[Solved] apt problem with dns

[Probzx]

Hello,

I have a problem on one of my server when I try to update or install new package using apt.
Off course, I already check my resolv.conf configuration and I can ping deb.debian.org and other domains without any problem.
Curl is also working.
Do you have any idea of a solution to fix that ?

When I use "apt update", I have this error :

Code: Select all

Ign :1 https://deb.debian.org/debian bookworm InRelease
Ign :2 https://security.debian.org/debian-security bookworm-security InRelease
Ign :3 https://deb.debian.org/debian bookworm-updates InRelease
Ign :2 https://security.debian.org/debian-security bookworm-security InRelease
Ign :1 https://deb.debian.org/debian bookworm InRelease
Ign :3 https://deb.debian.org/debian bookworm-updates InRelease
Ign :2 https://security.debian.org/debian-security bookworm-security InRelease
Ign :1 https://deb.debian.org/debian bookworm InRelease
Ign :3 https://deb.debian.org/debian bookworm-updates InRelease
Err :2 https://security.debian.org/debian-security bookworm-security InRelease
   Temporary "security.debian.org" resolution error "
Err :1 https://deb.debian.org/debian bookworm InRelease
  Temporary « deb.debian.org resolution error »
Err :3 https://deb.debian.org/debian bookworm-updates InRelease
  Temporary "deb.debian.org" resolution error
Reading package lists... Done
Build dependency tree... Done
Read status information... Done
All packages are up to date.
W: Unable to retrieve https://deb.debian.org/debian/dists/bookworm/InRelease Temporary error resolving "deb.debian.org".
W: Unable to recover https://deb.debian.org/debian/dists/bookworm-updates/InRelease Temporary "deb.debian.org" resolution error.
W: Unable to recover https://security.debian.org/debian-security/dists/bookworm-security/InRelease Temporary "security.debian.org" resolution error
W: Download of some index files failed, they were ignored, or old ones were used instead.

My sources.list configuration :

Code: Select all

deb https://deb.debian.org/debian bookworm main contrib non-free non-free-firmware
deb https://deb.debian.org/debian bookworm-updates main contrib non-free non-free-firmware
deb https://security.debian.org/debian-security bookworm-security main contrib non-free non-free-firmware

Thanks you very much !

[lindi]

Your DNS does not seem to be working?

[Probzx]

I can resolve domain, ping to any domain like google or deb.debian.org work.
Nslookup to all valid domain also work well, it's very strange I can't explain why the apt return me this result about domain resolution.

[fabien]

Debug options could give more clues. The LANG="C" prefix allows output in English.

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#> LANG="C" apt -o "Debug::Acquire::https=1" -o "Debug::Acquire::http=1" -o "Debug::Acquire::ftp=1" update

[Probzx]

Hello,

Thanks for your help.
Here is the output of this command :

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Ign:1 https://deb.debian.org/debian bookworm InRelease
Ign:2 https://deb.debian.org/debian bookworm-updates InRelease
Ign:3 https://security.debian.org/debian-security bookworm-security InRelease
Ign:3 https://security.debian.org/debian-security bookworm-security InRelease
Ign:1 https://deb.debian.org/debian bookworm InRelease
Ign:2 https://deb.debian.org/debian bookworm-updates InRelease
Ign:3 https://security.debian.org/debian-security bookworm-security InRelease
Ign:1 https://deb.debian.org/debian bookworm InRelease
Ign:2 https://deb.debian.org/debian bookworm-updates InRelease
Err:3 https://security.debian.org/debian-security bookworm-security InRelease
  Temporary failure resolving 'security.debian.org'
Err:1 https://deb.debian.org/debian bookworm InRelease
  Temporary failure resolving 'deb.debian.org'
Err:2 https://deb.debian.org/debian bookworm-updates InRelease
  Temporary failure resolving 'deb.debian.org'
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
All packages are up to date.
W: Failed to fetch https://deb.debian.org/debian/dists/bookworm/InRelease  Temporary failure resolving 'deb.debian.org'
W: Failed to fetch https://deb.debian.org/debian/dists/bookworm-updates/InRelease  Temporary failure resolving 'deb.debian.org'
W: Failed to fetch https://security.debian.org/debian-security/dists/bookworm-security/InRelease  Temporary failure resolving 'security.debian.org'
W: Some index files failed to download. They have been ignored, or old ones used instead.

[fabien]

Here is the output of this command :

Hello, thanks. Please use code tags when pasting terminal output: select the relevant part of your post and then click the code button. Please edit your previous posts accordingly.

The debug options do not provide more information.

I tested by disabling name resolution on my system and this is what I get:

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#> LANG="C" apt -o "Debug::Acquire::https=1" -o "Debug::Acquire::http=1" -o "Debug::Acquire::ftp=1" update 
Ign:1 https://deb.debian.org/debian bookworm InRelease
Ign:2 https://deb.debian.org/debian-security bookworm-security InRelease
Ign:3 https://deb.debian.org/debian bookworm-updates InRelease
Ign:1 https://deb.debian.org/debian bookworm InRelease
Ign:2 https://deb.debian.org/debian-security bookworm-security InRelease
Ign:3 https://deb.debian.org/debian bookworm-updates InRelease
Ign:1 https://deb.debian.org/debian bookworm InRelease
Ign:2 https://deb.debian.org/debian-security bookworm-security InRelease
Ign:3 https://deb.debian.org/debian bookworm-updates InRelease
Err:1 https://deb.debian.org/debian bookworm InRelease
  Could not resolve 'deb.debian.org'
Err:2 https://deb.debian.org/debian-security bookworm-security InRelease
  Could not resolve 'deb.debian.org'
Err:3 https://deb.debian.org/debian bookworm-updates InRelease
  Could not resolve 'deb.debian.org'
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
All packages are up to date.
W: Failed to fetch https://deb.debian.org/debian/dists/bookworm/InRelease  Could not resolve 'deb.debian.org'
W: Failed to fetch https://deb.debian.org/debian-security/dists/bookworm-security/InRelease  Could not resolve 'deb.debian.org'
W: Failed to fetch https://deb.debian.org/debian/dists/bookworm-updates/InRelease  Could not resolve 'deb.debian.org'
W: Some index files failed to download. They have been ignored, or old ones used instead.

I'm not sure what "Temporary failure resolving" means versus "Could not resolve". I'm going to do some research.

[fabien]

The "Temporary failure resolving" message is triggered by the EAI_AGAIN C error.

EAI_AGAIN
The name server returned a temporary failure indication. Try again later.

This indicates a problem with your proxy (are you using a proxy?) or with your name server.
According to this page:

EAI_AGAIN actually means a temporary failure in name resolution or simply the name server returned a temporary failure indication.
[...]
EAI_AGAIN is actually a DNS lookup timed out error means it is either a network connectivity error or some proxy related error.

If your problem is not caused by a proxy, you can try using another DNS (how to do this may depend on your configuration). Another possibility would be to use another Debian mirror.

[Probzx]

The "Temporary failure resolving" message is triggered by the EAI_AGAIN C error.

EAI_AGAIN
The name server returned a temporary failure indication. Try again later.

This indicates a problem with your proxy (are you using a proxy?) or with your name server.
According to this page:

EAI_AGAIN actually means a temporary failure in name resolution or simply the name server returned a temporary failure indication.
[...]
EAI_AGAIN is actually a DNS lookup timed out error means it is either a network connectivity error or some proxy related error.

If your problem is not caused by a proxy, you can try using another DNS (how to do this may depend on your configuration). Another possibility would be to use another Debian mirror.

Hello,

Thanks for your answer.
It's strange, I don't use any proxy on my server.
I have tried to change my DNS to 1.1.1.1, it return me the same output, but I still can ping or resolve any domain like before.
I also tried to change the repository to ftp.debian.de.org for a test, no change.

Do you think it's possible to "repair" my apt ? I mean, it seeams to be an apt or source probleme because it looks like the network works great.

Thanks a lot.

[vng2022]

What is an output of these two commands

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dig deb.debian.org
dig @1.1.1.1 deb.debian.org

[fabien]

I support @vng2022 request. Also, have you rebooted since the problem occurred? Maybe also restart your router/gateway (wild guess).
If you can afford a reboot, can you test with a live image to see if the behaviour is the same? Otherwise, test with another system on the same network?

[wizard10000]

I had this happen to me on one of three Sid machines last week when I was running routine updates. I'm running Google's DNS at the router; I rebooted the broken machine and the router and everything came back up.

[Probzx]

What is an output of these two commands

Code: Select all

dig deb.debian.org
dig @1.1.1.1 deb.debian.org

Here is the ouput of these two commands :

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dig deb.debian.org

; <<>> DiG 9.18.19-1~deb12u1-Debian <<>> deb.debian.org
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 59300
;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 0

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

;; ANSWER SECTION:
deb.debian.org.         990     IN      CNAME   debian.map.fastlydns.net.
debian.map.fastlydns.net. 13    IN      A       199.232.170.132

;; Query time: 0 msec
;; SERVER: 192.168.0.254#53(192.168.0.254) (UDP)
;; WHEN: Fri Jan 26 17:19:08 CET 2024
;; MSG SIZE  rcvd: 86

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; <<>> DiG 9.18.19-1~deb12u1-Debian <<>> @1.1.1.1 deb.debian.org
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 49460
;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1232
;; QUESTION SECTION:
;deb.debian.org.                        IN      A

;; ANSWER SECTION:
deb.debian.org.         3153    IN      CNAME   debian.map.fastlydns.net.
debian.map.fastlydns.net. 14    IN      A       199.232.150.132

;; Query time: 4 msec
;; SERVER: 1.1.1.1#53(1.1.1.1) (UDP)
;; WHEN: Fri Jan 26 17:19:29 CET 2024
;; MSG SIZE  rcvd: 97

I already reboot my Debian server.
I will reboot both my router and my server check if it resolve this problem.

Thanks for your help

[lindi]

If you want to test dns lookups you should use

Code: Select all

getent hosts deb.debian.org

Programs like "dig" do DNS lookups completely differently from normal programs and might mask problems.

[Probzx]

If you want to test dns lookups you should use

Code: Select all

getent hosts deb.debian.org

Programs like "dig" do DNS lookups completely differently from normal programs and might mask problems.

Thanks for your help.
Here is the output of this command :

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2a04:4e42:6a::644 debian.map.fastlydns.net deb.debian.org

I also reboot my router, it return me the same error output.

[fabien]

Here is the output of this command :

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2a04:4e42:6a::644 debian.map.fastlydns.net deb.debian.org

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$> getent ahosts deb.debian.org

displays IPv4 in addition.

I also reboot my router, it return me the same error output.

It is important that you test with a live image so that we know which side the problem is.

[fabien]

Hello @Probzx, have you done the requested test? Have you made any progress?

[Probzx]

Hello @Probzx, have you done the requested test? Have you made any progress?

Hello Fabien,

I made a test with a live CD on my VM and I did not find any DNS problem.
It seems like the problem come from the system himself

Thanks for your help !

[fabien]

Hello Probzx,
Thanks for updating your topic.

I made a test with a live CD on my VM and I did not find any DNS problem.

Is this VM hosted on the problematic system or on another system on the same network?

Could you please test with only this in the sources.list of the problematic system:

Code: Select all

deb https://199.232.170.132/debian/ bookworm main

This triggers an error, but this error shows an handshake attempt on my system:

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#> apt update
Ign:1 https://199.232.170.132/debian bookworm InRelease
Ign:1 https://199.232.170.132/debian bookworm InRelease
Ign:1 https://199.232.170.132/debian bookworm InRelease
Err:1 https://199.232.170.132/debian bookworm InRelease
  Certificate verification failed: The certificate is NOT trusted. The name in the certificate does not match the expected.  Could not handshake: Error in the certificate verification. [IP: 199.232.170.132 443]
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
All packages are up to date.
W: Failed to fetch https://199.232.170.132/debian/dists/bookworm/InRelease  Certificate verification failed: The certificate is NOT trusted. The name in the certificate does not match the expected.  Could not handshake: Error in the certificate verification. [IP: 199.232.170.132 443]
W: Some index files failed to download. They have been ignored, or old ones used instead.

Then, could you test with a non-Debian mirror (taken from Debian Mirrors (worldwide), don't hesitate to test other mirrors):

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deb https://ftp.u-strasbg.fr/debian/ bookworm main

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#> LANG="C" apt -o "Debug::Acquire::https=1" -o "Debug::Acquire::http=1" -o "Debug::Acquire::ftp=1" update

Then test with http instead of https:

Code: Select all

deb http://deb.debian.org/debian bookworm main

Finally, could you please paste the output of

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$> apt-config dump

[Probzx]

Hello Probzx,
Thanks for updating your topic.

I made a test with a live CD on my VM and I did not find any DNS problem.

Is this VM hosted on the problematic system or on another system on the same network?

Could you please test with only this in the sources.list of the problematic system:

Code: Select all

deb https://199.232.170.132/debian/ bookworm main

This triggers an error, but this error shows an handshake attempt on my system:

Code: Select all

#> apt update
Ign:1 https://199.232.170.132/debian bookworm InRelease
Ign:1 https://199.232.170.132/debian bookworm InRelease
Ign:1 https://199.232.170.132/debian bookworm InRelease
Err:1 https://199.232.170.132/debian bookworm InRelease
  Certificate verification failed: The certificate is NOT trusted. The name in the certificate does not match the expected.  Could not handshake: Error in the certificate verification. [IP: 199.232.170.132 443]
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
All packages are up to date.
W: Failed to fetch https://199.232.170.132/debian/dists/bookworm/InRelease  Certificate verification failed: The certificate is NOT trusted. The name in the certificate does not match the expected.  Could not handshake: Error in the certificate verification. [IP: 199.232.170.132 443]
W: Some index files failed to download. They have been ignored, or old ones used instead.

Then, could you test with a non-Debian mirror (taken from Debian Mirrors (worldwide), don't hesitate to test other mirrors):

Code: Select all

deb https://ftp.u-strasbg.fr/debian/ bookworm main

Code: Select all

#> LANG="C" apt -o "Debug::Acquire::https=1" -o "Debug::Acquire::http=1" -o "Debug::Acquire::ftp=1" update

Then test with http instead of https:

Code: Select all

deb http://deb.debian.org/debian bookworm main

Finally, could you please paste the output of

Code: Select all

$> apt-config dump

Thansk for your help.
I try both on the same VM and on another VM in the same network.

Here is the ouput of the apt update with only "deb https://199.232.170.132/debian/ bookworm main" in sources.list.

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Ign:1 https://199.232.170.132/debian bookworm InRelease
Ign:1 https://199.232.170.132/debian bookworm InRelease
Ign:1 https://199.232.170.132/debian bookworm InRelease
Err:1 https://199.232.170.132/debian bookworm InRelease
  Certificate verification failed: The certificate is NOT trusted. The certificate issuer is unknown. The name in the certificate does not match the expected.  Could not handshake: Error in the certificate verification. [IP: 199.232.170.132 443]
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
All packages are up to date.
W: https://199.232.170.132/debian/dists/bookworm/InRelease: No system certificates available. Try installing ca-certificates.
W: https://199.232.170.132/debian/dists/bookworm/InRelease: No system certificates available. Try installing ca-certificates.
W: https://199.232.170.132/debian/dists/bookworm/InRelease: No system certificates available. Try installing ca-certificates.
W: https://199.232.170.132/debian/dists/bookworm/InRelease: No system certificates available. Try installing ca-certificates.
W: Failed to fetch https://199.232.170.132/debian/dists/bookworm/InRelease  Certificate verification failed: The certificate is NOT trusted. The certificate issuer is unknown. The name in the certificate does not match the expected.  Could not handshake: Error in the certificate verification. [IP: 199.232.170.132 443]
W: Some index files failed to download. They have been ignored, or old ones used instead.

Here is the ouput with the Strasbourg rep :
I also try with http insted of https but I don't notice any change.

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Ign:1 https://ftp.u-strasbg.fr/debian bookworm InRelease
Ign:1 https://ftp.u-strasbg.fr/debian bookworm InRelease
Ign:1 https://ftp.u-strasbg.fr/debian bookworm InRelease
Err:1 https://ftp.u-strasbg.fr/debian bookworm InRelease
  Temporary failure resolving 'ftp.u-strasbg.fr'
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
All packages are up to date.
W: Failed to fetch https://ftp.u-strasbg.fr/debian/dists/bookworm/InRelease  Temporary failure resolving 'ftp.u-strasbg.fr'
W: Some index files failed to download. They have been ignored, or old ones used instead.

Now, here is the output of "apt-config dump" :

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APT "";
APT::Architecture "amd64";
APT::Build-Essential "";
APT::Build-Essential:: "build-essential";
APT::Install-Recommends "1";
APT::Install-Suggests "0";
APT::Sandbox "";
APT::Sandbox::User "_apt";
APT::Authentication "";
APT::Authentication::TrustCDROM "true";
APT::NeverAutoRemove "";
APT::NeverAutoRemove:: "^firmware-linux.*";
APT::NeverAutoRemove:: "^linux-firmware$";
APT::NeverAutoRemove:: "^linux-image-[a-z0-9]*$";
APT::NeverAutoRemove:: "^linux-image-[a-z0-9]*-[a-z0-9]*$";
APT::VersionedKernelPackages "";
APT::VersionedKernelPackages:: "linux-.*";
APT::VersionedKernelPackages:: "kfreebsd-.*";
APT::VersionedKernelPackages:: "gnumach-.*";
APT::VersionedKernelPackages:: ".*-modules";
APT::VersionedKernelPackages:: ".*-kernel";
APT::Never-MarkAuto-Sections "";
APT::Never-MarkAuto-Sections:: "metapackages";
APT::Never-MarkAuto-Sections:: "tasks";
APT::Move-Autobit-Sections "";
APT::Move-Autobit-Sections:: "oldlibs";
APT::Update "";
APT::Update::Post-Invoke-Success "";
APT::Update::Post-Invoke-Success:: "/usr/bin/test -e /usr/share/dbus-1/system-services/org.freedesktop.PackageKit.service && /usr/bin/test -S /var/run/dbus/system_bus_socket && /usr/bin/gdbus call --system --dest org.freedesktop.PackageKit --object-path /org/freedesktop/PackageKit --timeout 4 --method org.freedesktop.PackageKit.StateHasChanged cache-update > /dev/null; /bin/echo > /dev/null";
APT::Update::Post-Invoke-Success:: "if /usr/bin/test -w /var/cache/swcatalog -a -e /usr/bin/appstreamcli; then appstreamcli refresh --source=os > /dev/null || true; fi";
APT::Architectures "";
APT::Architectures:: "amd64";
APT::Compressor "";
APT::Compressor::. "";
APT::Compressor::.::Name ".";
APT::Compressor::.::Extension "";
APT::Compressor::.::Binary "";
APT::Compressor::.::Cost "0";
APT::Compressor::zstd "";
APT::Compressor::zstd::Name "zstd";
APT::Compressor::zstd::Extension ".zst";
APT::Compressor::zstd::Binary "zstd";
APT::Compressor::zstd::Cost "60";
APT::Compressor::zstd::CompressArg "";
APT::Compressor::zstd::CompressArg:: "-19";
APT::Compressor::zstd::UncompressArg "";
APT::Compressor::zstd::UncompressArg:: "-d";
APT::Compressor::lz4 "";
APT::Compressor::lz4::Name "lz4";
APT::Compressor::lz4::Extension ".lz4";
APT::Compressor::lz4::Binary "false";
APT::Compressor::lz4::Cost "50";
APT::Compressor::gzip "";
APT::Compressor::gzip::Name "gzip";
APT::Compressor::gzip::Extension ".gz";
APT::Compressor::gzip::Binary "gzip";
APT::Compressor::gzip::Cost "100";
APT::Compressor::gzip::CompressArg "";
APT::Compressor::gzip::CompressArg:: "-6n";
APT::Compressor::gzip::UncompressArg "";
APT::Compressor::gzip::UncompressArg:: "-d";
APT::Compressor::xz "";
APT::Compressor::xz::Name "xz";
APT::Compressor::xz::Extension ".xz";
APT::Compressor::xz::Binary "xz";
APT::Compressor::xz::Cost "200";
APT::Compressor::xz::CompressArg "";
APT::Compressor::xz::CompressArg:: "-6";
APT::Compressor::xz::UncompressArg "";
APT::Compressor::xz::UncompressArg:: "-d";
APT::Compressor::bzip2 "";
APT::Compressor::bzip2::Name "bzip2";
APT::Compressor::bzip2::Extension ".bz2";
APT::Compressor::bzip2::Binary "bzip2";
APT::Compressor::bzip2::Cost "300";
APT::Compressor::bzip2::CompressArg "";
APT::Compressor::bzip2::CompressArg:: "-6";
APT::Compressor::bzip2::UncompressArg "";
APT::Compressor::bzip2::UncompressArg:: "-d";
APT::Compressor::lzma "";
APT::Compressor::lzma::Name "lzma";
APT::Compressor::lzma::Extension ".lzma";
APT::Compressor::lzma::Binary "xz";
APT::Compressor::lzma::Cost "400";
APT::Compressor::lzma::CompressArg "";
APT::Compressor::lzma::CompressArg:: "--format=lzma";
APT::Compressor::lzma::CompressArg:: "-6";
APT::Compressor::lzma::UncompressArg "";
APT::Compressor::lzma::UncompressArg:: "--format=lzma";
APT::Compressor::lzma::UncompressArg:: "-d";
Dir "/";
Dir::State "var/lib/apt";
Dir::State::lists "lists/";
Dir::State::cdroms "cdroms.list";
Dir::State::extended_states "extended_states";
Dir::State::status "/var/lib/dpkg/status";
Dir::Cache "var/cache/apt";
Dir::Cache::archives "archives/";
Dir::Cache::srcpkgcache "srcpkgcache.bin";
Dir::Cache::pkgcache "pkgcache.bin";
Dir::Etc "etc/apt";
Dir::Etc::sourcelist "sources.list";
Dir::Etc::sourceparts "sources.list.d";
Dir::Etc::main "apt.conf";
Dir::Etc::netrc "auth.conf";
Dir::Etc::netrcparts "auth.conf.d";
Dir::Etc::parts "apt.conf.d";
Dir::Etc::preferences "preferences";
Dir::Etc::preferencesparts "preferences.d";
Dir::Etc::trusted "trusted.gpg";
Dir::Etc::trustedparts "trusted.gpg.d";
Dir::Etc::apt-listchanges-main "listchanges.conf";
Dir::Etc::apt-listchanges-parts "listchanges.conf.d";
Dir::Bin "";
Dir::Bin::methods "/usr/lib/apt/methods";
Dir::Bin::solvers "";
Dir::Bin::solvers:: "/usr/lib/apt/solvers";
Dir::Bin::planners "";
Dir::Bin::planners:: "/usr/lib/apt/planners";
Dir::Bin::dpkg "/usr/bin/dpkg";
Dir::Bin::gzip "/bin/gzip";
Dir::Bin::bzip2 "/bin/bzip2";
Dir::Bin::xz "/usr/bin/xz";
Dir::Bin::lz4 "/usr/bin/lz4";
Dir::Bin::zstd "/usr/bin/zstd";
Dir::Bin::lzma "/usr/bin/xz";
Dir::Media "";
Dir::Media::MountPath "/media/cdrom";
Dir::Log "var/log/apt";
Dir::Log::Terminal "term.log";
Dir::Log::History "history.log";
Dir::Log::Planner "eipp.log.xz";
Dir::Ignore-Files-Silently "";
Dir::Ignore-Files-Silently:: "~$";
Dir::Ignore-Files-Silently:: "\.disabled$";
Dir::Ignore-Files-Silently:: "\.bak$";
Dir::Ignore-Files-Silently:: "\.dpkg-[a-z]+$";
Dir::Ignore-Files-Silently:: "\.ucf-[a-z]+$";
Dir::Ignore-Files-Silently:: "\.save$";
Dir::Ignore-Files-Silently:: "\.orig$";
Dir::Ignore-Files-Silently:: "\.distUpgrade$";
Acquire "";
Acquire::AllowInsecureRepositories "0";
Acquire::AllowWeakRepositories "0";
Acquire::AllowDowngradeToInsecureRepositories "0";
Acquire::cdrom "";
Acquire::cdrom::mount "/media/cdrom";
Acquire::IndexTargets "";
Acquire::IndexTargets::deb "";
Acquire::IndexTargets::deb::Packages "";
Acquire::IndexTargets::deb::Packages::MetaKey "$(COMPONENT)/binary-$(ARCHITECTURE)/Packages";
Acquire::IndexTargets::deb::Packages::flatMetaKey "Packages";
Acquire::IndexTargets::deb::Packages::ShortDescription "Packages";
Acquire::IndexTargets::deb::Packages::Description "$(RELEASE)/$(COMPONENT) $(ARCHITECTURE) Packages";
Acquire::IndexTargets::deb::Packages::flatDescription "$(RELEASE) Packages";
Acquire::IndexTargets::deb::Packages::Optional "0";
Acquire::IndexTargets::deb::Translations "";
Acquire::IndexTargets::deb::Translations::MetaKey "$(COMPONENT)/i18n/Translation-$(LANGUAGE)";
Acquire::IndexTargets::deb::Translations::flatMetaKey "$(LANGUAGE)";
Acquire::IndexTargets::deb::Translations::ShortDescription "Translation-$(LANGUAGE)";
Acquire::IndexTargets::deb::Translations::Description "$(RELEASE)/$(COMPONENT) Translation-$(LANGUAGE)";
Acquire::IndexTargets::deb::Translations::flatDescription "$(RELEASE) Translation-$(LANGUAGE)";
Acquire::IndexTargets::deb::DEP-11 "";
Acquire::IndexTargets::deb::DEP-11::MetaKey "$(COMPONENT)/dep11/Components-$(NATIVE_ARCHITECTURE).yml";
Acquire::IndexTargets::deb::DEP-11::ShortDescription "Components-$(NATIVE_ARCHITECTURE)";
Acquire::IndexTargets::deb::DEP-11::Description "$(RELEASE)/$(COMPONENT) $(NATIVE_ARCHITECTURE) DEP-11 Metadata";
Acquire::IndexTargets::deb::DEP-11::KeepCompressed "true";
Acquire::IndexTargets::deb::DEP-11::KeepCompressedAs "gz";
Acquire::IndexTargets::deb::DEP-11-icons-small "";
Acquire::IndexTargets::deb::DEP-11-icons-small::MetaKey "$(COMPONENT)/dep11/icons-48x48.tar";
Acquire::IndexTargets::deb::DEP-11-icons-small::ShortDescription "icons-48x48";
Acquire::IndexTargets::deb::DEP-11-icons-small::Description "$(RELEASE)/$(COMPONENT) DEP-11 48x48 Icons";
Acquire::IndexTargets::deb::DEP-11-icons-small::KeepCompressed "true";
Acquire::IndexTargets::deb::DEP-11-icons-small::KeepCompressedAs "gz";
Acquire::IndexTargets::deb::DEP-11-icons-small::DefaultEnabled "false";
Acquire::IndexTargets::deb::DEP-11-icons "";
Acquire::IndexTargets::deb::DEP-11-icons::MetaKey "$(COMPONENT)/dep11/icons-64x64.tar";
Acquire::IndexTargets::deb::DEP-11-icons::ShortDescription "icons-64x64";
Acquire::IndexTargets::deb::DEP-11-icons::Description "$(RELEASE)/$(COMPONENT) DEP-11 64x64 Icons";
Acquire::IndexTargets::deb::DEP-11-icons::KeepCompressed "true";
Acquire::IndexTargets::deb::DEP-11-icons::KeepCompressedAs "gz";
Acquire::IndexTargets::deb::DEP-11-icons::DefaultEnabled "false";
Acquire::IndexTargets::deb::DEP-11-icons-hidpi "";
Acquire::IndexTargets::deb::DEP-11-icons-hidpi::MetaKey "$(COMPONENT)/dep11/icons-64x64@2.tar";
Acquire::IndexTargets::deb::DEP-11-icons-hidpi::ShortDescription "icons-64x64@2";
Acquire::IndexTargets::deb::DEP-11-icons-hidpi::Description "$(RELEASE)/$(COMPONENT) DEP-11 64x64@2 Icons";
Acquire::IndexTargets::deb::DEP-11-icons-hidpi::KeepCompressed "true";
Acquire::IndexTargets::deb::DEP-11-icons-hidpi::KeepCompressedAs "gz";
Acquire::IndexTargets::deb::DEP-11-icons-hidpi::DefaultEnabled "false";
Acquire::IndexTargets::deb::DEP-11-icons-large "";
Acquire::IndexTargets::deb::DEP-11-icons-large::MetaKey "$(COMPONENT)/dep11/icons-128x128.tar";
Acquire::IndexTargets::deb::DEP-11-icons-large::ShortDescription "icons-128x128";
Acquire::IndexTargets::deb::DEP-11-icons-large::Description "$(RELEASE)/$(COMPONENT) DEP-11 128x128 Icons";
Acquire::IndexTargets::deb::DEP-11-icons-large::KeepCompressed "true";
Acquire::IndexTargets::deb::DEP-11-icons-large::KeepCompressedAs "gz";
Acquire::IndexTargets::deb::DEP-11-icons-large::DefaultEnabled "false";
Acquire::IndexTargets::deb::DEP-11-icons-large-hidpi "";
Acquire::IndexTargets::deb::DEP-11-icons-large-hidpi::MetaKey "$(COMPONENT)/dep11/icons-128x128@2.tar";
Acquire::IndexTargets::deb::DEP-11-icons-large-hidpi::ShortDescription "icons-128x128@2";
Acquire::IndexTargets::deb::DEP-11-icons-large-hidpi::Description "$(RELEASE)/$(COMPONENT) DEP-11 128x128@2 Icons";
Acquire::IndexTargets::deb::DEP-11-icons-large-hidpi::KeepCompressed "true";
Acquire::IndexTargets::deb::DEP-11-icons-large-hidpi::KeepCompressedAs "gz";
Acquire::IndexTargets::deb::DEP-11-icons-large-hidpi::DefaultEnabled "false";
Acquire::IndexTargets::deb-src "";
Acquire::IndexTargets::deb-src::Sources "";
Acquire::IndexTargets::deb-src::Sources::MetaKey "$(COMPONENT)/source/Sources";
Acquire::IndexTargets::deb-src::Sources::flatMetaKey "Sources";
Acquire::IndexTargets::deb-src::Sources::ShortDescription "Sources";
Acquire::IndexTargets::deb-src::Sources::Description "$(RELEASE)/$(COMPONENT) Sources";
Acquire::IndexTargets::deb-src::Sources::flatDescription "$(RELEASE) Sources";
Acquire::IndexTargets::deb-src::Sources::Optional "0";
Acquire::Changelogs "";
Acquire::Changelogs::URI "";
Acquire::Changelogs::URI::Origin "";
Acquire::Changelogs::URI::Origin::Debian "https://metadata.ftp-master.debian.org/changelogs/@CHANGEPATH@_changelog";
Acquire::Changelogs::URI::Origin::Ubuntu "https://changelogs.ubuntu.com/changelogs/pool/@CHANGEPATH@/changelog";
Acquire::Changelogs::AlwaysOnline "";
Acquire::Changelogs::AlwaysOnline::Origin "";
Acquire::Changelogs::AlwaysOnline::Origin::Ubuntu "1";
Acquire::Languages "";
Acquire::Languages:: "fr_FR";
Acquire::Languages:: "fr";
Acquire::Languages:: "en";
Acquire::Languages:: "none";
Acquire::CompressionTypes "";
Acquire::CompressionTypes::xz "xz";
Acquire::CompressionTypes::bz2 "bzip2";
Acquire::CompressionTypes::lzma "lzma";
Acquire::CompressionTypes::gz "gzip";
Acquire::CompressionTypes::lz4 "lz4";
Acquire::CompressionTypes::zst "zstd";
DPkg "";
DPkg::Path "/usr/sbin:/usr/bin:/sbin:/bin";
DPkg::Pre-Install-Pkgs "";
DPkg::Pre-Install-Pkgs:: "/usr/bin/apt-listchanges --apt || test $? -lt 10";
DPkg::Pre-Install-Pkgs:: "/usr/sbin/dpkg-preconfigure --apt || true";
DPkg::Tools "";
DPkg::Tools::Options "";
DPkg::Tools::Options::/usr/bin/apt-listchanges "";
DPkg::Tools::Options::/usr/bin/apt-listchanges::Version "2";
DPkg::Tools::Options::/usr/bin/apt-listchanges::InfoFD "20";
DPkg::Post-Invoke "";
DPkg::Post-Invoke:: "/usr/bin/test -e /usr/share/dbus-1/system-services/org.freedesktop.PackageKit.service && /usr/bin/test -S /var/run/dbus/system_bus_socket && /usr/bin/gdbus call --system --dest org.freedesktop.PackageKit --object-path /org/freedesktop/PackageKit --timeout 4 --method org.freedesktop.PackageKit.StateHasChanged cache-update > /dev/null; /bin/echo > /dev/null";
Binary "apt-config";
Binary::apt "";
Binary::apt::APT "";
Binary::apt::APT::Color "1";
Binary::apt::APT::Cache "";
Binary::apt::APT::Cache::Show "";
Binary::apt::APT::Cache::Show::Version "2";
Binary::apt::APT::Cache::AllVersions "0";
Binary::apt::APT::Cache::ShowVirtuals "1";
Binary::apt::APT::Cache::Search "";
Binary::apt::APT::Cache::Search::Version "2";
Binary::apt::APT::Cache::ShowDependencyType "1";
Binary::apt::APT::Cache::ShowVersion "1";
Binary::apt::APT::Get "";
Binary::apt::APT::Get::Upgrade-Allow-New "1";
Binary::apt::APT::Get::Update "";
Binary::apt::APT::Get::Update::InteractiveReleaseInfoChanges "1";
Binary::apt::APT::Cmd "";
Binary::apt::APT::Cmd::Show-Update-Stats "1";
Binary::apt::APT::Cmd::Pattern-Only "1";
Binary::apt::APT::Keep-Downloaded-Packages "0";
Binary::apt::DPkg "";
Binary::apt::DPkg::Progress-Fancy "1";
Binary::apt::DPkg::Lock "";
Binary::apt::DPkg::Lock::Timeout "-1";
CommandLine "";
CommandLine::AsString "apt-config dump";

[fabien]

Thanks.

I try both on the same VM and on another VM in the same network.

If I understand correctly, your problematic system is a VM? If so, what is the host system? Does this host have a firewall? Any unusual network features?
Same for your problematic system. Firewall? "Unusual" network features? (like dnsmasq or bind9)
Do you remember when this first happened? Do you have any memories of an event that you could connect to this? (Any changes in your system? A crash? A full file system?)
Have you checked the logs for clues?
Sorry to ask far-fetched questions (since your network seems OK), but it's better to check.

I have some more tests. Could you please post the output of

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#> dpkg --verify

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$> apt policy ca-certificates

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$> md5sum /etc/apt/trusted.gpg{,.d/*}

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$> ls -ld /tmp/ /var/tmp/

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$> df -h; df -i

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#> apt-get check

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#> apt -o "Acquire::ForceIPv4=1" update

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#> apt -o "Acquire::ForceIPv6=1" update

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$> mkdir /tmp/aptdwnldtest/; cd /tmp/aptdwnldtest/
$> apt -o "Debug::Acquire::https=1" -o "Debug::Acquire::http=1" -o "Debug::Acquire::ftp=1" download hello
$> wget https://deb.debian.org/debian/pool/main/h/hello/hello_2.10-3_amd64.deb
$> rm /tmp/aptdwnldtest/*      ### <-- because apt does not attempt a new download if the file exists

Is aptitude installed? If so, is its behaviour the same?

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#> aptitude update