Command:

transport input

Mode:

Router(config-line)#

Syntax:

transport input {all | lat | mop | nasi | none | pad | rlogin | ssh | telnet | v120}

no transport input

Syntax Description:

all	Selects all protocols.
lat	Selects the Digital LAT protocol and specifies both incoming reverse LAT and host-initiated connections.
mop	Selects Maintenance Operation Protocol (MOP).
nasi	Select NetWare Access Servers Interface (NASI) as the input transport protocol.
none	Prevents any protocol selection on the line. This makes the port unusable by incoming connections.
pad	Selects X.3 PAD incoming connections.
rlogin	Selects the UNIX rlogin protocol.
ssh	Selects the Secure Shell (SSH) protocol.
telnet	Specifies all types of incoming TCP/IP connections.
v120	Select the V.120 protocol for incoming async over ISDN connections.

 

Command Description:

To define which protocols to use to connect to a specific line of the router, use the transport input line configuration command.

One protocol, multiple protocols, all protocols, or no protocols can be specified. To specify multiple protocols, enter the keyword for each protocol, separated by a space.

This command can be useful in distributing resources among different types of users, or making certain that only specific hosts can access a particular port. When using two-step protocol translation, the transport input command is useful in controlling exactly which protocols can be translated to other protocols.

Access lists for each individual protocol can be defined in addition to the allowances created by the transport input command. Any settings made with the transport input command override settings made with the transport preferred command.

Usage Guidelines:

Cisco routers do not accept incoming network connections to asynchronous ports (TTY lines) by default. An incoming transport protocol has to be specified, or specify transport input all before the line will accept incoming connections. For example, if you are using your router as a terminal server to make console-port connections to routers or other devices, you will not be able to use Telnet to connect to these devices. You will receive the message "Connection Refused." This behavior is new as of Cisco IOS Software Release 11.1. Previous to release 11.1, the default was transport input all. If upgrading to Cisco IOS software version 11.1(1) or later from Cisco IOS software Release 11.0 or earlier, the transport input {protocol | all} command must be added, otherwise the Telnet session will not function and router access will be denied.

Example:

The following example sets the incoming protocol to Telnet for vtys 0 to 4:

 

Router(config)#line vty 0 4

Router(config-line)#transport input telnet

Misconceptions:

Related commands: