>.196; }

  subnet <client_subnet>.192 netmask 255.255.255.192 {
    pool {
      range <client_subnet>.208 <client_subnet>.250;
      option broadcast-address <client_subnet>.255;
      option routers <client_subnet>.254;
      option subnet-mask 255.255.255.192;
    }
  }

the host stanza was in a separate, dynamically generated file I didn't
even remember about (we did check for any configuration specific to that
mac address, but not in the right file).

after moving the options out of the pool stanza, the server handed out
them as expected:

  subnet <client_subnet>.192 netmask 255.255.255.192 {
    pool {
      range <client_subnet>.208 <client_subnet>.250;
    }
    option broadcast-address <client_subnet>.255;
    option routers <client_subnet>.254;
    option subnet-mask 255.255.255.192;
  }

Bootstrap Protocol
    Message type: Boot Reply (2)
    Hardware type: Ethernet
    Hardware address length: 6
    Hops: 1
    Transaction ID: 0xf7d9e807
    Seconds elapsed: 0
    Bootp flags: 0x0000 (Unicast)
        0... .... .... .... = Broadcast flag: Unicast
        .000 0000 0000 0000 = Reserved flags: 0x0000
    Client IP address: 0.0.0.0 (0.0.0.0)
    Your (client) IP address: <client_subnet>.196 (<client_subnet>.196)
    Next server IP address: 0.0.0.0 (0.0.0.0)
    Relay agent IP address: <client_subnet>.254 (<client_subnet>.254)
    Client hardware address: 00:13:d4:a6:a1:17
    Server host name not given
    Boot file name not given
    Magic cookie: (OK)
    Option 53: DHCP Message Type = DHCP Offer
    Option 54: Server Identifier = <server_subnet>.2
    Option 51: IP Address Lease Time = 1 day
    Option 1: Subnet Mask = 255.255.255.192
    Option 15: Domain Name = "uninsubria.it"
    Option 3: Router = <client_subnet>.254			***
    Option 6: Domain Name Server
        IP Address: <server_subnet>.2
        IP Address: <server_subnet>.130
    Option 82: Agent Information Option (12 bytes)
        Agent Circuit ID (2 bytes)
        Agent Remote ID (6 bytes)
    End Option


thanks for your help

MAtteo 




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