I have a ADSL router that runs a dhcp server and my 4 linux boxes get their IP's from it.
Is it possible to have the router always give out the exact same IP to these boxes. If I turn off the router sometimes the IP's get switched. Can I put a static IP in the ifcfg-eth0 will that work?

oh and I can't do MAC level DHCP allocation with this router....doesn't support it.

Should I just go ahead and replace the router then?

My router is like that, if i wanna keep an IP i just hard code the ip on the machine.

My example:

I have the Linksys BFSR41 (the 4 port router). I have it set to give out IPs in the range of 192.168.1.100 to 192.168.1.103. Then on my linux box that i want to have a static IP, i just set the IP to 192.168.1.200 and put in my isps DNS servers and the router's IP for the gateway. Basically, dont use DHCP. If you have a good router you can turn off that functionality, although I've seen bad routers that still had that ability.

So basically turn off the DHCP client? and assume a static IP??

yep

are these internal IPs or are they world addressable (and if so, do you always have the same 4 provided)?

oh, mine are all internal, i only have 1 that is world addressable and its assigned via DHCP. I turned off the DHCP server on the internal side but the router runs a DHCP client on the external side so that i may get my ip address from my ISP, but then to mock a static ip, i signed up for dynmaic dns service. well its really a static hostname for a dynamic ip.

puzz_1: if you're in the same position as Robert0380 and the addresses you're using aren't world addressable (and hence the values are only important with respect to one another) you can just assign the IP address on each machine (typically in /etc/network/interfaces) rather than using DHCP. the router should rebuild its tables as it recieves data from each machine.
if you're given a bunch of world addressable IP addresses from the ADSL provider (and they change sometimes) then I can't think of a good solution.

to add to what 0x4B just said. If you are given 4 IPs that come in on 1 line
there are 2 options i think you could try:


1. Get a hub (not a router). They are cheaper but arent switched so
heavy traffic kills the quality of the connection.

2. Get a switch (again not a router). They cost more than hubs but are
switched so they are faster. I was planning on looking into this one day
but check to see if it is possible to use your DSL/Cable router as just a
run-of-the-mill switch and not a router. If you can do this....

a. set up each computer to obtain via dhcp (that is if the ips arent static)
b. hook everything up and let it run

If the dsl/cable router can act as an ordinary switch then it should be smart enough to route traffic correctly i think and any dhcp requests that the computers make should be sent out the WAN interface to your ISPs dhcp server. This setup puts every computer on the internet directly so make sure you have firewalls set up.

If your ISP doesnt allow you to use multiple IPs then ignore all of this.