dnsx sometimes eats piped inputs and doesn't pipe out

[CorruptedPixl]

This issue affects at least v1.1.1 (and at least v1.1.0 too)

The issue:

When piping from subfinder to dnsx to httpx, sometimes dnsx doesn't process the piped input and quits.
dnsx also doesn't pipe out to httpx or following commands.
See below for full output logs.

Expected Behavior:

When running subfinder -d projectdiscovery.io | dnsx -v | httpx -title dnsx should process the subdomains found by subfinder and pipe the output to httpx.

Steps To Reproduce:

I am running this on a fresh Ubuntu (22.04.1 LTS) machine with go, subfinder, dnsx and httpx installed.

Running subfinder -d projectdiscovery.io | dnsx -v | httpx -title should produce an output as followed:

Correct output after a reboot

However, at times, dnsx refuses to work and produces no output after subfinder finishes.

Bugged output

Important notes

Some friends and I have noted that rebooting the machine seems to fix this for a while.

Now, since this (somehow) gets temporarily fixed after a reboot, I didn't want to create this issue as I thought it might've been a config error on my side. However after chatting with friends, having them install the tools and trying it out, this seems to be a widespread issue and I felt that it was important enough to take a look at.

I have tried to gather as much info to be able to determine the place of this issue, but there are simply too many variables which I cannot check myself. This is why I hope some people here might have a different setup and can reproduce this issue on other environments to narrow down the issue.

[zevaryx]

I'm one of the friends that tested it. Here's the system info of one of the systems I was able to reproduce it on. It may be related to multiple IPs available due to a variety of reasons (Docker in this case). This system was rebuilt very recently and only has Docker running on it

[CorruptedPixl]

I have done some more testing and can confirm that this bug occurs 100% of the time whenever I am connected to a vpn, specifically PIA in this case.

However, some of my friends weren't using a vpn and got the same issue so I'm not sure that's the cause.
Note: on windows, dnsx works regardless if the vpn is active or not.

I'm thinking maybe the dns settings of the vpn interfere with dnsx on Linux?

[CorruptedPixl]

Figured I'd also drop my system info. As you can see, when connected to the vpn there are multiple interfaces available, when disconnected there is only one.

[Mzack9999]

Probably this depends on the UDP protocol drop due to VPN (see #221). You can try with DOH if it's not possible to disable the VPN:

$ echo scanme.sh | go run . -resolver doh:https://doh.opendns.com/dns-query:get -verbose
scanme.sh