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NetModem Frequently Asked Questions


 

Is it possible to share a single modem connection between two clients at the same time?

Does NetModem Server support RAS (Remote Access Service) in Windows Server?

Is Active Directory required to support User Authentication?

Does NetModem support multiple modem pools?

Can I set up NetModem Client to get the next available shared modem on the Server?

Can I use NetModem Client ports for faxing through shared modems?

Can I use the same modems for dialout calls and inbound fax or data calls?

What happens when a client tries to use a modem that is already in use by another client?

When attempting to add a modem driver to the client's virtual COM port, the COM port is not listed. Why?

Can NetModem Server verify that a modem is connected and powered on before providing that COM port to a client?

Why can multiple default routes be a problem?

Why cant NetModem Client immediately report a broken network connection to the application?

Does using modems over a network affect the timing of data transmission?

When using Dial-Up Networking, why does the client PC loses access to parts of my local area network?

How can I prevent NetModem from automatically starting when Windows starts?

Why does the client's SERVER TEST report that the Modem is not detected?

Why does my application fail to connect/dial now that I am using NetModem?

Why do I encounter a failure or crash when using a Digi Acceleport Xp (2p/4p/8p/16p) serial card?

Do I need to have the same COM port numbers defined on the NetModem Client and NetModem Server?

ISA Server is blocking NetModem Traffic. How do I solve this?

How can I remotly deploy NetModem Client with pre-configured COM ports?

When Uninstalling NetModem Server, why did I get an Installer Error 1721

What version of OpenSSL does NetModem use?

Why doesn't encryption work?

 



Is it possible to share a single modem connection between two clients at the same time?

The nature of analog modems and a phone line limits any single modem to connecting to one phone number at a time, and if one application is using the modem to connect to a certain phone number, it would not be possible for another application to dial out to another phone number on that modem at same time.

However, Windows has a feature called "Internet Connection Sharing" which can allow a PC to share one internet connection with other PCs on their local network. It does not matter if the source of the internet connection is thru a Dial-Up Networking (DUN) modem connection, or a full time connection such as DSL, cable, etc. NetModem can be used to make a DUN connection, and this DUN connection could be shared just as if it had been done on a local modem.

For dialup applications other then DUN, you would need either multiple modems or a multi-modem PCI card, and you would also need multiple phone lines. NetModem Server is designed to "pool" multiple modems, so each time another user needs to dial out, the next modem in the pool is automatically assigned to them.



Does NetModem Server support RAS (Remote Access Service) in Windows Server?

If RAS / RRAS is installed on the NetModem Server PC, NetModem Server will allow modems to be pooled both by RAS (for Dial-In) and by NetModem Server (for Dial-Out). Each time a client requests a modem, NetModem Server will ask RAS if a modem is currently in use, and if RAS says its available, NetModem Server will borrow that modem from RAS, returning it to RAS's use after the client is finished with it.



Is Active Directory required to support User Authentication?

Active Directory is not required for user authentication, and you can locally authenticate on a network without a domain controller by simply defining users and groups on the NetModem Server PC. NetModem Server also supports multiple Active Directory controllers and NT4 domain controllers.

NetModem Server allows each pool of modems be individually configured for user authentication. If user authentication is enabled for a pool, only the users and groups defined in that pool properties access list will be given access.



Does NetModem support multiple modem pools?

NetModem Server allows multiple pools to be defined. Each modem pool can contain one or multiple modems, and all the modems in the pool share the same properties and security settings.



Can I set up NetModem Client to get the next available shared modem on the Modem Server?

Yes, this can be done in the NetModem Client Configuration window by setting the "Remote COM port to connect" pulldown ment to "Automatic Pooling".



Can I use NetModem Client COM ports for faxing through shared modems?

Yes, but we reccomend that you use fax modems which support Class 2 or Class 2.0 fax and the PC faxing software you are using must also be configured to use Class 2 or Class 2.0. Class 1 is timing sensitve and therefore it may not always be reliable when used over a networked modem. For more information please refer to the faxing issues page.



Can I use the same modem(s) for dialout calls and inbound fax or data calls?

NetModem allows using a modem for inbound modem data/fax calls by a client PC, but this would cause the modem to be constantly in-use by the client
that is holding the Modem port open while listening for an incoming RING, thereby preventing other clients from using this modem during that this time.


For receiving inbound DUN (Dial Up Networking) calls on the modems, you can enable Microsoft RAS (Remote Access Service) on the NetModem Server PC, allowing NetModem Server to share the modem resources with RAS. Then when a client requests a modem, NetModem Server will ask RAS if the modem is currently available, and if it is, NetModem Server will borrow the modem and return it to RAS after the client releases it.

If the Network Administrator does not want to allow the NetModem Client PC's to be able allow modem applications such as pcAnywhere to accept incoming modem calls, a pool of modems can be configured to block Dial-In. This option is found under Pool Properties in NetModem Server.



What happens when a client tries to use a modem that is already in use by another client?

When a client application attempts access a modem, but all the shared modems on the server are currently in-use by other clients (or local applications on the Server PC), the client will receive a pop-up message on their screen indicating that NetModem Server does not have any available modems. This pop-up message can be disabled in a client under the "Advanced" settings button. The client application will be told that the Modems COM port could not be opened, due to being in use by another application.



When attempting to add a modem driver to the client's virtual COM port, the COM port is not listed. Why?

Some Plug-and-Play modem drivers (Including US Robotics and Multitech external modems) will fail to see a modem attached to a virtual COM port by default. This is also true for most Software based modems (commonly called SoftModems), which look for PCI or USB hardware to be present before allowing a COM port to be selected.

Another possible reason for this is if the virtual COM port has not been configured with the correct IP address, or the "Save" button has not been clicked after setting the IP Address, thus preventing it from reaching the physical modem on the NetModem Server PC. You should verify that your NetModem Client COM port is configured properly, by going to the "NetModem Client Configuration", selecting that COM port, and run the "Test Server Connection" to verify that the modem on the server is detected.

If the test is successful, then please contact a PC Micro support engineer and provide your modem driver .INF file, and we can modify it to allow installing it on a virtual COM port. You can email the file to support@pcmicro.com. If you don't have the .INF file, then please provide the exact model number of the Modem. Note: Some mail servers do not allow sending/receiveing .INF file extentions, so before sending it to us, please rename the extention to something else such as .TXT or .IN_.



Can NetModem Server verify that a modem is connected and powered on before providing that COM port to a client?

By default NetModem Server does not check to see if there is a modem connected to one of the shared COM ports before passing that COM port to a client.

In order to enable this behavior, click on "Properties" from the NetModem Server Configuration tab, and enable the checkbox named "Reset Modem when opening port". Then click "Ok" followed by "Save Changes".

This will cause NetModem Server to send an "ATZ" initialization command to the next available modem in the pool, and it then waits for the modem to respond with an "OK" before passing that COM port to the client. If an "OK" response is not received within 1 second, it will try the next available shared COM port.



Why can multiple default routes be a problem?

NetModem Client may need to update the IPv4 routing table to ensure that it allows the NetModem Server to remain reachable. This is nessesary because a Dial-Up Networking (PPP) connection will change the IPv4 routing table to reach the DUN destination. Each time a NetModem Virtual COM port is opened, the default action is to update the routing table as needed to allow the NetModem Server to always remain reachable. If there are multiple default routes in the table, NetModem Client will use the first default route to determine a new route which might need to be added.

Problems can appear if the route table has default route(s) which are bad, for example, if the IP address listed as the gateway doesn't exist or is unreachable. If the only default route is bad, or the first one of multiple default routes are bad, it is likley you will experience a problem when creating a Dial-Up Networking conection. If NetModem Client needs to create a specific route for a NetModem Server which is on a different subnet, it will use that unreachable/non-existant gateway, which then renders the NetModem Server PC as unreachable.

NetModem Client will implement incorrect specific routes only if the routing table is misconfigured and/or reports invalid information.



Why can't NetModem Client immediately report a broken network connection to the application?

Depending on its configuration on your network, the keep-alive feature of the TCP/IP protocol takes a long time (10 to 15 minutes) to differentiate between a merely idle connection and a broken one. The TCP protocol opts to err on the side of keeping a possibly idle connection open.

To improve on this, NetModem Client and NetModem Server use a separate mechanism to detect lost connection in approximately one minute.



Does using modems over a network affect the timing of data transmission?

A small time delay (known as latency) is added when communicating over a network, compared to using a local serial port and modem. There is a small number of applications that are sensitive to latency, The most common is Class 1 fax applications. Therefore we do not reccomend using NetModem with class 1 fax applications. Most hardware-based modems support Fax Class 2 or 2.0 protocols which are not effected by latency.



When using Dial-Up Networking, why does the client PC lose access to parts of my local area network?

Dial-Up Networking will always add a new "default route" to the TCP/IP IPv4 routing table once a DUN session is started. If the local area network uses IPv4 and contains multiple subnets, and the PC connects to those subnets using a default route in the routing table, the new default route added by Dial-Up Networking will be used instead of the original one.

This results in the PC now having access only to the local subnet, because any TCP packets destined for the other subnets will be routed to the modem rather than to the network interface card.

This issue is not unique to NetModem Client, as it will also also occur on a PC using a local modem.
For more information, see the following Microsoft Knowledge Base articals:

While these KB Articles only refer to Windows NT, they also apply to all later versions of Windows.
The solution is to modify the routing table by adding a static route to the other subnets, as described in KB Article 140859.
NetModem Client has an option to update the routing table automaticly when the NetModem Server is on another subnet. This can be found under the Advanced section of the NetModem Client Configuration, and is enabled by default.


How can I prevent NetModem Server or NetModem Client from automatically starting on Windows startup?

Both NetModem Client and NetModem Server run as a Windows Service. Either Service can be stopped or even disabled by going to the Windows Control Panel under Services, and configuring the "NetModem Client" or "NetModem Server" service. It is also possible to run NetModem Server as a non-service executable.


Why does the client's SERVER TEST report that the modem is not detected?

This mindicates that when the client sent an AT command to the modem on the server, the modem failed to send back an OK response.
This could be caused by a number of reasons, such as a defective modem, or selecting a COM port in NetModem Server which does not have a modem attached to it.

If you encounter this issue, verify that your modem is working by going to the NetModem Server PC and under the Windows Control panel open "Phone and Modem", then select your modem under the "Modems" tab, and click Properties > Diagnostics > Query Modem. If the query fails to communicate with the modem, or of none of the Responses show "Success", then the modem is not functioning, or is already in use by another application or service. Contact a PC Micro support engineer for further assistance.


Why does my application fail to connect/dial now that I am using NetModem?

The 2 most common reasons are a bad phone number or a modem driver issue.

Phone Number issues:
Verify that the telephone number is entered correctly  (1+area code for long distance, any access codes you may need for an outside line such as 9 before the number.) You may also try plugging in a standard analog phone and try to dial the number to verify that the phone line supports outbound or long distance calls.

Modem driver Issues:
On the server side check that there is not more then one modem driver assigned to the COM port, byt going to Control Panel > Phone and Modem Options > Modems. If more then one modem driver is assigned to the same COM port, NetModem Server will not be able to open the port correctly.

On the client side check the installed modem drivers to make sure they match the modem which is installed on the server side. if these drivers are for a generic "Standard 56k modem" rather then being for the specific brand and model of modem(s) installed on the NetModem Server, it can cause connections to fail due to mismatched "AT" commands. Therefore it is never reccomended to use the "Standard 56k modem" driver (or a driver for a different model of modem), on the NetModem Client PC.

Some modem drivers (most commonly PCI and USB) will not install on a Client's virtual com port, because they expect to see the PCI or USB hardware present. Our support department can modify these modem drivers for you to allow you to install them.


Why do I encounter a failure or crash when using a Digi Acceleport Xp (2p/4p/8p/16p) serial card?

There are known issues with older versions of the Digi Acceleport Xp firmware, which can cause advanced modem applications to fail, hang, or crash. This has been solved in the current Digi firmware, which is a free downloadable update available from Digi's web site here: http://www.digi.com/support/productdetl.jsp?pid=1374&osvid=0&tp=2


Do I need to have the same COM port numbers defined on the NetModem Client and NetModem Server?

No. They are independent from each other.


ISA Server is blocking NetModem Traffic. How do I solve this?

Assuming NetModem Server is installed on the ISA Server PC, and the NetModem clients are on the internal network, You will need to define the following two rules in ISA Server, one for inbound traffic and one for outbound traffic:

Rule 1
  1. Create a new rule using the rules wizard
  2. Specify Internal,Localhost in 'from tab'
  3. Specify Localhost in 'to tab'.
  4. Select and add Telnet to 'protocol tab'
  5. Again on the protocol tab click PORTS and specify 6000 minimum 6000 maximum
  6. Enable the rule and APPLY the update.
Rule 2
  1. Create a new rule using the rules wizard
  2. Specify Localhost in 'from tab'
  3. Specify Internal,Localhost in 'to tab'
  4. Select and add Telnet to 'protocol tab'
  5. Again on the protocol tab click PORTS and specify 6000 minimum 6000 maximum
  6. Enable the rule and APPLY the update.


When Uninstalling NetModem Server, why did I get an Installer Error 1721?

NetModem Server version 3.33 installer was the first version to use InstallShield 2008 which can result in an install error 1721 in some rare cases. This installer error appears when trying to uninstall or upgrade to a newer version. This can be resolved by performing a manual uninstall as shown on the Solving Error 1721 page.

How can I remotly deploy NetModem Client with pre-configured COM ports?

This can be done by passing the installer a registry configuration file for the Virtual COM port settings on the command line. Please review the NetModem Unattended Installation tips for details.


What version of OpenSSL does NetModem use?

NetModem uses the latest version of the OpenSSL 1.0.2 branch. OpenSSL is an Encryption Library that allows a secure connection between the server and the client connections.. Over the years, security exploits and vulnerabilities have been discovered in OpenSSL from time to time, and when this happens the OpenSSL team releases an updated version to fix such issues. Due to the importance of such issues, we will generally release a new version of NetModem within a few days of a new version of OpenSSL being released.


Why doesn't encryption work?

Because encryption is not avalible in all countries the evaluation version may have the encryption feature disabled by default. Contact your account manager if you require encryption.

The sample SSL certificate included with NetModem server is not signed by a Certificate Authority, so when testing with this certificate the client should be configured to *not* require a signed certificate (found under advanced options in the client configuration). The sample certificate should only be used for testing purposes, as it uses a known password and is therefore not truly secure.

If you need assistance with encryption please go to the support section of our web site and a fill out a support request.

 

 

 

 



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