ntopng install on Debian Sqeeze

If you are careless enough to just follow a step-by-step tutorial like this being on a good old Squeeze you surely will end up with a failing and buggy ntopng. E.g. you won't be able to see your newly created users (users tab is totally empty: No Results Found)

Looks somewhat broken

or can not switch between your monitored interfaces. If you start ntopng from shell you may see something like this:
19/Aug/2015 13:28:28 [src/Redis.cpp:170] ERROR: ERR unknown command 'HSET' [HSET ntopng.host_labels ]
19/Aug/2015 13:28:28 [src/Redis.cpp:170] ERROR: ERR unknown command 'HSET' [HSET ntopng.host_labels ]
19/Aug/2015 13:28:30 [src/Redis.cpp:148] ERROR: ERR unknown command 'HGET'
19/Aug/2015 13:28:30 [src/Redis.cpp:148] ERROR: ERR unknown command 'HGET'
19/Aug/2015 13:28:30 [src/Redis.cpp:148] ERROR: ERR unknown command 'HGET'
19/Aug/2015 13:28:30 [src/Redis.cpp:148] ERROR: ERR unknown command 'HGET'
19/Aug/2015 13:28:36 [src/Redis.cpp:148] ERROR: ERR unknown command 'HGET'
19/Aug/2015 13:28:36 [src/Redis.cpp:148] ERROR: ERR unknown command 'HGET'
19/Aug/2015 13:28:36 [src/Redis.cpp:148] ERROR: ERR unknown command 'HGET'

This whole thing is because your Redis installation is out of date. Another nice thing in Debian Squeeze is its repositories includes Version: 2:1.2.6-1 Redis. Simply fix that with:
echo "deb http://backports.debian.org/debian-backports squeeze-backports main" >> /etc/apt/sources.list
apt-get update
apt-get -t squeeze-backports install redis-server

Now it is:
redis-server                       2:2.4.15-1~bpo60+2    
How to reset your forgotten ntopng admin password.
You might don't want to bother with compiling ntopng-2.0 packages on a simple standard Squeeze. In that case here are the x64 and x86 versions. You're welcome.