multiple interface with dhcp result into wrong metric and gateway (#8668) · Issues · alpine / aports

multiple interface with dhcp result into wrong metric and gateway

I have 2 network interfaces, both are using DHCP, eth0 is for internet, and eth1 is for lan only.

From the wiki: https://wiki.alpinelinux.org/wiki/Multi\_ISP
The DHCP client will automatically add a metric value to the default gateway. It will pick 200 + interface index. Therefore we don’t need to worry about that for DHCP.

But, ifconfig shows metric are both 1, so every time I reboot my system, I have no internet.
The system will pick up the latest up interface as the default gateway.
It is randomly unexpectable.

localhost:~# cat /etc/network/interfaces 
auto lo
iface lo inet loopback

auto eth0
iface eth0 inet dhcp

auto eth1
iface eth1 inet dhcp

localhost:~# netstat -nre
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
0.0.0.0         10.0.2.1        0.0.0.0         UG    202    0        0 eth0
10.0.2.0        0.0.0.0         255.255.255.0   U     0      0        0 eth0
192.168.56.0    0.0.0.0         255.255.255.0   U     0      0        0 eth1

localhost:~# ifconfig 
eth0      Link encap:Ethernet  HWaddr 08:00:27:7B:1A:80  
          inet addr:10.0.2.4  Bcast:0.0.0.0  Mask:255.255.255.0
          inet6 addr: fe80::a00:27ff:fe7b:1a80/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:2 errors:0 dropped:0 overruns:0 frame:0
          TX packets:14 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:1180 (1.1 KiB)  TX bytes:1612 (1.5 KiB)

eth1      Link encap:Ethernet  HWaddr 08:00:27:19:32:A2  
          inet addr:192.168.56.150  Bcast:0.0.0.0  Mask:255.255.255.0
          inet6 addr: fe80::a00:27ff:fe19:32a2/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:203 errors:0 dropped:0 overruns:0 frame:0
          TX packets:133 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:22257 (21.7 KiB)  TX bytes:30775 (30.0 KiB)

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:65536  Metric:1
          RX packets:40 errors:0 dropped:0 overruns:0 frame:0
          TX packets:40 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1 
          RX bytes:2880 (2.8 KiB)  TX bytes:2880 (2.8 KiB)

(from redmine: issue id 8668, created on 2018-03-19)

I have 2 network interfaces, both are using DHCP, eth0 is for internet,
and eth1 is for lan only.

From the wiki: https://wiki.alpinelinux.org/wiki/Multi\_ISP  
The DHCP client will automatically add a metric value to the default
gateway. It will pick 200 + interface index. Therefore we don’t need to
worry about that for DHCP.

But, ifconfig shows metric are both 1, so every time I reboot my system,
I have no internet.  
The system will pick up the latest up interface as the default
gateway.  
It is randomly unexpectable.

localhost:~# cat /etc/network/interfaces 
    auto lo
    iface lo inet loopback

auto eth0
    iface eth0 inet dhcp

auto eth1
    iface eth1 inet dhcp

localhost:~# netstat -nre
    Kernel IP routing table
    Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
    0.0.0.0         10.0.2.1        0.0.0.0         UG    202    0        0 eth0
    10.0.2.0        0.0.0.0         255.255.255.0   U     0      0        0 eth0
    192.168.56.0    0.0.0.0         255.255.255.0   U     0      0        0 eth1

localhost:~# ifconfig 
    eth0      Link encap:Ethernet  HWaddr 08:00:27:7B:1A:80  
              inet addr:10.0.2.4  Bcast:0.0.0.0  Mask:255.255.255.0
              inet6 addr: fe80::a00:27ff:fe7b:1a80/64 Scope:Link
              UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
              RX packets:2 errors:0 dropped:0 overruns:0 frame:0
              TX packets:14 errors:0 dropped:0 overruns:0 carrier:0
              collisions:0 txqueuelen:1000 
              RX bytes:1180 (1.1 KiB)  TX bytes:1612 (1.5 KiB)

eth1      Link encap:Ethernet  HWaddr 08:00:27:19:32:A2  
              inet addr:192.168.56.150  Bcast:0.0.0.0  Mask:255.255.255.0
              inet6 addr: fe80::a00:27ff:fe19:32a2/64 Scope:Link
              UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
              RX packets:203 errors:0 dropped:0 overruns:0 frame:0
              TX packets:133 errors:0 dropped:0 overruns:0 carrier:0
              collisions:0 txqueuelen:1000 
              RX bytes:22257 (21.7 KiB)  TX bytes:30775 (30.0 KiB)

lo        Link encap:Local Loopback  
              inet addr:127.0.0.1  Mask:255.0.0.0
              inet6 addr: ::1/128 Scope:Host
              UP LOOPBACK RUNNING  MTU:65536  Metric:1
              RX packets:40 errors:0 dropped:0 overruns:0 frame:0
              TX packets:40 errors:0 dropped:0 overruns:0 carrier:0
              collisions:0 txqueuelen:1 
              RX bytes:2880 (2.8 KiB)  TX bytes:2880 (2.8 KiB)

*(from redmine: issue id 8668, created on 2018-03-19)*

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