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Implementing Persistent IP Forwarding on Solaris Systems

By Michael Peters

This Tech Tip provides straightforward instructions on how to enable persistent IP forwarding on a Solaris system, for routing purposes.
Persistent IP forwarding is necessary if your system is performing network routing to alternate segments that reside on your private network.

System Requirements

• Hardware: At least two Ethernet interfaces installed on a system running the Solaris Operating System (SPARC or x86 Platform Edition)
• Software: Solaris Operating System (installed and networked)

Network Example

Configuration

The following example can be implemented on all Solaris OS Platform Editions:

HOST A

Create a start script in the /etc/rc2.d directory called S99ipforwarding (or any name you choose). Add the following text to the name, depending on your routing requirements, using this syntax format:

ndd  -set  /dev/ip  ip_forwarding  [ 1 or 2 ]

Option number 1 is used if you want IP forwarding turned on regardless of whether the Ethernet interfaces are online or not.

Option number 2 is used if you want IP forwarding turned on only if all the Ethernet interfaces are online.

Add the following entry to /etc/rc2.d/S99ipforwarding:

ndd -set /dev/ip ip_forwarding 1

Change the permissions on the /etc/rc2.d/S99ipforwarding file to 744, with root being the owner and sys being the group.

# chmod 744 /etc/rc2.d/S99ipforwarding.
# chown root /etc/rc2.d/S99ipforwarding.
# chgrp sys /etc/rc2.d/S99ipforwarding.

Basic Usage

You can verify the configuration status by issuing the command ndd ñget /dev/ip ip_forwarding on the command line as root.

The resulting output will be the current state of ip_forwarding 1, 2, or 0.

Questions?

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