dhcpd handing out wrong gateway
Simon Hobson
dhcp1 at thehobsons.co.uk
Fri Sep 9 07:12:28 UTC 2011
Fredrik Björk wrote:
>I'm not actually asking for help to debug config files
Actually, yes you are, but you just don't realise it !
The DHCP server is normally quite reliable and
handing out the wrong options isn't something it
normally does - unless wrongly configured. And
now I see your config, I spot immediately that my
hunch was correct.
You have declared some host configs inside a
shared-subnet declaration. Except under very
limited circumstances which require you to
**really really** know what you're doing, never
ever do this. Host declarations are global in
scope, so options defined there will override
options inherited from a subnet.
So, say host "special" gets connected to a
different network. It will be given an IP address
from that new network but it will also inherit
the options declared in it's host declaration.
Bingo - you've now got a host with an IP address
correct for it's network, but the wrong gateway
address.
>shared-network BSR3CPE {
> subnet 123.123.230.0 netmask 255.255.255.0 {
> option routers 123.123.230.1;
> pool {
> range 123.123.230.40 123.123.230.254;
> deny members of "16-6M-DHCP";
> deny members of "Static00223a4e8017";
> }
> pool {
> range 123.123.230.2 123.123.230.39;
> allow members of "16-6M-DHCP";
> }
> }
> subnet 123.123.233.0 netmask 255.255.255.0 {
> option routers 123.123.233.1;
> max-lease-time 600;
> default-lease-time 600;
> pool {
> range 123.123.233.65 123.123.233.254;
> }
># The below "SpecialX" were handed out to people
>who experienced the "gateway problem". Separate
>host declarations solved their problems!
>host special {
>hardware ethernet 00:19:99:a0:51:13;
>option routers 123.123.233.1;
>fixed-address 123.123.233.33;
>}
>host special2 {
>hardware ethernet 00:21:91:ed:b3:bb;
>option routers 123.123.233.1;
>fixed-address 123.123.233.34;
>}
>host special3 {
>hardware ethernet 00:25:9c:34:fc:55;
>option routers 123.123.233.1;
>fixed-address 123.123.233.35;
>}
>host special4 {
>hardware ethernet 00:11:22:33:ef:ef:ef; # Dummy. For future use...
>option routers 123.123.233.1;
>fixed-address 123.123.233.36;
>}
> }
> subnet 123.123.231.0 netmask 255.255.255.0 {
> option routers 123.123.231.1;
> pool {
> deny members of "Static001e6bec1635";
> deny members of "Static00223a4e8017";
> range 123.123.231.13 123.123.231.254;
> }
> pool { allow members of
>"Static001e6bec1635"; range 123.123.231.8
>123.123.231.8; }
> pool { allow members of
>"Static00223a4e8017"; range 123.123.231.9
>123.123.231.9; }
> pool {
> allow members of "Static0018c022a3be";
> range 123.123.231.10 123.123.231.10;
> }
> }
>}
>
>
>shared-network CASACPE {
> subnet 123.123.235.0 netmask 255.255.255.0 {
> option routers 123.123.235.1;
> include "/etc/dhcpd.static235";
> pool {
> max-lease-time 600;
> default-lease-time 600;
> allow members of "MTA";
> range 123.123.235.250 123.123.235.254;
> }
> pool {
> max-lease-time 600;
> default-lease-time 600;
> allow unknown clients;
> range 123.123.235.240 123.123.235.249;
> }
> }
> subnet 123.123.237.0 netmask 255.255.255.0 {
> option routers 123.123.237.1;
> pool {
> max-lease-time 1200;
> default-lease-time 1200;
> deny members of "MTA";
> deny unknown-clients;
> range 123.123.237.2 123.123.237.254;
> }
> }
> subnet 123.123.238.0 netmask 255.255.255.0 {
> option routers 123.123.238.1;
> pool {
> max-lease-time 1200;
> default-lease-time 1200;
> allow members of "MTA";
> range 123.123.238.2 123.123.238.254;
> }
> }
>}
>
>
--
Simon Hobson
Visit http://www.magpiesnestpublishing.co.uk/ for books by acclaimed
author Gladys Hobson. Novels - poetry - short stories - ideal as
Christmas stocking fillers. Some available as e-books.
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