Re: Network Manager for embedded Linux

[Dan Williams <dcbw redhat com>]

On Thu, 2008-06-05 at 20:21 -0700, Nitin Mahajan wrote:
> Hello Dan,
> 
> --- On Thu, 5/6/08, Dan Williams <dcbw redhat com> wrote:
> 
> > From: Dan Williams <dcbw redhat com>
> > Subject: Re: Network Manager for embedded Linux
> > To: nitinm76 yahoo com
> > Cc: networkmanager-list gnome org
> > Date: Thursday, 5 June, 2008, 11:10 PM
> > On Thu, 2008-06-05 at 00:13 -0700, Nitin Mahajan wrote:
> > > HI!
> > > 
> > > I am planning to build and test the Network Manager
> > 0.6.5 for embedded Linux for a MIPS based CPU.
> > 
> > Any particular reason you wouldn't use 0.7? 
> 
> There is no specific reason to use 0.6.5, its just that I found it to be the latest release. If you suggest that 0.7 would be more suitable for embedded system, then I will try 0.7 instead.

I think 0.7 would be the better choice going forward since you'd have a
lot more control over the network configuration (if you need it).

>  0.7 is a
> > lot more flexible
> > and probably more suited for embedded systems where you
> > likely want more
> > control over the network configuration.
> > 
> > Also, are you planning on just using the NM daemon, or do
> > you want to
> > use the GNOME applet too?
> 
> I just want to use the NM daemon, assuming that it would be enough of automatic network configuration. I would be using it on a single user embedded Linux device, no use case of multiuser. In this case, still do I need the gnome applet? More over I would not have Gnome environment on the device nor I would have GTK.

Nope, you can just use the NM daemon.  You shouldn't need GTK or GNOME.
NM has the ability to grab connections from the system settings service
(nm-system-settings) as well as user connections (normally nm-applet on
GNOME or knetworkmanager on KDE).  Since you're not using GNOME or KDE,
you can just use system connections instead.

> But I would like to have the authentication mechanism for the wireless, atleast WEP and WPA to begin with.
> With this use case scenario, can you please tell me if I can use the Network Manager and by excluding and including which components in configuration? Do I also need some kind of Keyring Manager? Which one would be suitable if I don't have Gnome?

You can just use system connections with the keyfile plugin for the
system settings service.  You shouldn't need a keyring at all.  Were you
planning on allowing the user to configure the connections, or just to
select between preconfigured connections, or just have everything be as
automatic as possible?

NM will spawn nm-system-settings via dbus service activation, and
nm-system-settings will look for connections, read them in, and send
them to NetworkManager.  NM can then bring those connections up or take
them down based on network conditions.

You'll create a /etc/nm-system-settings.conf file that contains:

[main]
plugins=keyfile

this causes nm-system-settings to load the keyfile plugin, which looks
for connections in /etc/NetworkManager/system-connections.  Each file in
that directory is a .ini-style file describing the connection.  When you
get to that point, we can post some examples of keyfile connections for
you.  The connection files would contain the WPA or WEP key for
connection to your network.

> > 
> > > Can anyone give me some inputs about configuration and
> > dependencies when trying to do so? What do I specify for
> > --with-distro in configuration?
> > 
> > You could create your own distro target.  It mainly affects
> > what backend
> > is used for some IP configuration (see src/backends/*) and
> > not much
> > else.  On 0.7 the distro-specific backends are pretty much
> > empty because
> > we've been able to generalize most of it, so you
> > wouldn't have to do
> > much work on 0.7.
> > 
> > If you're just using NetworkManager, then you'll
> > need bits like libnl,
> > glib2, and dbus-glib.  The configure script will tell you
> > if you're
> > missing anything.  I could go into more details about the
> > dependencies,
> > but that would depend on whether you'd like to use
> > 0.6.6 or 0.7-pre.
> > 
> 
> In a reply to my previous post someone pointed out that I would also need a cryptographic library. Can I avoid the functionality that needs the cryptographic libraries, to begin with. I do have OpenSSL on my device but dont have GNU TLS or Mozillaa NSS. Did you guys find GNU TLS and Mozialla NSS to be better than OpenSSL?

The crypto libraries are used for reading certificates and private keys
for connections to 802.1x/802.11i networks.  If you don't need that
functionality you could safely comment out that code in NM.  It does
look like OpenSSL has the functionality required, but there's no code
for that yet.  I can write that if you'd like (or you could too :).

The one caveat with OpenSSL is that it's not GPL-compatible; which means
that you can't link OpenSSL with NetworkManager and distribute the
result outside your company.  If you're just using NM linked with
OpenSSL _inside_ your company, that's fine.  You just couldn't
distribute/sell/whatever the combination due to the license
incompatibility.

Dan


> Thanks for all your valuable inputs,
> 
> regards
> 
> -Nitin
> 
> 
> 
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