No need to copy the private key, in one of my PB's(sub ~40secs) after getting the RSA PRIVATE KEY
clear ctrl+C
save the file automatically in nano pvtb16.key
exit quickly using ctrl+X
then chmod 400 pvtb16.key
and get into the bandit 17 level's localhost port with the private key using ssh -oHostKeyAlgorithms=+ssh-dss -i pvtb16.key bandit17@bandit localhost -p 2220
then enter yes
when asked about fingerprints. Ta dah!