Problem:

• Product Name: VisiBroker for C
• Product Version: 7.0
• Product Component: Core ORB
• Platform/OS Version: Unix/Linux

How VisiBroker determines IP address from given hostname.

Resolution:

Basically, in a multi-homed machine, which network interface will VisiBroker bind to when you configure this property "vbroker.se.iiop_tp.host=hostname"

VisiBroker uses the system call getaddrinfo to get all the network addresses bound to the network interfaces. The IP address is mapped from a variety of sources:

1. /etc/hosts
2. DNS configured through /etc/resolv.conf
3. NIS
   
   

getaddrinfo system call has a specific order in which it resolves addresses. It checks the /etc/nsswitch.conf file for the order:

hosts: files nis dns

the setting above indicates the order is /etc/hosts, NIS and DNS.

For /etc/hosts, the first matched hostname's IP address will be used if there are more than one host names matched in it.

Assume contents of /etc/hosts was:

127.0.0.1 localhost.localdomain localhost
#
123.456.789.1 host_one
123.456.789.2 host_two
123.456.789.3 host_three
#
987.654.321.1 host_one
987.654.321.1 host_two
987.654.321.1 host_three
#
...

and if the property "vbroker.se.iiop_tp.host=host_one" set to VisiBroker's server, it will listen on this address: "123.456.789.1" when /etc/nsswitch.conf was set as above.

Author:Naoki Kawasumi