cannot save connection without specifying a gateway

[Istvan Szekeres]

I have a dedicated network adapter in my computer that is directly connected to my nas (no router/switch involved). Both have a dedicated IP address. When I want to set up the connection, it insists on specifying a gateway address. As the two are connected directly there is no gateway and it does not even makes sense. However without a gateway address specified the connection cannot be saved.

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: network-manager-gnome 0.9.3.995+git.20120313t141231.c89224f-0ubuntu2
ProcVersionSignature: Ubuntu 3.2.0-20.33-generic 3.2.12
Uname: Linux 3.2.0-20-generic x86_64
NonfreeKernelModules: nvidia
ApportVersion: 1.95-0ubuntu1
Architecture: amd64
CRDA: Error: command ['iw', 'reg', 'get'] failed with exit code 1: nl80211 not found.
Date: Fri Mar 30 19:41:51 2012
IfupdownConfig:
 auto lo
 iface lo inet loopback
InstallationMedia: Ubuntu 12.04 LTS "Precise Pangolin" - Beta amd64 (20120328)
NetworkManager.state:
 [main]
 NetworkingEnabled=true
 WirelessEnabled=true
 WWANEnabled=true
 WimaxEnabled=true
ProcEnviron:
 LANG=en_US.UTF-8
 SHELL=/bin/bash
RfKill:

SourcePackage: network-manager-applet
UpgradeStatus: No upgrade log present (probably fresh install)

[Mathieu Trudel-Lapierre (cyphermox)]

Indeed, confirming: the gateway is "correctly" marked as mandatory since it is for most connection setups.

As a workaround you may want to use "Link-local only" if both systems don't need to be using a specific IP address -- the IP will be defined automatically by avahi/zeroconf, and both systems should be reachable by name via the ".local" domain (as per avahi again, and M-DNS). For instance:

ssh pc1.local (from pc2)
ssh pc2.local (from pc1)

And both would have an IP address in the 169.254.0.0 range, selected randomly by the software on each system.

Otherwise you'll need to use a "dummy" gateway. If you really need to avoid having the gateway set as default and override wifi, for example; then you can check the "Use this connection only for the resources on its network" checkbox under Routes.

Since this was explicitly done as a conscious decision to avoid issues with users who may not have a strong knowledge of networking; I'll close this as Won't Fix. We can revisit and reopen as necessary and once discussion has been done with upstream.

[Istvan Szekeres (szekeres)]

I accept this decision but I completely disagree with it. Forbidding me entering a totally valid configuration for whatever reason but forcing me to enter an invalid one absolutely does not sound right to me.

Analyzing the use case also does not tell me this is a right solution. Those without strong knowledge of networking will most probably ask someone else what data to enter (how the heck could they figure it out themselves), so most probably they will be told the gateway address as well. So what this "feature" is protecting them is that when they enter the addresses they were told they simply forget one of them. I find it very unlikely. Also they could do a lot other mistakes there - entering wrong numbers, swapping the ip and the gw addresses, etc.

Also, what if they really do not have a gw address for that interface? There is absolutely no indication that that is the reason for the button to be disabled. It took me 10 minutes to figure it out. At least please enable the button and complain about the missing gw when it is pressed.

I could also accept that the gw is required for the _first_ interface, but not for additional ones (like in my case).

[Mathieu Trudel-Lapierre (cyphermox)]

That's reasonable, but please bring these concerns upstream on the NetworkManager mailing list [1]; at that point they can be addressed upstream, and we'll get any possible changes with the next release.

[1] http://mail.gnome.org/mailman/listinfo/networkmanager-list