USB tethering the Raspberry Pi 5 to Android Phone (no DNS)

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Discussion Overview

The discussion revolves around the challenges of USB tethering a Raspberry Pi 5 to an Android phone, specifically focusing on issues related to DNS resolution when accessing the internet through the tethered connection. Participants explore various configurations and troubleshooting steps to establish a functional network connection.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Exploratory

Main Points Raised

  • One participant notes that unlike previous Raspberry Pi models, the Pi 5 does not automatically recognize the tethered connection, showing "wwan0" instead of "usb0".
  • Another participant suggests editing the /etc/resolv.conf file to manually add a nameserver, as they have experienced similar issues in the past.
  • A participant mentions that their /etc/resolv.conf already contains 8.8.8.8, indicating that the nameserver is set but DNS resolution still fails.
  • Discussion arises about the role of NetworkManager, with one participant questioning whether it is managing the connection, as they have had issues with it in the past.
  • Another participant points out that resolv.conf is regenerated on reboots and when network changes occur, which could affect DNS settings.
  • One participant proposes using the phone's gateway as a nameserver, suggesting that it might resolve the issue, while acknowledging that changes to resolv.conf may not persist.
  • A later reply indicates that modifying dhclient.conf to prepend a specific nameserver resolved their issue, but they also note that NetworkManager does not recognize the wwan0 connection.
  • Participants discuss the possibility that the Pi 5 is treating the phone as a hardware modem, complicating the use of NetworkManager.

Areas of Agreement / Disagreement

Participants express various approaches to the problem, with no consensus on a single solution. Some suggest manual configuration while others point to potential limitations with NetworkManager and the recognition of the connection type.

Contextual Notes

There are indications that the behavior of resolv.conf and the management of network connections by NetworkManager may vary based on specific configurations and device recognition, which remains unresolved in the discussion.

Swamp Thing
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My previous Raspberry Pi boards were able to tether to a mobile phone and access the shared internet connection without having to do anything special except enabling USB tethering on the phone after connecting the cable.

Now on the Pi 5, this doesn't happen seamlessly. So I tried the instructions given here.

There was one minor difference from the article: after plugging in the cable, iwconfig is supposed to show a new item called usb0 (or usb1 etc), according to the article. In my case, the new item was called "wwan0".

Anyway, I followed the next step which was dhclient wwan0 where I replaced usb(x) with wwan0.

After this, a new network interface appeared in the ifconfig output.
Code: 
wwan0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.25.16  netmask 255.255.255.0  broadcast 192.168.25.255
        inet6 fe80::30f8:45ff:febd:6e9b  prefixlen 64  scopeid 0x20<link>
        ether 32:f8:45:bd:6e:9b  txqueuelen 1000  (Ethernet)
        RX packets 0  bytes 0 (0.0 B)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 0  bytes 0 (0.0 B)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

At this point I was able to ping 8.8.8.8 through the tethered phone. I was also able to ping servers whose IP I found using the WiFi connection. However, ping (and the web browser) could not resolve DNS through the tethered connection. ping: www.aldaily.com: Temporary failure in name resolution

How can I set this connection to use say 8.8.8.8 as its DNS server? (or to use the phone's IP, which I found using nmap, which presumabley offers DNS)? Or alternatively, is there an entirely different and better way to set the whole thing up?
 
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I've had this problem a bunch of times before on compute 4. You can ping 8.8.8.8 or 1.1.1.1 or whatever but you aren't able to completely resolve hostnames. So if you tried ping google.com or ping github.com you'd be unable to reach either.

What normally fixes this issue for me is viming into /etc/resolv.conf and explictly adding the nameserver on the pi. Have you tried that?
 
QuarkyMeson said:
I've had this problem a bunch of times before on compute 4. You can ping 8.8.8.8 or 1.1.1.1 or whatever but you aren't able to completely resolve hostnames. So if you tried ping google.com or ping github.com you'd be unable to reach either.

What normally fixes this issue for me is viming into /etc/resolv.conf and explictly adding the nameserver on the pi. Have you tried that?

I just looked at resolv.conf -- 8.8.8.8 was in there already...

Code: 
# Generated by NetworkManager
nameserver 8.8.8.8
 
Hmmmm. Can you check Networkmanager.conf? Does that look right?

This is the problem I have with linux, there are too many ways to skin this cat. If you aren't actually using NetworkManager then none of this matters. I've only ever used NetworkManager though because it's the simplest to deal with.
 
My NetworkManager.conf ...
Code: 
[main]
plugins=ifupdown,keyfile

[ifupdown]
managed=false

[device]
wifi.scan-rand-mac-address=no
 
Ok, so NetworkManager isn't managing this connection, but its still generating the resolv.conf... Can you try this?

In resolv.conf can you add the nameserver 192.168.25.1?

Can you also run ls -l /etc/resolv.conf?

Could you also tell me whats in /etc/network/interfaces?
 
Code: 
$ ls -l /etc/resolv.conf
-rw-r--r-- 1 root root 26 May 28 18:54 /etc/resolv.conf

/etc/network doesn't have anything called interfaces...
Code: 
$ ls -l /etc/network
total 16
drwxr-xr-x 2 root root 4096 Nov 19  2024 if-down.d
drwxr-xr-x 2 root root 4096 Nov 19  2024 if-post-down.d
drwxr-xr-x 2 root root 4096 Nov 19  2024 if-pre-up.d
drwxr-xr-x 2 root root 4096 Nov 19  2024 if-up.d


QuarkyMeson said:
In resolv.conf can you add the nameserver 192.168.25.1?
I will try this later and report...
 
resolv.conf doesn't retain its contents across reboots; it even changes when you turn on/off Wireless LAN.

With the wireless lan turned off, there are no entries in it. With Wifi turned ON, it looks like this...

# Generated by NetworkManager
nameserver 182.237.9.10
nameserver 8.8.8.8
nameserver fe80::1%wlan0

In fact, the mousepad text editor reports that the file was changed and offers to reload the contents when you toggle the wifi :smile:
 
Yeah, resolv.conf is regenerated on reboots/when networkmanager sees changes.
Did it start working after it was recreated?
 
  • #10
QuarkyMeson said:
Yeah, resolv.conf is regenerated on reboots/when networkmanager sees changes.
Did it start working after it was recreated?
Sadly, no.
 
  • #11
Try adding in the nameserver 192.168.25.1(assuming its same ip) to resolv.conf. It won't persist, but it might need to use phone gateway as nameserver. If this works though, I think the real fix is not use dhclient and use NetworkManager.
 
Last edited:
  • #12
Found this by searching for "dhclient dns server" and looking at the lower-ranked results that I had missed before... https://superuser.com/questions/944...tax-for-the-dhclient-conf-supersede-statement

Uncomment this line in dhclient.conf:
# prepend domain-name-servers 127.0.0.1

and add 8.8.8.8 (comma separated).

It's working now.

-------------------

QuarkyMeson said:
the real fix is not use dhclient and use NetworkManager.
nmcli con doesn't show wwan0 in the list of network connections. So this doesn't work:
Code: 
$ nmcli con mod "wwan0" ipv4.dns "8.8.8.8"
Error: unknown connection 'wwan0'

Edit:

I think the problem with NetworkManager in my case is that the Pi-5 sees the phone as a hardware modem rather than as a raw IP-over-USB connection. That is why it is named "wwan0" rather than "usb0". And NetworkManager can manage usb0 type connections but not wwan0 type modem interfaces.

From what I could learn online, my Pi-5 is probably running PPP over a serial USB link to the phone.:oops:
 
Last edited:
  • #13
Ah you'd want to do nmcli device status, make sure its there. If its unmanaged (yes probably) you'd have to tell networkmanager to manage it. Then you can create a profile for it.

Not really important since you already have a solution thats working for you.