Difference between an ethernet modem and an ethernet router?

[nry]

From what I can gather, the modem would have the 'same IP' as the PC it's connected to, whereas a router has a public facing IP and a private facing IP and does some kind of nat'ing to handle the communication between the LAN and the outside world?

I think this is the last hurdle before i finally sign up for broadband!

nry

[Icarus]

Your right on the assumption. A modem is designed for single system use, where a router usually can connect about 4 or more PCs.

The modem only handles traffic to and from a single PC and a router has built in NAT (IPMasquerade for us Linux people ;)) where multiple machines can use the same external IP. It is then 'routed' to the appropiate system.

New routers also include built in firewalls

[nry]

Makes sense. The reason I ask is because the ISP I've chosen to use for broadband has 2 static IP options. I can either have 1 static IP or a block of 4. With the 4-block option I basically get:

1 public router IP
1 private router IP
1 'PC' IP
1 broadcast IP

If I want Linux to handle my connection eg firewall, masqeurading etc, I'm curious if I'm better off with an ethernet modem and 1 static IP or a router and 4 static IP's. There is no cost difference. I want to run at least a web server from home.

nry

[Jo.Mo.]

just get the router, then your not limited to only 1 computer, my service charges 5$ for every additional PC i want to put on when i'm just using my switch. Routers offer more flexibilty as well, plus the firewall. i've got my server running from the Router's "Virtual Server", it works pretty decent for a router that only cost me 40$ on tigerdirect.com

[Gertrude]

You are still going to need a modem no matter what you do, If you want a router the router will just plug into the modem.

[retoon]

Get yourself a decent router/switch combination (Its what these people are calling a router). They're about $60.00 here for a decent one. Now, your pc will need an ethernet adapter, and your external modem (either dsl or cable) will plug either directly into that ethernet port on your pc, or if you want to share the connection, then plug the pcs into any of the four ethernet ports on the router/switch, and plug the cable/dsl modem into the designated WAN/Internet/Cable/DSL ethernet port on the router.

[nry]

In response to my posting, I should have said I am aware a router also needs a modem and I'd be looking at a router/modem combo though I can go for the one supplied by the ISP I'm planning on using. I'll only be connecting the router or modem to the Linux PC and then using the 2nd NIC on Linux to connect to my LAN and using ip masq/iptables for a firewall etc. I don't want the router or modem to do anything other than give me a connection: Linux can handle all the rest otherwise I needn't have put my Linux machine together! My Linux PC is currently sharing it's dialup connection via ppp/dial on demand and is firewalled using iptables so it shouldn't (famous last words!) be too much of a step to do the same with broadband....

Cheers for the replies, I'm currently thinking router and the 4 IP option as it seems a more flexible option. The ISP has no issues with home LAN's or web servers from home. I can register a .co.uk domain with their service and they're happy to point my domain to my home server IP as opposed to my membership webspace which is cool...

nry