Can I use eth0 and wlan0 at the same time in diffrent purpose?

Question

I use Raspbian Jessi(kernel v4.4) on Raspberry pi 3.

These are my configurations.

pi@raspberrypi:~ $ cat /etc/network/interfaces
source-directory /etc/network/interfaces.d
auto lo
iface lo inet loopback

auto eth0
iface eth0 inet manual

auto wlan0
allow-hotplug wlan0
iface wlan0 inet dhcp
wpa-conf /etc/wpa_supplicant/wpa_supplicant.conf

allow-hotplug wlan1
iface wlan1 inet manual
wpa-conf /etc/wpa_supplicant/wpa_supplicant.conf

iface default inet dhcp

pi@raspberrypi:~ $ cat /etc/dhcpcd.conf
--   default   --
    ........
--   default   --

interface eth0
static ip_address=10.0.0.4

pi@raspberrypi:~ $ ifconfig
eth0      Link encap:Ethernet  HWaddr b8:27:eb:35:80:7b
      inet addr:10.0.0.4  Bcast:10.255.255.255  Mask:255.0.0.0
      inet6 addr: fe80::e38f:f977:c7d9:c394/64 Scope:Link
      UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
      RX packets:13103 errors:0 dropped:0 overruns:0 frame:0
      TX packets:18870 errors:0 dropped:0 overruns:0 carrier:0
      collisions:0 txqueuelen:1000
      RX bytes:1116394 (1.0 MiB)  TX bytes:21546414 (20.5 MiB)

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:8284 errors:0 dropped:0 overruns:0 frame:0
      TX packets:8284 errors:0 dropped:0 overruns:0 carrier:0
      collisions:0 txqueuelen:1
      RX bytes:20791523 (19.8 MiB)  TX bytes:20791523 (19.8 MiB)
wlan0     Link encap:Ethernet  HWaddr b8:27:eb:60:d5:2e
      inet addr:192.168.0.139  Bcast:192.168.0.255  Mask:255.255.255.0
      inet6 addr: fe80::ba27:ebff:fe60:d52e/64 Scope:Link
      UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
      RX packets:13334 errors:0 dropped:87 overruns:0 frame:0
      TX packets:4495 errors:0 dropped:0 overruns:0 carrier:0
      collisions:0 txqueuelen:1000
      RX bytes:10853548 (10.3 MiB)  TX bytes:473468 (462.3 KiB)

My laptop(window 10, MSI 6QE leopard pro) connects to the Raspberry Pi through LAN cable. I can remote the Pi with putty in SSH. At the same time, my laptop connects to the internet with wifi.

Pi can connect to the internet with wifi(ping and apt-get are possible). the problem is when I put the LAN cable to remote the machine, only ping to 8.8.8.8 is possible and nothing works. (ping 8.8.8.8 OK. apt-get can't find the host)

Can I use the internet while LAN cable is connected?

Your /etc/network/interfaces is the illegitimate offspring of 2 different networking methods (and is not correct for either) so it is difficult to predict what it will do. How do I set up networking/WiFi/Static IP describes the standard Raspbian setup which enables both. The older standard (which is one of the parents of your current config) generally allows only a single interface. Other methods e.g. network-manager provide finer control as does manual configuration. You need to decide exactly what you are trying to achieve. — Milliways, Jul 10 '16 at 11:27

score 2 · Accepted Answer · edited Apr 13 '17 at 12:56

This shouldn't be a problem.

Unfortunately I don't use /etc/net/interfaces or dhcpcd and friends so cannot say what might be right or wrong there; in my opinion it is easier to just disable these things and set stuff up manually, but that is an eccentricity of mine and not something I should recommend generally.

However, I can make a guess and a suggestion if no one comes along with anything more proper:

ifplugd is a background daemon that detects and responds to plugging in an ethernet cable and it will mess with you. I am not positive it is still being used on Raspbian; it isn't on the -lite image, but likely it is on the standard one -- check with ps -C ifplugd. If it shows up, systemctl stop ifplugd and check again. If it is still there, try disabling it as described in the answer to the question linked above and reboot, then check again.
Once ifplugd is out of the picture, comment everything about eth0 out of /etc/network/interfaces; also remove references to it in dhcpcd.conf. Then reboot.

On first glance in your scenario it sounds as if you require the ethernet connection just to access the pi, but if you are plugging in the cable during runtime and noting a loss of internet that is not the case.

If you do already have access, then you should be able to run these commands one way or another when you attach to the PC:
```
sudo ip link set eth0 up
sudo ip addr add 10.0.0.4/24 eth0
```
If not you can add them to /etc/rc.local without sudo but this requires the cable be attached when you boot.

I think this should be sufficient for you to connect with PuTTY. If there are problems you could also try:

sudo ip route add 10.0.0.0/24 dev eth0

You might want to use that in the first place, actually -- I don't think it can create a problem, it may just be superfluous in this context.

Thanks so much, but ifplugd is not exist on my latest version of raspbian. I solved this problem few minute ago. I set DNS server as 8.8.8.8 and it worked. — Teul Jung, Jul 10 '16 at 12:37

score 0 · Answer 2 · answered Jul 10 '16 at 12:58

0

I set DNS server as 8.8.8.8 and it worked. sudo nano /etc/resolv.config

change nameserver address to 8.8.8.8

answered Jul 10 '16 at 12:58

Teul Jung

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Can I use eth0 and wlan0 at the same time in diffrent purpose?

2 Answers2