If you have synaptic installed, go through the list of available packages, network-manager should be in there as well as front ends for it depending on which desktop environment you have installed, ex. (network-manager-gnome). Personaly, I never install the front end, just network-manager. But highlight it in synaptic and read what it all does, you may want to install it, then again, maybe not as I just read it and.... well, you'll see.
Or, you can just read the readme.debian I've posted below, I'm not sure if the file /etc/network/interfaces exist without network-manager being installed, probably is. Not sure if this will do the trick for you, it's just a suggestion.
Code:
NetworkManager consists of two parts: one is on the system level daemon that
manages the connections and gathers information about new networks. The other
is a systray applet that users can use to interact with the NetworkManager
daemon.
Security
~~~~~~~~
To allow users to connect to the NetworkManager daemon they have to be in the
group "netdev". If you want to add a user to group "netdev" use the command
"adduser username netdev" or one of the graphical user management frontends.
After that you have to reload D-Bus with the command "/etc/init.d/dbus reload".
Configuration of wireless and ethernet interfaces
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Only devices that are *not* listed in /etc/network/interfaces or which have
been configured "auto" and "dhcp" (with no other options) are managed by NM.
This way you can setup a custom (static) configuration for a device and NM
will not try to override this setting.
After modifying /etc/network/interfaces you have to restart NM with the
command "/etc/dbus-1/event.d/25NetworkManager restart".
Examples:
1.)
auto wlan0
iface wlan0 inet dhcp
-> This device is managed by NM.
1.a)
allow-hotplug eth0
iface eth0 inet dhcp
-> This device is managed by NM
2.)
auto wlan0
iface wlan0 inet dhcp
wpa-conf /etc/wpa_supplicant/wpa_supplicant.conf
-> This devices is *not* managed by NM because it has additional options.
3.)
iface wlan0 inet dhcp
-> This device is *not* managed by NM because it is not set to "auto".
4.)
iface eth0 inet static
address 192.168.1.10
netmask 255.255.255.0
gateway 192.168.1.1
-> This device is *not* managed by NM because it is configured as "static" and
has additional options.
5.)
Device is not listed in /etc/network/interfaces.
-> Device is managed by NM.
Dial-up configuration
~~~~~~~~~~~~~~~~~~~~~
After configuring your PPP interface (either manually or by using a tool like
"pppconfig") to work with a peer called "myisp" you should edit
/etc/network/interfaces and add a stanza like this:
iface ppp0 inet ppp
provider myisp
NM will then make it possible to dial this connection.
If you want to set up multiple internet service providers simply create a new
stanza as listed above specifying the provider and a different iface, e.g. ppp1.
After modifying /etc/network/interfaces you have to restart NM with the
command "/etc/dbus-1/event.d/25NetworkManager restart".
Please read the "Debian Reference Manual", section 10.6.1.4 or the "interfaces"
man page for further information.
