I'm using my home Synology NAS to run Docker containers with various services and APIs that I use locally in my network. One of my containers is hosted on the GitHub Container Registry, which is not supported in the NAS GUI, so I had to use SSH to authenticate to this registry and download Docker images manually.

Except for the annoying fact that every sudo required me to re-enter my admin password, this worked fine. Until it didn't. One day I started getting: Sorry, try again. when running any sudo command and entering the right password. Google didn't help much, but it inspired me to get to the solution that I finally used.

There's a trick that allows running any script as root on the NAS, using Task Scheduler: Control Panel -> Task Scheduler -> Create -> Scheduled Task -> User-defined script -> Uncheck Enabled -> Task Settings -> Fill User-defined script -> OK -> Run.

I used this method to copy the sudoers file to a shared folder ("systemshare"):

cp /etc/sudoers /volume1/systemshare/sudoers

Then I downloaded the file and added just one line:

# ... original sudoers content ...
#
myownadminuser ALL=(ALL) NOPASSWD: ALL

(In reality, "myownadminuser" is the actual username of my main admin account.)

And copied it back, using another "scheduled" task:

cp /volume1/systemshare/sudoers /etc/sudoers

This removed the annoyance of having to re-enter the password every time I wanted to do privileged operations with my administrator account, and also allowed me to sudo again.

Does this survive the next Synology update? I don't know yet... There's always a risk with these things that some automated proces will restore system files to their original/desired state. We'll see.