PLSSS HELP how can I set up 2 interfaces on ASTERISK

Hello I’m trying to set up an Asterisk server, and it has two interfaces one is configurated with the address 172.20.42.50 and it has an unique purpose; is to let an administrador get access to configure the Asterisk server through the web server, the other interface is in the address 172.20.42.2 and is destinated for the IP softphones,

My question is how can I Configure the server in order to only let access if the request come from the address 172.20.42.50, and reject any attempt to configure the server if it comes from the computers connected on the interface 172.20.42.2.

I’m new on this if you could make a detailed explanation it would be very helpfull. thank u =)

Sorry for my bad english, I hope u understand the problem.

in the sip.conf and iax.conf files insert a line to bind the listening address:

bindaddr = 172.20.42.2