The Tunneling bar allows you to monitor open TCP/IP forwarding channels and add or remove forwarding rules instantly. It is meaningful only when the connection protocol is SSH. It has two tabs, Channels and Forwarding rules.Channels
The Channels tab contains currently open channels. You can force to terminate open channels by clicking the right button on the channels you want to close.
The ID column shows a sequence number of the open channels. The number is allocated uniquely for each session in the order of creation. The Type column shows the type of each channel. The supported types are session, X11, direct-tcpip, and forwarded-tcpip. A session channel is created when a terminal is allocated. An X11 channel is created when a remote X application connects to a local X server. A direct-tcpip and forwarded-tcpip channels are created when a connection that is defined in the forwarding rules is established. The From column shows the host and port from which the connection is originating. The To column shows the host and port to which the connection is established. The Created column shows the creation time of the channels.Forwarding Rules
This tab shows TCP/IP forwarding rules used on the current session. When an ssh connection is established, all the forwarding rules defined in the Tunneling page of Properties dialog box are created and listed here.
The Source column shows the host and port that is forwarded to a destination port. The Destination column shows the host and port to which a source port is forwarded. The Status column shows the status of a rule. The status has four states: Waiting, Open, Failed, and Suspended. Waiting is displayed when a rule is not ready to create channels yet. If everything works well, it will be changed to Open. Open is displayed when a rule is ready to accept channel requests. Failed is displayed when a rule is incorrect, the ssh server refuses the rule, or the port is already allocated by another program. Suspended is displayed when you click Suspend from the shortcut menu. You can resume the suspended rule by clicking the right button on the rule, and then clicking Resume.
Xshell allows you to add or remove forwarding rules instantly. To add a new rule or remove the existing one, just right-click on the list, and then choose a command on the menu.