Client has DNS but no TCP/IP access when connected to Debian host via WiFi

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debian_wifi_user
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Client has DNS but no TCP/IP access when connected to Debian host via WiFi

#1 Post by debian_wifi_user »

I have used NetworkManager to create a "Wi-Fi (shared)" connection as my Debian machine is connected to the internet with a wired connection and I want to share that internet connection with other WiFi devices.

I can connect to the Debian machine over WiFi from an Ubuntu "client" and can ping the Debian access point. I can also ping google.com from the Ubuntu client.

Unfortunately the Ubuntu machine cannot actually connect to any websites. All it can do is ping domains. EDIT: The ping does not actually work - only the domain resolving works. Sorry for my confusion.

What is wrong with my setup? I have the defaults set and was hoping that the NetworkManager wizard would "just work". ;-)
Last edited by debian_wifi_user on 2022-01-17 00:16, edited 1 time in total.

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argentwolf
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Re: Client has DNS but no TCP/IP access when connected to Debian host via WiFi

#2 Post by argentwolf »

You do have a Wireless Access Point (WAP) or you're trying to make your Debian machine with a wireless NIC a WAP?

https://wiki.debian.org/NetworkManager
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Re: Client has DNS but no TCP/IP access when connected to Debian host via WiFi

#3 Post by reinob »

If you can "ping domains" from your Ubuntu client it means that both DNS resolution and routing should be working fine.

Can you actual resolve domains, or have you pinged 1.1.1.1 or 8.8.8.8 or such?
If domain resolution does NOT work (check with e.g. "host www.google.com"), have a look at your /etc/resolv.conf (again, in your client, not at the debian host).

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Re: Client has DNS but no TCP/IP access when connected to Debian host via WiFi

#4 Post by ralph.ronnquist »

You might need to tell the debian machine kernel that forwarding is ok, by

Code: Select all

# sysctl net.ipv4.ip_forward=1
And for convenience you might also want to add the setting into a file in /etc/systctl.d/

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Re: Client has DNS but no TCP/IP access when connected to Debian host via WiFi

#5 Post by debian_wifi_user »

argentwolf wrote: 2022-01-14 00:03 You do have a Wireless Access Point (WAP) or you're trying to make your Debian machine with a wireless NIC a WAP?

https://wiki.debian.org/NetworkManager
I want to setup my Debian machine as a wireless access point.

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Re: Client has DNS but no TCP/IP access when connected to Debian host via WiFi

#6 Post by debian_wifi_user »

reinob wrote: 2022-01-14 07:32 If you can "ping domains" from your Ubuntu client it means that both DNS resolution and routing should be working fine.

Can you actual resolve domains, or have you pinged 1.1.1.1 or 8.8.8.8 or such?
If domain resolution does NOT work (check with e.g. "host www.google.com"), have a look at your /etc/resolv.conf (again, in your client, not at the debian host).
I cannot ping 1.1.1.1 from the Ubuntu client.

If I ping google.com, it resolves the IP address but the ping fails. Sorry for my original post where I said I could ping domains - I cannot. All I see is it resolve the domain and fail to ping.

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Re: Client has DNS but no TCP/IP access when connected to Debian host via WiFi

#7 Post by debian_wifi_user »

ralph.ronnquist wrote: 2022-01-14 09:37 You might need to tell the debian machine kernel that forwarding is ok, by

Code: Select all

# sysctl net.ipv4.ip_forward=1
And for convenience you might also want to add the setting into a file in /etc/systctl.d/
I tried this but it didn't change anything alas.

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Re: Client has DNS but no TCP/IP access when connected to Debian host via WiFi

#8 Post by ralph.ronnquist »

And then you probably also need the debian machine to masquerade the network traffic, which you'd do as follows with iptables installed and assuming your Ethernet interface name is ens5:

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# iptables -t nat -A POSTROUTING -o ens5 -j MASQUERADE

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Re: Client has DNS but no TCP/IP access when connected to Debian host via WiFi

#9 Post by debian_wifi_user »

ralph.ronnquist wrote: 2022-01-17 05:31 And then you probably also need the debian machine to masquerade the network traffic, which you'd do as follows with iptables installed and assuming your Ethernet interface name is ens5:

Code: Select all

# iptables -t nat -A POSTROUTING -o ens5 -j MASQUERADE
Thanks a lot. This almost got me there. I ran this command and it said:

Code: Select all

iptables v1.8.7 (nf_tables):  CHAIN_ADD failed (Operation not supported): chain POSTROUTING
After finding this link https://raspberrypi.stackexchange.com/q ... supported , I ran this command first:

Code: Select all

 # update-alternatives --set iptables /usr/sbin/iptables-legacy
update-alternatives: using /usr/sbin/iptables-legacy to provide /usr/sbin/iptables (iptables) in manual mode
And now it all works. Thanks again.

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Re: Client has DNS but no TCP/IP access when connected to Debian host via WiFi

#10 Post by argentwolf »

Huh! 'Raspberry Pi' is important information given at the beginning of your request for help...
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Re: Client has DNS but no TCP/IP access when connected to Debian host via WiFi

#11 Post by debian_wifi_user »

argentwolf wrote: 2022-01-18 14:05 Huh! 'Raspberry Pi' is important information given at the beginning of your request for help...
Why? I'm not using a Raspberry Pi.

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Re: Client has DNS but no TCP/IP access when connected to Debian host via WiFi

#12 Post by argentwolf »

My bad! :oops:
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