If the computers are on an internal network you can allow them access based on interface ie: eth1 using the -i flag ie:
Code:
iptables -A INPUT -i eth1 -j ALLOW
If you must connect over the internet, then you can allow based on source address ie: computers that you want to allow to connect:
Code:
iptables -A INPUT -p tcp -s 192.168.5.2 -j ALLOW
If you want to allow anyone to connect, you can allow a range of ports (that your service run under) ie:
Code:
iptables -A INPUT -p tcp --dport 1024:1124 -j ALLOW
This will allow all conections to ports 1024-1124. This is not very secure however. Try to discover what range of ports your server is running on, better yet, try to bind it to a single port....