Access is allowed to, connections are allowed from. The firewall
question seems to have landed in the middle and the wording is quite
confusing as a result.
"With a firewall, you may wish to allow access to specific services on
"computer from others. Allow access to which services?"
"You can use a firewall to allow access to specific services on your
computer from other computers. Which services, if any, do you wish to
allow access to ?"
[or "To which services, if any , do you wish to allow access."
although I'm not sure this more correct form will sound correct in
en_US as it does in en_GB]
Went with your text.