You're right, but changing the 'HOST' in tnsnames.ora and listener.ora
still doesn't allow the connection to be made despite the listener
service starting without error in all cases. Although I have used (a
bit) Linux and Oracle, I am new to setting both of them up so I may
just be overlooking some parameter change or something.

>From fresh error-free Linux & Oracle installations, what are the steps
I need to take to make this machine accept JDBC connections? I am
hoping someone knows a good tutorial; I have looked at many but they
all explain how to install Linux/Oracle or how to use JDBC while none I
have seen explain the part in the middle about getting this connection
to work.

Thanks,
Jo