transport input all
Configures a VTY line to accept all supported protocols (Telnet, SSH, etc.) for incoming connections, typically used to allow remote management access.
transport input allWhen to Use This Command
- Enabling both Telnet and SSH on VTY lines for network devices that need to support legacy and secure access methods.
- Configuring a lab router to accept any transport protocol for testing and troubleshooting remote connectivity.
- Allowing multiple management protocols during a migration from Telnet to SSH without disrupting existing access.
- Setting up a device in a multi-vendor environment where different administrators use different protocols.
Command Examples
Enable all transport protocols on VTY lines 0-4
line vty 0 4
transport input allRouter(config-line)# transport input all Router(config-line)#
The command is entered in line configuration mode. No output is shown upon success; the prompt returns. This enables Telnet, SSH, and other supported protocols on VTY lines 0 through 4.
Verify transport input configuration
show running-config | include line vty|transport inputline vty 0 4 transport input all
The 'show running-config' output confirms that the VTY lines are configured with 'transport input all'. The first line indicates the VTY lines being configured, and the second line shows the transport setting.
Understanding the Output
The 'transport input all' command does not produce any output upon execution; it silently configures the line. To verify, use 'show running-config' or 'show line'. In 'show running-config', look for 'transport input all' under the relevant 'line vty' section. If you see 'transport input none' or 'transport input telnet', that indicates restricted protocols. A common mistake is to forget that 'transport input all' includes Telnet, which is insecure; for production, use 'transport input ssh' instead.
CCNA Exam Tips
CCNA exam tip: 'transport input all' enables both Telnet and SSH; for security, the exam expects 'transport input ssh' only.
CCNA exam tip: Remember that 'transport input' is configured under 'line vty' mode, not globally.
CCNA exam tip: If a VTY line has 'transport input none', no remote access is possible; this is a common misconfiguration.
CCNA exam tip: The exam may ask which protocol is allowed when 'transport input all' is set; answer: Telnet, SSH, and others.
Common Mistakes
Mistake 1: Using 'transport input all' in production, exposing the device to insecure Telnet access.
Mistake 2: Forgetting to apply the command to all VTY lines (e.g., only configuring line vty 0 but not 1-4).
Mistake 3: Confusing 'transport input' with 'transport output'; input controls incoming connections, output controls outgoing.
Related Commands
line vty 0 4
Enters line configuration mode for virtual terminal (VTY) lines 0 through 4 to configure remote access settings like Telnet/SSH, ACLs, and timeout parameters.
show line
Displays line configuration and status information for console, auxiliary, and vty lines, used to verify line settings and monitor user connections.
transport input ssh
Restricts incoming Telnet or SSH connections on a VTY line to only SSH, blocking unencrypted Telnet access for secure remote management.
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