Smartdnsblock.exe slowing down whole dns

[Roki100]

Describe the bug So basically while im (my friends as well) are connected to outline server the dns queries take around 10 seconds to complete, but after killing smartdnsblock.exe they complete instantly.

To Reproduce Just connect to the outline vpn.

Expected behavior Instant dns resolving

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Client System (please complete the following information):

• Outline Client Version 1.5.0
• Your Operating System: Windows 10

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[alalamav]

Hi @Roki100, smartdnsblock prevents the system from leaking DNS queries by blocking UDP traffic to the default interface and redirecting it through the VPN. The behavior you observe is expected: without smartdnsblock your DNS queries get sent to the default interface resolver, which is faster than routing them through Outline (hop to the proxy + encryption/decryption).

However, DNS queries over UDP should not take ~10s to resolve, even through the VPN. Do your network and server support UDP forwarding? Outline enables a DNS over TCP fallback when the network and/or server do not support UDP forwarding, so that may explain the longer resolution time.

[Roki100]

Hi @Roki100, smartdnsblock prevents the system from leaking DNS queries by blocking UDP traffic to the default interface and redirecting it through the VPN. The behavior you observe is expected: without smartdnsblock your DNS queries get sent to the default interface resolver, which is faster than routing them through Outline (hop to the proxy + encryption/decryption).

However, DNS queries over UDP should not take ~10s to resolve, even through the VPN. Do your network and server support UDP forwarding? Outline enables a DNS over TCP fallback when the network and/or server do not support UDP forwarding, so that may explain the longer resolution time.

im pretty sure both network and the server support udp forwarding, i am not sure how to check that to be 100% sure tho, however i was reading that https://supportcenter.checkpoint.com/supportcenter/portal?eventSubmit_doGoviewsolutiondetails=&solutionid=sk111657 but i am not sure if that is related, i would like to fix this issue with the resolving taking so long because our fix for now was replacing the .exe with some random .exe

edit: i did use netcat and it seems udp connection is working fine if thats what you mean 2nd edit: i forgot to mention it only happens on windows, on linux and android everything works fine

[grandsilence]

I have the same issue on Windows 10 (1803), Outline Client v1.6.0. After killing smartdnsblock process it's working instant. On Mac OS and iOS DNS working as expected well.