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Creating a Simple Filter
Note: For detailed information on creating filters, refer to
the Tutorial on Internet Filters in your Communications Server's online
help. See the EasyServer II Installation
Instructions for more information on accessing online help.
To create simple filter that will terminate the call after 30 seconds
of idle time and allows you to check that establishment and re-establishment
of a connection is functioning correctly, enter the following:
To create a simple filter enter these commands:
Local>> CHANGE
INTERNET FILTER simple ENTRY 1 RULE "tcp accept 30"
Local>> CHANGE
INTERNET FILTER simple ENTRY 2 RULE "udp accept"
Local>> CHANGE
INTERNET FILTER simple ENTRY 3 RULE "icmp accept"
Creating the DOD Setup
Now that we have a simple filter and a dialer, we are ready to
create a DOD setup. The following commands will provide us with
such a setup:
Local>> CHANGE
INTERNET DOD dod1 DIALER isp
Local>> CHANGE
INTERNET DOD dod1 FILTER simple
Local>> CHANGE
INTERNET DOD dod1 ENABLED
You can confirm that your DOD setup is ready for operation by running
the command:
Local>> SHOW INTERNET
DOD dod1
If everything has been configured correctly, you should now see
that its status is Monitoring.
Testing the DOD Setup
Based on the configuration above, the simplest way to test the
connection is to telnet from the Communications Server to the remote
host. If possible you should also monitor the connection on another
screen. The best way to accomplish this is to have two terminals
or logins to the communications server. On the first login, run
the following command:
Local>> MONITOR
INTERNET DOD
This will allow you to watch the progress of the connection.
On the second login run the command:
Local>> TELNET
n.n.n.n
Where n.n.n.n is the IP address of the remote host, or the host
address provided in the PPP configuration for the dialer. This
command should start the connection. Once the connection is established,
login to the remote host and do nothing for at least 30 seconds.
You will see the time on the monitoring screen count down to zero,
then the connection should be disconnected if the setup is correct..
After the connection is disconnected the status of the link should return
to "Monitoring". Press <ENTER> on the telnet session,
the link should be reconnected and the telnet should remain logged in.
If this test is successful, you have established a simple filter.
The following section outlines the procedure for establishing more complex
filters.
Routing Considerations
To use a DOD connection effectively it is often necessary to add routes
to either the remote host or the Communications Server, or both.
There may be hosts at either end which you want to be able to access
through the dialup connection.
The most common route you will want to add is on the Communications
Server. This is a default route to the remote network. For
the above examples, and a remote network of, for example,
192.168.1.0, you would configure the default gateway as follows:
Local>> CHANGE
INTERNET GATEWAY 192.168.0.1 NETWORK ANY
This will allow the Communications Server and any machines connected
to the local network side of the Server to find their way to the remote
network. For a machine to understand this route, it must be capable
of processing RIP packets. Most Unix systems and Windows NT are
capable of this. Windows 95 is not. For Windows 95 systems, configure
the default gateway as either the Communications Server, or another
machine on the network that does understand routing protocols.
Similarly, for machines on the remote network to be able to access
those on the local network, other than the Communications Server itself,
a suitable route for the local network needs to be installed on and
propagated throughout the remote network. Consult your operating
system documentation on how to do this.
Bi-directional DOD
To configure a bidirectional DOD (a connection started from either
end) configure DOD as shown above, then configure a login or a dedicated
PPP/SLIP port for the remote host to connect to the local Communications
Server. Use the same network parameters for this login as for
the dialer configuration to dial out, and DOD will automatically
install the filters on the link when it is brought up.
