PostUp/PreUp/PostDown/PreDown Dangerous?

Andy Dorman adorman at
Fri Jun 22 16:07:43 CEST 2018

On 6/21/18 8:41 PM, Jason A. Donenfeld wrote:
> So, the question we need to ask is whether this problem is important
> enough that these useful features should be_removed_? Or if there's a
> way to make them safer? Or if it just doesn't matter that much and we
> shouldn't do anything.

We use wg-quick with PostUp/PostDown/PreUp/PreDown and would prefer that 
feature be retained.

However, looking ahead I believe Wireguard's speed, simplicity, and 
simple, straightforward configuration and operation is going to attract 
marginally competent amateur users that definitely do not qualify as a 
system or network admin.

So, while it should be obvious, it wouldn't hurt to add a short warning 
(in bold) to the wg-quick man page that lets these "amateur" users know 
of the potential danger.  Something along the lines of "Using a config 
written by someone else that you do not understand and have not vetted 
for security is stupid and can be dangerous. For example, the 
PostUp/PostDown/PreUp/PreDown commands can be used to enable malicious 
code.  So always be certain your configuration and the code it executes 
does only what you expect."

Sincere regards,

Andy Dorman
Ironic Design, Inc.

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