Hello. The problem is not in the connecting logic, but in the extraction of the users from the config file. To suggest solution to this we need to see your config extraction code.

As an exercise, I have assumed the config file is not extracted automatically from an ssh method.

Untested

#/usr/bin/perl -T

use strict;
use warnings;

my( $index_of_host, %HOSTLIST );

OLOOP: while(<DATA>){

 s/^\s*// , s/\s*$//; # eradicate outer whitespace
 next OLOOP until m/^Host\s+(\w+)$/;
 # untaint $1
 $index_of_host = $1;

  ILOOP: while(defined $index_of_host && my $line = <DATA>){

    $line =~ s/^\s*//; # eradicate inner outer whitespace
    $line =~ s/\s*$//; 

    # assume an empty line between 'Host' lists in config file
    undef $index_of_host && last ILOOP unless $line; 

    if( $line =~ m/^hostname\s+(\w+)$/ ){
     # untaint $1;
     $hostname = $1 && next ILOOP;     
    }

    if( $line =~ m/^User\s+(\w+)$/ ){
     # untaint $1;
     push @{$HOSTLIST{$index_of_host}->{$hostname}}, $1;
    }
  } 
}

__DATA__
#hosts
Host host1 
    hostname host1.mydomain
    User user1

Host host2 
    hostname host2.mydomain
    User user1
[download]

Now your users are inside an anonymous array, keyed by the hostname, in an anonymous hash, keyed by the index of hosts. To retrieve:

foreach my $indhost( keys %HOSTLIST ){

  foreach my $hname( keys %$indhost ){

    foreach my $user ( @{ $hname } ){
  
      #host
      print $hname
      #user
      print $user    
    }
  }
}
[download]

Using a similar approach, you can optimise down the config file and potentially remove the 'index_of_hosts' level from the %HOSTLISTS hash This would make the extraction logic simpler.

# optimised config file

host1.mydomain 
user1
user2

#hostundef
#user1
#user2

host2.mydomain 
user1
user2
[download]

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