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Re: Temporary failure in name resolution



I have reorganized the content below to improve comprehension.


On 3/31/21 9:46 AM, Dan Norton wrote:
Thanks to all who responded.
> Thanks for your detailed help. Let me know if I can dig out more.

YW.  We are making progress.  See below.


Have not changed any of the gateway settings that I'm aware of.


Okay.


This problem makes me post from a Windows laptop and transfer terminal output via thumb drive to the laptop. Not pretty.


Sneakernet works. :-)


> This laptop is the only other computer but it runs Windows. Is that testing name resolution with another computer?


Shutdown the Debian computer. Shutdown the Windows laptop. Look at the LED's on the AT&T gateway so that you know their state when it is operating. Power off the gateway. Unpatch the Ethernet cable connected to the laptop (e.g. disconnect both ends). Wait at least 2 minutes. Boot the laptop and disable or delete all network connections. Reboot Windows and verify that all network connections are down or gone. Power up the gateway. Wait for the LED's to return to the operating state. Patch the laptop to the gateway with an Ethernet cable. Configure or create an Ethernet network connection to the gateway in Windows. Fix any problems and verify everything works (contact AT&T technical support if necessary). Stop the Ethernet connection in Windows. Configure or create a Wi-Fi network connection to the gateway in Windows. Fix any problems and verify everything works (contact AT&T technical support if necessary). Turn off the Wi-Fi connection in Windows. Choose either the Ethernet network connection or the Wi-Fi network connection, and enable one.


Ensure that the Debian computer is connected to the gateway with an Ethernet cable via the primary Ethernet port. Unpatch all cables connected to all other Ethernet ports. Boot the Debian computer.


> Yes, I have done a cold reboot [of the Debian computer] since upgrading.


Okay.


> # cat /etc/debian_version ; uname -a
> 10.9
> Linux deb4 4.19.0-16-amd64 #1 SMP Debian 4.19.181-1 (2021-03-19) x86_64 GNU/Linux


Okay.  Those are current.


> # ifconfig eno1
> eno1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
> inet 192.168.1.66 netmask 255.255.255.0 broadcast 192.168.1.255 > inet6 ****:****:***:****:****:****:****:**** prefixlen 64 scopeid 0x0<global> > inet6 ****::****:****:****:**** prefixlen 64 scopeid 0x20<link>
>          ether **:**:**:**:**:**  txqueuelen 1000  (Ethernet)
>          RX packets 10009  bytes 1101640 (1.0 MiB)
>          RX errors 0  dropped 0  overruns 0  frame 0
>          TX packets 1734  bytes 180973 (176.7 KiB)
>          TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0


Okay.


> # cd /etc
> # cat resolv.conf
> domain attlocal.net
> search attlocal.net
> nameserver 192.168.1.254
> [something removes additional nameserver lines that I add]


Okay.  For now, do not try to edit that file.


# apt update
0% [Connecting to deb.debian.org] [Connecting to qgis.org] [Connecting to brave-browser-apt-release.s3.brave.com]^C
[cancelled early]

# apt update
Err:1 http://deb.debian.org/debian buster InRelease
   Temporary failure resolving 'deb.debian.org'
Err:2 https://qgis.org/debian buster InRelease
   Temporary failure resolving 'qgis.org'
Err:3 https://brave-browser-apt-release.s3.brave.com stable InRelease
   Temporary failure resolving 'brave-browser-apt-release.s3.brave.com'
0% [Working]^C
[cancelled later]

# apt upgrade
Reading package lists... Done
Building dependency tree
Reading state information... Done
Calculating upgrade... Done
The following packages were automatically installed and are no longer required:
   libqgis-3d3.18.0 libqgis-analysis3.18.0 libqgis-app3.18.0 libqgis-core3.18.0 libqgis-gui3.18.0
   libqgis-native3.18.0 libqgis-server3.18.0 libqgisgrass7-3.18.0 libqgispython3.18.0
Use 'apt autoremove' to remove them.
The following NEW packages will be installed:
   libqgis-3d3.18.1 libqgis-analysis3.18.1 libqgis-app3.18.1 libqgis-core3.18.1 libqgis-gui3.18.1
   libqgis-native3.18.1 libqgis-server3.18.1 libqgisgrass7-3.18.1 libqgispython3.18.1
The following packages will be upgraded:
   libqgis-customwidgets python3-qgis python3-qgis-common qgis qgis-common qgis-plugin-grass
   qgis-plugin-grass-common qgis-provider-grass qgis-providers qgis-providers-common
10 upgraded, 9 newly installed, 0 to remove and 0 not upgraded.
Need to get 105 MB of archives.
After this operation, 91.5 MB of additional disk space will be used.
Do you want to continue? [Y/n] y
Err:1 https://qgis.org/debian buster/main amd64 qgis-plugin-grass amd64 1:3.18.1+15buster
   Temporary failure resolving 'qgis.org'
[this continues to Err:19 then more]


So, the updates/ upgrades are incomplete because you need packages and the DNS problems are preventing apt-get(8) from fetching the packages needed to complete the updates/ upgrades. A Catch-22 situation...


Have you modified /etc/apt/sources.list or added any configuration files in directory /etc/apt/sources.list.d ? Please run these commands and post your console session:

$ ls -R /etc/apt/sources.list*

$ cat /etc/apt/sources.list

$ cat /etc/apt/sources.list.d/*


Use the laptop to find the IP addresses of all of the servers listed above. On the Debian machine, create /etc/hosts entries for those hosts. For example:

151.101.126.132    deb.debian.org
151.101.66.132     security.debian.org


Then try 'apt-get update' and 'apt-get upgrade' again. If you see more DNS complaints, press Ctrl+C, look up the IP addresses, add hosts(5) entries, and repeat until apt-get(8) works.



$ nmcli g status
$ nmcli c show
$ nmcli d show
[I don't seem to have nmcli]

Okay.


# host -v -t A www.debian.org 8.8.8.8
Trying "www.debian.org"
Using domain server:
Name: 8.8.8.8
Address: 8.8.8.8#53
Aliases:

;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 58963
;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;www.debian.org.			IN	A

;; ANSWER SECTION:
www.debian.org.		299	IN	A	128.31.0.62
www.debian.org.		299	IN	A	149.20.4.15

Received 64 bytes from 8.8.8.8#53 in 102 ms

# host -v -t A www.debian.org
Trying "www.debian.org"
;; connection timed out; no servers could be reached


Please verify that the DNS proxy server on the AT&T gateway is working:

$ host -v -t A www.debian.org 192.168.1.254


AIUI your Debian computer has a second Ethernet port and you want to use the computer as a router-behind-a-router. What ISO image did you install from, how did you install, and what configuration settings have you made to achieve this functionality?


David


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