VNC^® Enterprise Edition User Guide

Preventing particular connections to VNC Server

You can prevent particular users connecting to VNC Server. To do this, you can either:

•  Prevent connections from particular client computers. See below for more information.

•  Prevent particular users connecting. See Preventing particular users connecting for more information.

Note: You can prevent all users connecting to VNC Server. For more information, see Preventing connections to VNC Server.

Preventing connections from particular client computers

You can prevent all connections originating from one or more particular client computers by filtering the network addresses of those client computers.

Note: If you filter network addresses, IPv6 network addresses for the host computer become unavailable. A user cannot enter an IPv6 network address in order to connect to VNC Server (even from an authorized client computer).

To filter network addresses, open the VNC Server Properties dialog. For more information on this dialog, see Using the VNC Server Properties dialog. On the Connections tab, click the IP Filter button. The Configure IP Address Filtering dialog opens:

(Windows XP)

By default, connection requests are accepted from all client computers. To reject connection requests from a particular client computer, click the Add button. The Configure IP Address or Subnet dialog opens:

(Windows XP)

Enter the network address, or a range of addresses, in IPv4 format, and choose one of the following options:

Note that if you filter network addresses, the order of rules in the Configure IP Address Filtering dialog is important. The first matching rule determines what happens to connection requests from a particular client computer. For example, if a rule rejecting a client computer is encountered before one accepting it, then all connection requests from that client computer will always be rejected. You can move rules in the dialog using the Up and Down arrows.

By default, the Default rule accepts connection requests from all client computers. You can change this so that it rejects or queries all connection requests instead. To do this, select the Default rule, and click the Edit button. You cannot move this rule in the dialog.

Preventing particular users connecting

You can prevent a particular user connecting by causing a connection prompt to appear on the host computer’s desktop:

(Windows XP)

A connection prompt enables a host computer user, if one is present, to either accept the connection request, allow ‘view only’ access to the host computer, or reject the request. If no host computer user is present, or if no response is received within ten seconds, then the connection request is automatically rejected. Note if you are setting up VNC Server on your own computer for remote access then enabling this feature may prevent you connecting.

Note that a user supplying credentials granting a Full set of VNC permissions is able to bypass connection prompts. A host computer user cannot prevent these users connecting by default. You can configure the Connect without accept/reject prompt permission to either permit other users to bypass connection prompts, or to submit all users, including users with Full VNC permissions, to them. For more information, see Customizing VNC permissions.

To cause connection prompts to appear, open the VNC Server Properties dialog. For more information on this dialog, see Using the VNC Server Properties dialog. On the Connections tab, turn on Prompt VNC Server user to approve connections:

(Windows XP)

Clearly, this feature is only useful if a host computer user is present.

Note: Under UNIX or Linux, for VNC Server in Virtual Mode, no host computer user is ‘present’. This feature is therefore only useful if at least one user is able to bypass connection prompts. Such a user can then accept or reject subsequent connection requests.

For VNC Server in Service Mode, if a host computer user is only likely to be intermittently present, you should also turn on Only prompt when there is a user logged on. This means connection prompts will only appear if a host computer user is logged on (and therefore likely to be present). If no host computer user is logged on, connection prompts will not appear. In these circumstances, all users are able to connect, though note they must then log on to the host computer in order to continue.