how we can fix this isc-dhcp-server failed ?

rjdbarsal · 07-12-2013, 10:10 PM

Scenario:
I set up my ubuntu server as a router.
see diagram > https://fbcdn-sphotos-g-a.akamaihd.n...85323098_n.jpg

eth 0 - is connected from the internet and other network.
eth 1 - is an internal network that connect to my laboratory network

Manually configure ip address from the other unit (in the laboratory network e.g. PC1) same with the gateway of the server router (eth 1).

PC1 with:
address 192.168.1.2
netmask 255.255.255.0
gateway 192.168.1.2

server eth1 (internal network) in static with:
address 192.168.1.2
network 192.168.1.0
netmask 255.255.255.0
broadcast 192.168.1.255

The problem we encounter is that the other unit in the laboratory (PC2 , PC3) can't connect to internet but can access to other network.

How can we fix this?

Ser Olmy · 07-12-2013, 10:29 PM

Quote:

Originally Posted by rjdbarsal

PC1 with:
address 192.168.1.2
netmask 255.255.255.0
gateway 192.168.1.2

The PC is using itself as a gateway. That cannot possibly work.

Quote:

Originally Posted by rjdbarsal

server eth1 (internal network) in static with:
address 192.168.1.2
network 192.168.1.0
netmask 255.255.255.0
broadcast 192.168.1.255

The server is configured with the same IP address as the PC. Every host in a network must have a unique IP address.

rjdbarsal · 07-12-2013, 11:31 PM

Thanks for quick response.

I add a PC4 to the switch with window OS but it can connect to the Internet.
Theres is a problem here in Ubuntu OS.

note: PC2&PC3(ubuntu OS) and PC4(Windows) are all set to auto dhcp.
PC1 is manually configured. This is a security case also.

Ser Olmy · 07-12-2013, 11:51 PM

Assuming that the Ubuntu server has Internet access and is able to reach any other resources without issues, you will need to do the following to get your lab network online:

configure eth1 on the Ubuntu server with an IP address in a different subnet than the one eth0 is connected to
configure iptables on the Ubuntu server to perform NAT on outgoing traffic from the lab network
configure all lab PCs with static IP addresses, or (preferably) install and configure a DHCP service on the Ubuntu server

The lab PCs will be using the Ubuntu server as a gateway. They will need to use whatever DNS server the Ubuntu server is using (look in /etc/resolv.conf on the server for clues).

If you don't really know how IP routing works, you will need to look up some tutorials or HowTos, or get some assistance.