Problem with apt-ntop-stable behind authenticated proxy

[gabviv73]

Environment:

• OS name: Ubuntu
• OS version: 20.04
• Architecture: amd64
• ntopng version/revision: 6.0.231116 [Enterprise/Professional build]

What happened: Upgrading to ntop 6 the package can't be fully installed because getting of the gpgp key fails.

The package installation fails with:

root@nbox:/etc/nprobe# apt install -f                                                                                                      
Reading package lists... Done
Building dependency tree       
Reading state information... Done
0 upgraded, 0 newly installed, 0 to remove and 24 not upgraded.
1 not fully installed or removed.
After this operation, 0 B of additional disk space will be used.
Setting up apt-ntop-stable (2.10-26) ...
Installing ntop GPG key [using proxy http://MyUsername:[email protected]:80]. Please wait...
gpg: keyserver receive failed: General error
dpkg: error processing package apt-ntop-stable (--configure):
 installed apt-ntop-stable package post-installation script subprocess returned error exit status 2
Errors were encountered while processing:
 apt-ntop-stable
E: Sub-process /usr/bin/dpkg returned an error code (1)

How did you reproduce it? apt install -f

The installation script tries to get the key using hkps:// in the --keyserver url.

Manually removing hkps:// from the --keyserver url works:

gpg --keyserver-options http-proxy="http://MyUsername:[email protected]:80" --no-default-keyring --keyring /usr/share/keyrings/ntop-archive-keyring.gpg --keyserver keyserver.ubuntu.com --recv-keys 

Manually installing the key like this does not solve the problem, the post-install script does not check if the key is already installed.