Arch Linux

Rena

Member

From: Ontario

Registered: 2015-05-08

Posts: 13

Website

Addressing machines by hostname without reliable DHCP

I'm using a somewhat awkward LAN setup:

Both guilmon (main system) and gabumon (secondary system) are running Arch. I'm not able to run a cable, so I have to use DD-WRT to connect them via wifi. (I've tried just having them connect directly to the wifi instead of using a router, but the signal isn't strong enough.) The switch is used because the DD-WRT router has only 4 ports, and I have more than 4 machines to connect (guilmon, gabumon, and various game consoles not shown there); also, I found the router didn't like to work nicely with more than one port in use in client modes.

The trouble I'm having is with Bell's craptacular modem (and probably DD-WRT is not helping either). It simply doesn't seem to be able to manage DHCP. Both machines are able to connect to the Internet and are able to connect to eachother by IP, but not by name.

If I just let it assign DHCP addresses, it does so, but then hostname lookups fail:

 rena@guilmon~> host guilmon
Host guilmon not found: 3(NXDOMAIN)

If I assign guilmon and gabumon each a static IP, it sometimes handles that, but sometimes still gives them a different IP. I suspect this is because of something silly DD-WRT is doing. It seems to assume the hostname of one of the machines connected to it at random. That is, I've assigned each device its own IP:

• guilmon: 192.168.2.2

• dd-wrt: 192.168.2.3

• gabumon: 192.168.2.4

But sometimes guilmon or gabumon ends up assigned 192.168.2.3 instead.

I've tried poking at various settings with little success. (The Bell modem gives very little control over settings, and the DD-WRT web UI has stopped working; to fix it would require a factory reset which would wipe my settings which were quite a pain to get working.) I've thought about maybe just having a script on each machine, which tries to connect to ssh on various addresses and writes the successful ones to /etc/hosts, but surely there's a better solution?

branch

Member

Registered: 2014-03-16

Posts: 209

Re: Addressing machines by hostname without reliable DHCP

Avahi and mdns are for just this.  Let dhcp be dynamic, then enable avahi-daemon to announce the hostname and configured address over mdns. Enable mdns in /etc/nsswitch.conf and you should be able to access your hosts as guilmon.local, gabumon.local, etc.

pigiron

Member

From: USA

Registered: 2009-07-14

Posts: 150

Re: Addressing machines by hostname without reliable DHCP

Everyone's going to have their own opinion. Mine is that I (mostly) don't understand the need for using DHCP for a SOHO network. While I admittedly have both feet firmly implanted in old skool for sure, my thoughts are that it's just something else that can go wrong. And judging by some previous Linux forum flurries, I've avoided some angst when situations such as yours crop up. No offense intended to the other poster, but adding Avahi and mdns to the mix personally seems like an accident waiting to happen. Perhaps someone could enlighten me/us about the advantages that I don't see in such a setup.

Granted, my 20 or so systems have been gradually added to the network, but I don't find it difficult to simply setup each for a static connection when the time came. In fact, the most difficult part has been killing processes that systemd fires up that want to overwrite my settings after a fresh install. But I do admit that I had to Google around to find out how to setup a static connection on my Android phone, but once discovered, it's not all that difficult either. As for some of the other portable devices, Wicd (or even Network Manager... chuckle) handle the situation nicely.

Now, having said all that, I do keep a couple of DHCP IP addresses reserved for visitors, so when they bring their devices to my adobe they don't need to fiddle with their settings to connect to my guest network.

Anyway, my opinion is worth little about how you intend to proceed, but it at least provides another perspective.