Perhaps code a bit like this:

my @services = qw(smtp http ssh); # list of services

foreach (@services) {
  # Somehow get the details for the given service on
  # the given node. Here I'm assuming the existance of
  # a function that returns the required hash.
  my %details = get_details($node, $_);

  $node->{$_} = \%details;
}
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<http://www.dave.org.uk>

"The first rule of Perl club is you don't talk about Perl club."