My network is operated by Cisco Catalyst with several VLANs and one DHCP server. On the Catalyst, for each vlan is set ip address-helper
with the IP of DHCP server. isc-dhcp-server on ubuntu 14.04 is used as DHCP server.
I have several network subnets set as can be seen below and all of them work without problem except one and I cant figure out why.
The network which does not work properly is 10.12.35.0/24 The messages I got from syslog are like:
Jan 6 06:57:54 dhcp-server-1 dhcpd: DHCPDISCOVER from 00:0c:29:33:3c:bb via 10.12.35.1: unknown network segment
And as I already mentioned – all other subnets work well
Thanks! I really appreciate your help!
config file:
option ntp-servers 0.pool.ntp.org, 1.pool.ntp.org, 2.pool.ntp.org;
authoritative;
allow client-updates;
allow unknown-clients;
ddns-updates on;
ddns-domainname "domain.do";
key rndc-key {
secret notgonnatellyou;
algorithm hmac-md5;
}
ddns-update-style interim;
option domain-name "domain.do";
option domain-name-servers 10.12.240.29, 10.12.32.41;
default-lease-time 600;
max-lease-time 7200;
log-facility local7;
subnet 10.12.4.0 netmask 255.255.252.0 {
option domain-name-servers 8.8.8.8;
option routers 10.12.4.1;
option subnet-mask 255.255.252.0;
option broadcast-address 10.12.7.255;
pool {
range 10.12.4.100 10.12.5.250;
}
}
subnet 10.12.35.0 netmask 255.255.255.0 {
ddns-updates off;
option routers 10.12.35.1;
option subnet-mask 255.255.255.0;
option broadcast-address 10.12.35.255;
pool {
range 10.12.35.100 10.12.35.254;
}
}
subnet 10.12.96.0 netmask 255.255.255.0 {
option routers 10.12.96.1;
option subnet-mask 255.255.255.0;
option broadcast-address 10.12.96.255;
pool {
range 10.12.96.100 10.12.96.200;
}
}
subnet 10.12.32.0 netmask 255.255.255.0 {
option routers 10.12.32.1;
option subnet-mask 255.255.255.0;
option broadcast-address 10.12.32.255;
pool {
range 10.12.32.200 10.12.32.220;
}
}
subnet 10.12.0.0 netmask 255.255.252.0 {
option routers 10.12.0.1;
option subnet-mask 255.255.252.0;
option broadcast-address 10.12.3.255;
pool {
range 10.12.0.10 10.12.2.255;
}
host some-host {
hardware ethernet 00:0c:29:52:1c:a7;
fixed-address 10.12.3.0;
}
host someother-host {
hardware ethernet 00:50:56:9f:04:26;
fixed-address 10.12.3.1;
}
host evenother-host {
hardware ethernet 10:dd:b1:e7:b2:e0;
fixed-address 10.12.0.200;
}
}
zone domain.do. {
primary 10.12.240.29;
key rndc-key;
}
zone 12.10.in-addr.arpa. {
primary 10.12.240.29;
key rndc-key;
}
Best Answer
The configuration was OK all along. The problem was with "ghost process". I dont know how that happened, but I ran two dhcpd processes and the first one was really old... from the time when the subnet was not defined in conf