Cannot resolve localhost to an IPv6 address on ubuntu-latest (all Python versions affected) #929

cytopia · 2020-05-22T21:06:57Z

Describe the bug
As of today I am getting the following error resolving localhost to an IP address on Ubuntu latest:

[Errno -5] No address associated with hostname

The resolving process is done via Python:

socket.getaddrinfo(...)

It affects all Python versions: 2.6, 3.5, 3.6, 3.7, 3.8 pypy2 and pypy3

This has not happened a few days ago and it also does not happen on MacOS or Windows

Area for Triage:
https://github.com/cytopia/pwncat/pull/77/checks?check_run_id=700746839#step:5:2368

Question, Bug, or Feature?:
Bug

Virtual environments affected

Expected behavior
localhost is resolved to ::1 (IPv6)

Actual behavior
The following error is thrown:

[Errno -5] No address associated with hostname

https://github.com/cytopia/pwncat/pull/77/checks?check_run_id=700886122#step:5:21

Reproducible via the following Python snippet on ubuntu-latest on all available Python versions.

import socket
socket.getaddrinfo("localhost", None)

https://github.com/cytopia/pwncat/pull/77/checks?check_run_id=700886122#step:5:21

The text was updated successfully, but these errors were encountered:

cytopia · 2020-05-22T21:52:16Z

I've investigated this further and it seems like IPv6 support is simply gone: https://github.com/cytopia/pwncat/pull/77/checks?check_run_id=700886122#step:5:21

It seems to be working for IPv4, but not for IPv6 anymore.

maxim-lobanov · 2020-05-23T05:01:24Z

Probably, similar to #668

cytopia · 2020-05-23T10:11:35Z

Probably, similar to #668

I don't think so. As I wrote above, the problem started as of today (yesterday). It all worked fine before and now my builds started failing due to this.

miketimofeev · 2020-05-23T10:28:17Z

@cytopia does the same happen on Ubuntu 16? I wonder if it's related to this PR #881

cytopia · 2020-05-23T10:30:34Z

Give me a few minutes, will add pipelines for these to try it out

cytopia · 2020-05-23T10:38:51Z

Seems to be the same issue on Ubuntu 16: No IPv6 support available anymore

Ubuntu 16 (fails): https://github.com/cytopia/pwncat/runs/701818515?check_suite_focus=true#step:5:22
MacOS (success): https://github.com/cytopia/pwncat/runs/701818551?check_suite_focus=true#step:5:22
Windows (success): https://github.com/cytopia/pwncat/runs/701828359?check_suite_focus=true#step:5:28

al-cheb · 2020-05-23T11:29:16Z

@cytopia

Could you please test with step?

sudo bash -c "cat > /etc/hosts" << EOL
127.0.0.1       localhost
::1     localhost ip6-localhost ip6-loopback
EOL

cytopia · 2020-05-23T11:32:25Z

@al-cheb is there something where I can tell it for a step to only do this on Linux?

al-cheb · 2020-05-23T11:36:05Z

if [ `uname` = "Linux" ]; then
sudo bash -c "cat > /etc/hosts" << EOL
127.0.0.1       localhost
::1     localhost ip6-localhost ip6-loopback
EOL
fi

cytopia · 2020-05-23T11:59:52Z

Looks good so far. I can resolve it to IPv6 again. Will however also wait for the whole pipeline and report back here

agrobbin · 2020-05-26T16:55:51Z

@al-cheb we've started running into a very similar issue, specifically with Percy.io's image downloading functionality:

Error: getaddrinfo ENOTFOUND [foo.bar].localhost

We use .localhost as a TLD, which up until 5/22 worked just fine, but starting on 5/22 (and I believe alongside the 20200518.1 virtual env release), requests for our assets on that domain are no longer working.

I tried including your suggested change to /etc/hosts, and unfortunately still no luck. Any help here would be greatly appreciated!

al-cheb · 2020-05-26T17:30:56Z

Hello, @agrobbin
Could you please validate with step?

- name: revert
  run: | 
        sudo ln -sf /run/systemd/resolve/stub-resolv.conf /etc/resolv.conf

agrobbin · 2020-05-26T19:17:24Z

@al-cheb that line did the trick!

agrobbin · 2020-05-26T19:27:06Z

@al-cheb is this something that will be resolved in a future virtual environment release, or should we anticipate having to include this in our Actions YAML file going forward?

al-cheb · 2020-05-26T19:36:15Z

@agrobbin, Sorry for the inconvenience. We are planning to revert the #881 PR that is the root cause of this issue. Not until we roll-out a new image with a fix you should use the temporary workaround. I will provide feedback to you when we can delete the workaround. ETA: ~ 2 weeks.

agrobbin · 2020-05-26T19:37:26Z

Sounds good, @al-cheb thanks again for all of your help! In the meantime, I'll keep an eye on these issues.

al-cheb · 2020-06-10T14:47:17Z

Hello,@cytopia, @agrobbin
We have reverted the PR with the issue. Could you please validate your pipelines if the problem is still reproducing?

agrobbin · 2020-06-10T15:11:45Z

@al-cheb I just confirmed that removing our patch for this issue no longer causes resolution issues. Looks like things are fixed! Thanks so much for your help.

yidongnan · 2020-06-11T03:25:17Z

https://github.com/yidongnan/grpc-spring-boot-starter/runs/760320005?check_suite_focus=true#step:3:7

I still have this problem after deleting this patch, is there any cache here?

al-cheb · 2020-06-11T06:40:33Z

@yidongnan, Hello
Could you please try to test #929 (comment) ?

yidongnan · 2020-06-11T06:51:21Z

@al-cheb I just confirmed that removing our patch for this issue no longer causes resolution issues. Looks like things are fixed! Thanks so much for your help.

@al-cheb Using this patch will work, I read the comment saying that the patch removal is work. I thought the problem was fixed, but when I removed the patch, it found that it did not work.

This is my modification
https://github.com/yidongnan/grpc-spring-boot-starter/pull/367

al-cheb · 2020-06-11T07:16:49Z

@al-cheb I just confirmed that removing our patch for this issue no longer causes resolution issues. Looks like things are fixed! Thanks so much for your help.

@al-cheb Using this patch will work, I read the comment saying that the patch removal is work. I thought the problem was fixed, but when I removed the patch, it found that it did not work.

This is my modification
yidongnan/grpc-spring-boot-starter#367

I think we have got several issues one with resolving IPv4 localhost(revert PR fixed the issue) and the second one with IPv6.

al-cheb · 2020-06-23T14:44:22Z

Hello, @yidongnan
I can reproduce this behavior with resolving IPv6 localhost name on clean Ubuntu VMs with OS version 18.04+(Azure VM, Hyper-V). The default /etc/hosts file on Ubuntu Server 14.04+ is (e.g. for other linux distros - https://gist.github.com/ghoneycutt/e531984406b4b86ace687ea8958a6dc3#file-hosts-md):

I have created a simple test:

import java.net.InetAddress;

public class Test {
    public static void main(String[] args) throws Exception {
        InetAddress[] inetAddresses = InetAddress.getAllByName(args[0]);
        for(InetAddress inet : inetAddresses){
            System.out.println(inet);
        }
    }
}

Output:

ubuntu:~$ java -classpath . Test localhost
localhost/127.0.0.1
ubuntu:~$ java -classpath . Test ip6-localhost
ip6-localhost/0:0:0:0:0:0:0:1

Update /etc/hosts/ file and add the alias localhost for ::1:

ubuntu:~$ sed -i 's/::1 ip6-localhost ip6-loopback/::1     localhost ip6-localhost ip6-loopback/g' /etc/hosts
ubuntu:~$ java -classpath . Test localhost
localhost/127.0.0.1
localhost/0:0:0:0:0:0:0:1

We are not planning to change/update default name resolution due to unexpected behaviors for other customers.

Workaround:

Add the alias localhost for ::1 manually to the pipeline - Cannot resolve localhost to an IPv6 address on ubuntu-latest (all Python versions affected) #929 (comment)
Change localhost name to ip6-localhost or ::1 in your test
Use only 127.0.0.1 or ::1

yidongnan · 2020-06-24T02:56:15Z

We are not planning to change/update default name resolution due to unexpected behaviors for other customers.

@al-cheb Thanks for your reply, I see that ubuntu 18.04 and 14.04 have added ::1 localhost by default, so I think it’s more appropriate to be consistent with the ubuntu official. I think that only by being consistent will no unexpected behavior happen.

al-cheb · 2020-07-01T16:34:47Z

Hello, @yidongnan
Fix with alias for ::1 localhost has been deployed. Could you please check from your side?

yidongnan · 2020-07-02T02:49:05Z

@al-cheb Looks like things are fixed! Thanks so much for your help.

cytopia mentioned this issue May 22, 2020

Release 0.0.21 cytopia/pwncat#77

Merged

cytopia changed the title ~~Cannot resolve localhost to an IP address on ubuntu-latest (all Python versions affected)~~ Cannot resolve localhost to an IPv6 address on ubuntu-latest (all Python versions affected) May 22, 2020

al-cheb self-assigned this May 23, 2020

al-cheb added Area: Image administration OS: Ubuntu labels May 23, 2020

miketimofeev mentioned this issue May 26, 2020

Ubuntu 18.04 unable to resolve cognitiveservices DNS names #798

Closed

5 tasks

Darleev mentioned this issue May 27, 2020

Revert systemd-resolve workaround. #943

Merged

1 task

al-cheb added the awaiting-deployment Code complete; awaiting deployment and/or deployment in progress label May 27, 2020

al-cheb closed this as completed Jun 10, 2020

al-cheb reopened this Jun 11, 2020

al-cheb mentioned this issue Jun 25, 2020

[Ubuntu] Add localhost alias ::1 IPv6 #1107

Merged

4 tasks

al-cheb closed this as completed Jul 2, 2020

SuperSandro2000 mentioned this issue Jul 5, 2020

Add geturl connectivity unit tests ddclient/ddclient#235

Merged

andy31415 mentioned this issue Jul 10, 2020

Attempt to Re-enable the TestInetLayerDNS Unit Test project-chip/connectedhomeip#1541

Closed

pimterry mentioned this issue Sep 7, 2021

Fallback can incorrectly fail to resolve with some /etc/hosts configurations szmarczak/cacheable-lookup#42

Closed

hoffmang9 mentioned this issue Oct 20, 2021

Resolve v6 addresses Chia-Network/chia-blockchain#8861

Merged

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Cannot resolve localhost to an IPv6 address on ubuntu-latest (all Python versions affected) #929

Cannot resolve localhost to an IPv6 address on ubuntu-latest (all Python versions affected) #929

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Cannot resolve localhost to an IPv6 address on ubuntu-latest (all Python versions affected) #929

Cannot resolve localhost to an IPv6 address on ubuntu-latest (all Python versions affected) #929

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