Binding a Second IP to an Interface Card

Question

Hey All,
I need to bind a second IP address to my single network card on a Solaris 7 server. I've done this in Linux by adding an additional ifcfg-eth0 file to /etc/sysconfig/network-scripts, specifying the new IP address. With Solaris though, the new landscape has me a bit flustered. I'd very much appreciate a guide through the woods here, my flashlight is going dim...
Much Appreciated,
Chris

Answer 1

Hi Chris,
Here's a write up on this question:
Virtual Interfaces (One interface, different IPs):
Solaris TCP/IP allows multiple logical interfaces to be associated with a physical network interface. This allows a single machine to be
assigned multiple IP addresses, even though it may have only one
network interface. (see the ifconfig man page)
You can define up to 255 "logical addresses" for a given network interface on Solaris 2.x.
There is no supported method to do so on SunOS 4.1.X (Solaris 1.x)
In Solaris 2.6 you can go greater than 256 ( 0-255 ) which is configurable with NDD. The command "ndd -set /dev/ip ip_addrs_per_if 1-8192" will permit you to configure as many as your addressing structure will permit
(up to 8191 virtual hosts.)
1. Create an entry in the /etc/hosts file ( or nis host map) for each of the virtual interfaces with the hostname and IP address you want to use. Don't forget to add the hostname to /etc/hosts NIS, NIS+, and/or DNS database.
2. Create a /etc/hostname.<interface:#> file for each of the interfaces. (/etc/hostname.le0:1, hostname.le0:2, hostname.le0:3...le0:255.)
The file can contain a single line with either the ip number or hostname reference. For example, if you are using the le0 interfaces, you would create the following files:
/etc/hostname.le0:1 (do NOT use a le0:0 - same as le0 )
/etc/hostname.le0:2
and so on
This can also be done for an hme interface. You can have up to 1024 virtual interfaces under 2.5.1 This file should include the hostname or IP address for the corresponding interface.
3. If subnetting is being used, there should be an entry in the
/etc/netmasks file in the following format:
network_address netmask
The network_address should be the network address before
subnetting. For example, a class B network that is subnetted to
a Class C would have an entry such as:
157.145.0.0 255.255.255.0
4. Reboot the system
5. Verify changes with an ifconfig -a
Note: there are some bugs with third party applications/daemons that do not operate well with many virtual interfaces.
Additional Note: For Security and network isolation. You can set ip_forwarding off and ip_strict_dst_multihoming on, if you are trying to prevent access to the other interfaces.
"ndd /dev/ip ip_forwarding" Determines if the workstation will route packets.
"ndd /dev/ip ip_strict_dst_multihoming" Determines whether to use Strict Destination Multihoming. If this variable is set to True, and ip_forwarding is turned off, then the machine will not except packets destined for a different interface. RFC112
If duplicate additional local routes are added (by ifconfig) when the virtual interfaces are on same subnet, then you may need to "route delete net" on these.
A /etc/rc2.d/S99vif file can be added to ifconfig and add/delete routes, etc.
On 2.6 it may be neccessary to turn off interface groups.
To disable this feature (which is on by default) the following line
must be added to /etc/rc2.d/S69inet
ndd -set /dev/ip ip_enable_group_ifs 0
Thanks
Sujeet (Sun-DTS)