The host system is Linux Debian Stretch (9 / testing).
The Bitcoin Core package for Linux I have just downloaded and verified and installed.
I have created the following file:
/home/myUsername/.bitcoin/bitcoin.conf
With contents:
listen=1
server=1
rpcuser=myUsername
rpcpassword=myPassword
rpcport=8332
rpcconnect=127.0.0.1
Then I have punched the following holes to my firewall:
sudo iptables -A INPUT -p tcp -m tcp --dport 8333 -m comment --comment "Bitcoin Listen" -j ACCEPT
sudo iptables -A INPUT -p tcp -m tcp --dport 8332 -m comment --comment "Bitcoin RPC" -j ACCEPT
And forwarded the 8333 port from my router to the server.
I am unsure whether the second hole is necessary for RPC connections, but that's not the question now.
If I now run the following command as my regular user:
bitcoind -daemon -datadir=/raid1a/bitcoind/
It says:
Bitcoin server starting
I wait for a few minutes for it to initialize and then invoke:
bitcoin-cli getinfo
With the result:
error: incorrect rpcuser or rpcpassword (authorization failed)
I have a very long and complex password, could that be the pickle?
The debug log says only:
ThreadRPCServer incorrect password attempt from 127.0.0.1:someport