As of Cisco IOS Release 12.4(11)T, peer public RSA key modulus values up to 4096 bits are automatically supported. The largest private RSA key modulus is 4096 bits. Therefore, the largest RSA private key a router may generate or import is 4096 bits. Cisco 3850 VTY (SSH) lines hung by Prime - bug Hi, It seems we have run into this bug with our deployment of the 3850 switches. Bug ID is: keyCSCuv84149key We are currently running IOS XE version 3.03.03 and have had 3 switch stacks with this bug in the last 2 weeks and we are now concerned that it will continue to happen.
router(config)# hostname R1
R1(config)# ip domain-name ccie.com
–> To define a default domain name that the Cisco IOS software uses to complete unqualified host names
R1(config)# ip domain-name ccie.com
–> To define a default domain name that the Cisco IOS software uses to complete unqualified host names
R1(config)# crypto key generate rsa
–> To generate RSA key pairs
–> To generate RSA key pairs
The name for the keys will be: R1.ccie.com
Choose the size of the key modulus in the range of 360 to 2048 for your General purpose keys. Watch dogs serial key generator password. Choosing a key modulus
greater than 512 may take a few minutes
Choose the size of the key modulus in the range of 360 to 2048 for your General purpose keys. Watch dogs serial key generator password. Choosing a key modulus
greater than 512 may take a few minutes
How many bits in the modulus [512]: 1024
–> modulus : determines the strength of the key , the higher the modulus number the strong the key is
the higher the modulus number the more CPU cycles you are going to have to use encrypt and decrypt
–> modulus : determines the strength of the key , the higher the modulus number the strong the key is
the higher the modulus number the more CPU cycles you are going to have to use encrypt and decrypt
Cisco 3850 Generate Rsa Key With Openssl
R1(config)# username edaoud privilege 15 secret cisco
–> To establish a username-based authentication system
–> To establish a username-based authentication system
R1(config)# line vty 0 4
–> for telnet per default, there is five lines, 0 to 4
–> for telnet per default, there is five lines, 0 to 4
R1(config-line)# login local
–> To enable password checking at login
–> To enable password checking at login
R1(config-line)# transport input ssh
–> To define protocol SSH to be used to connect to a specific line of the router
–> To define protocol SSH to be used to connect to a specific line of the router
R1(config)# ip ssh version 2
–> Specify protocol version to be supported
–> Specify protocol version to be supported
R1(config)# ip ssh time-out <0-120> ms
–> Specify SSH time-out interval
–> Specify SSH time-out interval
R1(config)# ip ssh authentication-retries <0-5>
–> Specify number of authentication retries
–> Specify number of authentication retries
R1(config)# ip ssh maxstartups
–> Max concurrent session allowed
–> Max concurrent session allowed
R2# ssh -l edaoud 10.1.12.1
–> Specifies the user ID to use when logging in on the remote networking device that is running the SSH server.
–> Specifies the user ID to use when logging in on the remote networking device that is running the SSH server.
router# show ssh
%No SSHv2 server connections running.
%No SSHv1 server connections running.
%No SSHv2 server connections running.
%No SSHv1 server connections running.
router# sh ip ssh
SSH Disabled – version 1.99
%Please create RSA keys to enable SSH (and of atleast 768 bits for SSH v2).
Authentication timeout: 120 secs; Authentication retries: 3
Minimum expected Diffie Hellman key size : 1024 bits
IOS Keys in SECSH format(ssh-rsa, base64 encoded): NONE
SSH Disabled – version 1.99
%Please create RSA keys to enable SSH (and of atleast 768 bits for SSH v2).
Authentication timeout: 120 secs; Authentication retries: 3
Minimum expected Diffie Hellman key size : 1024 bits
IOS Keys in SECSH format(ssh-rsa, base64 encoded): NONE
router# show control-plan host open-ports
router# show tcp
router# show tcp
Below Quote are taken from CCIE Routing and Switching Exam Certification Guide 4th Edition.
Using Secure Shell Protocol
Telnethas long been used to manage network devices; however, Telnet traffic is sent in clear text. Anyone
able to sniff that traffic would see your password and any other information sent during the Telnet
session. Secure Shell (SSH) is a much more secure way to manage your routers and switches. It
is a client/server protocol that encrypts the traffic in and out through the vty ports.
Cisco routers and switches can act as SSH clients by default, but must be configured to be SSH
servers. That is, they can use SSH when connecting to another device, but require configuration
before allowing devices to connect via SSH to them. They also require some method of
authenticating the client. This can be either a local username and password, or authentication with
a AAA server (AAA is detailed in the next section).
There are two versions of SSH. SSH Version 2 is an IETF standard that is more secure than version
1. Version 1 is more vulnerable to man-in-the-middle attacks, for instance. Cisco devices support
both types of connections, but you can specify which version to use.
Telnet is enabled by default, but configuring even a basic SSH server requires several steps:
1. Ensure that your IOS supports SSH. You need a K9 image for this.
2. Configure a host name, unless this was done previously.
3. Configure a domain name, unless this was done previously.
4. Configure a client authentication method.
5. Tell the router or switch to generate the Rivest, Shamir, and Adelman (RSA) keys that will be
used to encrypt the session.
6. Specify the SSH version, if you want to use version 2.
7. Disable Telnet on the VTY lines.
8. Enable SSH on the VTY lines.
Example 18-4 shows a router being configured to act as an SSH server.
able to sniff that traffic would see your password and any other information sent during the Telnet
session. Secure Shell (SSH) is a much more secure way to manage your routers and switches. It
is a client/server protocol that encrypts the traffic in and out through the vty ports.
Cisco routers and switches can act as SSH clients by default, but must be configured to be SSH
servers. That is, they can use SSH when connecting to another device, but require configuration
before allowing devices to connect via SSH to them. They also require some method of
authenticating the client. This can be either a local username and password, or authentication with
a AAA server (AAA is detailed in the next section).
There are two versions of SSH. SSH Version 2 is an IETF standard that is more secure than version
1. Version 1 is more vulnerable to man-in-the-middle attacks, for instance. Cisco devices support
both types of connections, but you can specify which version to use.
Telnet is enabled by default, but configuring even a basic SSH server requires several steps:
1. Ensure that your IOS supports SSH. You need a K9 image for this.
2. Configure a host name, unless this was done previously.
3. Configure a domain name, unless this was done previously.
4. Configure a client authentication method.
5. Tell the router or switch to generate the Rivest, Shamir, and Adelman (RSA) keys that will be
used to encrypt the session.
6. Specify the SSH version, if you want to use version 2.
7. Disable Telnet on the VTY lines.
8. Enable SSH on the VTY lines.
Example 18-4 shows a router being configured to act as an SSH server.
Example 18-4 SSH Configuration
router(config)# hostname R3
R3(config)# ip domain-name CCIE2B
R3(config)# username cisco password Cisco
R3(config)# crypto key generate rsa
The name for the keys will be: R3.CCIE2B
Choose the size of the key modulus in the range of 360 to 2048 for your
General Purpose Keys. Choosing a key modulus greater than 512 may take
a few minutes.
How many bits in the modulus [512]: 1024
% Generating 1024 bit RSA keys …[OK]
R3(config)#
*May 22 02:06:51.923: %SSH-5-ENABLED: SSH 1.99 has been enabled
R3(config)# ip ssh version 2
!
R3(config)# line vty 0 4
R3(config-line)# transport input none
R3(config-line)# transport input ssh
R3(config-line)#^Z
!
R3# show ip ssh
SSH Enabled- version 2.0
Authentication timeout: 120 secs; Authentication retries: 3
router(config)# hostname R3
R3(config)# ip domain-name CCIE2B
R3(config)# username cisco password Cisco
R3(config)# crypto key generate rsa
The name for the keys will be: R3.CCIE2B
Choose the size of the key modulus in the range of 360 to 2048 for your
General Purpose Keys. Choosing a key modulus greater than 512 may take
a few minutes.
How many bits in the modulus [512]: 1024
% Generating 1024 bit RSA keys …[OK]
R3(config)#
*May 22 02:06:51.923: %SSH-5-ENABLED: SSH 1.99 has been enabled
R3(config)# ip ssh version 2
!
R3(config)# line vty 0 4
R3(config-line)# transport input none
R3(config-line)# transport input ssh
R3(config-line)#^Z
!
R3# show ip ssh
SSH Enabled- version 2.0
Authentication timeout: 120 secs; Authentication retries: 3
Contents
Finding Feature Information
Your software release may not support all the features documented in this module. For the latest feature information and caveats, see the release notes for your platform and software release.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.
Prerequisites for Configuring the Switch for Secure Shell (SSH) and Secure Copy Protocol (SCP)
The following are the prerequisites for configuring the switch for secure shell (SSH):
- For SSH to work, the switch needs an RSA public/private key pair. This is the same with Secure Copy Protocol (SCP), which relies on SSH for its secure transport.
- Before enabling SCP, you must correctly configure SSH, authentication, and authorization on the switch.
- Because SCP relies on SSH for its secure transport, the router must have an Rivest, Shamir, and Adelman (RSA) key pair.
- SCP relies on SSH for security.
- SCP requires that authentication, authorization, and accounting (AAA) authorization be configured so the router can determine whether the user has the correct privilege level.
- A user must have appropriate authorization to use SCP.
- A user who has appropriate authorization can use SCP to copy any file in the Cisco IOS File System (IFS) to and from a switch by using the copy command. An authorized administrator can also do this from a workstation.
Related Concepts
Restrictions for Configuring the Switch for SSH
The following are restrictions for configuring the switch for secure shell.
- The switch supports Rivest, Shamir, and Adelman (RSA) authentication.
- SSH supports only the execution-shell application.
- The SSH server and the SSH client are supported only on DES (56-bit) and 3DES (168-bit) data encryption software.
- The switch supports the Advanced Encryption Standard (AES) encryption algorithm with a 128-bit key, 192-bit key, or 256-bit key. However, symmetric cipher AES to encrypt the keys is not supported.
- This software release does not support IP Security (IPSec).
- When using SCP, you cannot enter the password into the copy command. You must enter the password when prompted.
Related Concepts
Information about SSH
Secure Shell (SSH) is a protocol that provides a secure, remote connection to a device. SSH provides more security for remote connections than Telnet does by providing strong encryption when a device is authenticated. This software release supports SSH Version 1 (SSHv1) and SSH Version 2 (SSHv2).
SSH and Switch Access
For SSH configuration examples, see the “SSH Configuration Examples” section in the “Configuring Secure Shell” section in the “Other Security Features” chapter of the Cisco IOS Security Configuration Guide, Cisco IOS Release 12.4.
SSH functions the same in IPv6 as in IPv4. For IPv6, SSH supports IPv6 addresses and enables secure, encrypted connections with remote IPv6 nodes over an IPv6 transport.
Note | Generate ssh key github. For complete syntax and usage information for the commands used in this section, see the command reference for this release and the “Secure Shell Commands” section of the “Other Security Features” chapter of the Cisco IOS Security Command Reference, Release 12.4 and the Cisco IOS IPv6 Command Reference. |
SSH Servers, Integrated Clients, and Supported Versions
The SSH feature has an SSH server and an SSH integrated client, which are applications that run on the switch. You can use an SSH client to connect to a switch running the SSH server. The SSH server works with the SSH client supported in this release and with non-Cisco SSH clients. The SSH client also works with the SSH server supported in this release and with non-Cisco SSH servers.
The switch supports an SSHv1 or an SSHv2 server.
The switch supports an SSHv1 client.
SSH supports the Data Encryption Standard (DES) encryption algorithm, the Triple DES (3DES) encryption algorithm, and password-based user authentication.
SSH also supports these user authentication methods:
- TACACS+
- RADIUS
- Local authentication and authorization
Related Concepts
Related Tasks
SSH Configuration Guidelines
Follow these guidelines when configuring the switch as an SSH server or SSH client:
- An RSA key pair generated by a SSHv1 server can be used by an SSHv2 server, and the reverse.
- If the SSH server is running on a stack master and the stack master fails, the new stack master uses the RSA key pair generated by the previous stack master.
- If you get CLI error messages after entering the crypto key generate rsa global configuration command, an RSA key pair has not been generated. Reconfigure the hostname and domain, and then enter the crypto key generate rsa command. For more information, see Related Topics below.
- When generating the RSA key pair, the message No host name specified might appear. If it does, you must configure a hostname by using the hostname global configuration command.
- When generating the RSA key pair, the message No domain specified might appear. If it does, you must configure an IP domain name by using the ip domain-name global configuration command.
- When configuring the local authentication and authorization authentication method, make sure that AAA is disabled on the console.
Related Tasks
Secure Copy Protocol Overview
The Secure Copy Protocol (SCP) feature provides a secure and authenticated method for copying switch configurations or switch image files. SCP relies on Secure Shell (SSH), an application and a protocol that provides a secure replacement for the Berkeley r-tools.
For SSH to work, the switch needs an RSA public/private key pair. This is the same with SCP, which relies on SSH for its secure transport.
Because SSH also relies on AAA authentication, and SCP relies further on AAA authorization, correct configuration is necessary.
- Before enabling SCP, you must correctly configure SSH, authentication, and authorization on the switch.
- Because SCP relies on SSH for its secure transport, the router must have an Rivest, Shamir, and Adelman (RSA) key pair.
Note | When using SCP, you cannot enter the password into the copy command. You must enter the password when prompted. |
Secure Copy Protocol Concepts
The Secure Copy Protocol (SCP) feature provides a secure and authenticated method for copying switch configurations or switch image files. SCP relies on Secure Shell (SSH), an application and a protocol that provides a secure replacement for the Berkeley r-tools.
To configure the Secure Copy feature, you should understand the SCP concepts.
The behavior of SCP is similar to that of remote copy (rcp), which comes from the Berkeley r-tools suite, except that SCP relies on SSH for security. SCP also requires that authentication, authorization, and accounting (AAA) authorization be configured so the router can determine whether the user has the correct privilege level.
For information about how to configure and verify SCP, see the “Secure Copy Protocol” section in the Cisco IOS Security Configuration Guide: Securing User Services, Release 12.4.
Related References
How to Configure SSH
Setting Up the Switch to Run SSH
Beginning in privileged EXEC mode, follow these steps to set up your switch to run SSH: Nba 2k18 mac download free.
Before You BeginConfigure user authentication for local or remote access. This step is required. For more information, see Related Topics below.
SUMMARY STEPS2.hostnamehostname
3.ip domain-namedomain_name
4.crypto key generate rsa
5.end
DETAILED STEPS
Command or Action | Purpose | |||
---|---|---|---|---|
Step 1 | configureterminal Example: | Enters the global configuration mode. | ||
Step 2 | hostnamehostname Example: | Configures a hostname and IP domain name for your switch.
| ||
Step 3 | ip domain-namedomain_name Example: | Configures a host domain for your switch. | ||
Step 4 | crypto key generate rsa Example: | Enables the SSH server for local and remote authentication on the switch and generates an RSA key pair. Generating an RSA key pair for the switch automatically enables SSH. We recommend that a minimum modulus size of 1024 bits. When you generate RSA keys, you are prompted to enter a modulus length. A longer modulus length might be more secure, but it takes longer to generate and to use.
| ||
Step 5 | end Example: | Returns to privileged EXEC mode. |
Related Concepts
Cisco 3850 Generate Rsa Key Pair
Related Tasks
Generate Rsa Key Command
Configuring the SSH Server
Beginning in privileged EXEC mode, follow these steps to configure the SSH server:
Note | This procedure is only required if you are configuring the switch as an SSH server. |
- transport input ssh
1.configureterminal
2.ip sshversion [1 | 2]
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https://celestialtasty.weebly.com/gihosoft-mobile-transfer-software-for-mac.html.
3.ip ssh {timeoutseconds | authentication-retriesnumber}
4.Use one or both of the following:
5.end
DETAILED STEPS
Command or Action | Purpose | |
---|---|---|
Step 1 | configureterminal Example: | Enters the global configuration mode. |
Step 2 | ip sshversion [1 | 2] Example: | (Optional) Configures the switch to run SSH Version 1 or SSH Version 2.
If you do not enter this command or do not specify a keyword, the SSH server selects the latest SSH version supported by the SSH client. For example, if the SSH client supports SSHv1 and SSHv2, the SSH server selects SSHv2. |
Step 3 | ip ssh {timeoutseconds | authentication-retriesnumber} Example: | Configures the SSH control parameters:
Repeat this step when configuring both parameters. |
Step 4 | Use one or both of the following:
Example: or | (Optional) Configures the virtual terminal line settings.
|
Step 5 | end Example: | Returns to privileged EXEC mode. |
Monitoring the SSH Configuration and Status
Command | Purpose |
---|---|
show ip ssh | Shows the version and configuration information for the SSH server. C generate bitcoin private key. Kaspersky 2013 internet security key generator. |
show ssh | Shows the status of the SSH server. |
For more information about these commands, see the “Secure Shell Commands” section in the “Other Security Features” chapter of the Cisco IOS Security Command Reference .
Additional References
Related Documents
Related Topic | Document Title |
---|---|
Configuring Identity Control policies and Identity Service templates for Session Aware networking. | Session Aware Networking Configuration Guide, Cisco IOS XE Release 3SE (Catalyst 3850 Switches) |
Configuring RADIUS, TACACS+, Secure Shell, 802.1X and AAA. | Securing User Services Configuration Guide Library, Cisco IOS XE Release 3SE (Catalyst 3850 Switches) |
Error Message Decoder
Description | Link |
---|---|
To help you research and resolve system error messages in this release, use the Error Message Decoder tool. |
MIBs
MIB | MIBs Link |
---|---|
All supported MIBs for this release. | To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL: |
Technical Assistance
Description | Link |
---|---|
The Cisco Support website provides extensive online resources, including documentation and tools for troubleshooting and resolving technical issues with Cisco products and technologies. To receive security and technical information about your products, you can subscribe to various services, such as the Product Alert Tool (accessed from Field Notices), the Cisco Technical Services Newsletter, and Really Simple Syndication (RSS) Feeds. Access to most tools on the Cisco Support website requires a Cisco.com user ID and password. |