There are several similar post on this topic, but none of those give me the answer I need. I hope You can help me. :)

I just flashed latest Raspbian Jessie (uname: Linux raspberrypi 4.9.28-v7+). No additional packets were installed. No network related configuration were performed, except enabling SSH by sudo raspi-config and adding WiFi SSID and password at /etc/wpa_supplicant/wpa_supplicant.conf (according to official Rasberry PI documentation):


When ethernet cable plugged in everything works fine: it has internet connectivity and I can access RPi on local network. Also, when RPi is connected via WiFi, while ethernet is plugged in it is accessible by both interfaces and I can ssh to it by both (eth and wifi) IPs.
The problem is when ethernet is NOT plugged in. Then RPi is INaccessible. No SHH and no netcat -l XXX output (on RPi side).

Routing table with ethernet and with WiFi:

Kernel IP routing table
Destination     Gateway         Genmask         Flags   MSS Window  irtt Iface
default         router         UG        0 0          0 eth0
link-local      *          U         0 0          0 wlan0     *        U         0 0          0 eth0

Routing table without ethernet and with WiFi:

Kernel IP routing table
Destination     Gateway         Genmask         Flags   MSS Window  irtt Iface
link-local      *          U         0 0          0 wlan0

As I mentioned before, it is out-of-the-box software. I want to know why it does not work and how it was released like this? Also, what is the way to fix this without installing whole bunch of stuff and writing tons of scripts/config files.

Thank you in advance

  • I would be a little bit slower with stating why is it released like that when I haven't made sure that it is not my own infrastructure at fault here before blaming Raspbian. Rest asured, networking in Raspbian works really well from my own experience, and I'm doing all kind of weird network stuff. Maybe you want to rephrase your question to not look like a rant? – TheDiveO Jul 26 '17 at 5:25

Beside lacking a non-APIPA IPv4 address, you also lack a default route via the WLAN wlan0 interface. The only route you see is a direct subnet route, probably an APIPA autoconfigured IPv4 subnet (with an additional indication in form of its /16 prefix size).

You need to make sure that the IP network you connect to via WLAN has either a DHCPv4 server running -- or IPv6, or both. The DHCPv4 server then should distribute not only the IPv4 device address and subnet mask, but also the default route and (proxy) DNS server address.

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