I couldn't figure out how to make this entry post below Terran's entry.
Terrance, Thanks a million. I made the changes you suggested to my
interface file and my Ubuntu MATE 15.10 boxes now have rock solid
connections on both networks and simultaneous internet and file sharing
access.
I wanted to post the results on this thread for the benefit of others
whom cannot get 2 NICS working with one internet connection. I'll start
with a working interfaces file example.
This is the /etc/network/interfaces
file:
# interfaces(5) file used by ifup(8) and ifdown(8)
auto lo
iface lo inet loopback
# J5 Create USB/Ether Adapter MAC c4b
# Subnet Two Gateway 192.168.2.1
auto enx00051ba184cb
iface enx00051ba184cb inet dhcp
metric 100
# Ethernet internal port on Sager laptop MAC 254
# Internet Gateway 192.168.1.1
auto enp6s0
iface enp6s0 inet dhcp
metric 10
mark@UM1510:~$ sudo /etc/init.d/networking stop
[ ok ] Stopping networking (via systemctl): networking.service.
mark@UM1510:~$ sudo /etc/init.d/networking start
[ ok ] Starting networking (via systemctl): networking.service.
mark@UM1510:~$ route
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
default 192.168.1.1 0.0.0.0 UG 10 0 0 enp6s0
default 192.168.2.1 0.0.0.0 UG 100 0 0 enx00051ba184cb
link-local * 255.255.0.0 U 100 0 0 enx00051ba184cb
192.168.1.0 * 255.255.255.0 U 10 0 0 enp6s0
192.168.2.0 * 255.255.255.0 U 100 0 0 enx00051ba184cb
Results: On site resources are accessible from both networks by file
manager and internet access is available simultaneously.
NOTE: The order of the listed connections in the interfaces file has no
effect on the order of the connections seen in the route report. Instead,
the metric parameter causes the favor of one network over the other and
the resulting position one of the internet connection in the route report.
In the next, example only the metrics are switched in the interfaces file
to favor the enx00051ba184cb
connection over the enp6s0
connection. The network cables are also switched from one interface to the other to keep the network with the lowest metric assigned to the network with the
internet connection. This is noted in the interface file comments below.
/etc/network/interfaces
:
# interfaces(5) file used by ifup(8) and ifdown(8)
auto lo
iface lo inet loopback
# J5 Create USB/Ether Adapter MAC c4b
# Internet Gateway 192.168.1.1
auto enx00051ba184cb
iface enx00051ba184cb inet dhcp
metric 10
# Ethernet internal port on Sager laptop MAC 254
# Subnet Two Gateway 192.168.2.1
auto enp6s0
iface enp6s0 inet dhcp
metric 100
mark@UM1510:~$ sudo /etc/init.d/networking stop
[sudo] password for mark:
[ ok ] Stopping networking (via systemctl): networking.service.
mark@UM1510:~$ sudo /etc/init.d/networking start
[ ok ] Starting networking (via systemctl): networking.service.
mark@UM1510:~$ route
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
default 192.168.1.1 0.0.0.0 UG 10 0 0 enx00051ba184cb
default 192.168.2.1 0.0.0.0 UG 100 0 0 enp6s0
link-local * 255.255.0.0 U 10 0 0 enx00051ba184cb
192.168.1.0 * 255.255.255.0 U 10 0 0 enx00051ba184cb
192.168.2.0 * 255.255.255.0 U 100 0 0 enp6s0
Results: On site resources are accessible by file manager and internet
access is available simultaneously.
All of this was accomplished with no changes made in the Network
Connections GUI offered by Gnome. As a mater of fact the Network
Connections Top Bar menu group in the MATE desktop is inactive with the
interfaces file populated with entries below the lines:
# interfaces(5) file used by ifup(8) and ifdown(8)
auto lo
iface lo inet loopback
I have tried unsuccessfully to achieve the same results I have now achieved with Terrance's support with the Ubuntu Network Connections Manager GUI. Is it possible to migrate all these settings that I have done into the Ubuntu Network Connections Manager GUI ? Then reset the interfaces file back to default? i.e.:
# interfaces(5) file used by ifup(8) and ifdown(8)
auto lo
iface lo inet loopback