Specifications

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VMware GSX Server Virtual Machine Guide
forwarding is turned on. To turn it off, right-click the icon and disable Routing and
Remote Access. A red dot appears, indicating that IP forwarding is disabled.
Linux Hosts
If you find packets leaking out of a host-only network on a Linux host computer, check
to see if forwarding has mistakenly been enabled on the host machine. If it is enabled,
disable it.
For many Linux systems, disable forwarding by writing a 0 (zero) to the special file
/proc/sys/net/ipv4/ip_forward. As root, enter this command:
echo 0 > /proc/sys/net/ipv4/ip_forward
Other Linux systems have a system configuration option that you can set. The method
depends on your Linux distribution. You may use a control panel, specify a setting at
the time you compile your kernel or possibly enter a specification when you boot
your system. Consult your operating system documentation for details on the method
to use with your particular distribution.
Using Filtering
If the host computer has multiple network adapters, it may be intentionally
configured to do IP forwarding. In this case, you do not want to disable forwarding. To
avoid packet leakage, you must enable a packet filtering facility and specify that
packets from the host-only network should not be sent outside the host computer.
Consult your operating system documentation for details on how to configure packet
filtering.
Leaks from a Virtual Machine
Virtual machines may leak packets, as well. For example, if you use dial-up networking
support in a virtual machine and packet forwarding is enabled, host-only network
traffic may leak out through the dial-up connection.
To prevent the leakage, be sure packet forwarding is disabled in your guest operating
system.