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Why should you configure the vty lines for the switch?
If you do not configure a vty pass you will not be able to telnet to the switch
Which two interfaces will allow access via the VTY lines to configure the router?
USb or AUX
When implementing a dynamic ACL Why is necessary to include an extended ACL as part of the configuration process?
.to disable the router vty lines
What is the full form of VTY?
VTY means -- virtual TTY (teletype)
Which two configurations must be completed before an RSA key can be generated on a router?
a domain name local authentication on the VTY lines
Which two configuration must be completed before an RSA key can be generated on a router?
a domain name local authentication on the VTY lines
Which command will configure all the default VTY ports on a router?
Router(config)# line vty 0 4
What does the command line vty 0 1 mean?
vty stands for virtual terminal; it is used for connections such as Telnet or the safer SSH. The numbers 0 1 refer to a range of possible connections. Usually all possible connections on a router or switch should be programmed together, since you don't have control over which user accesses which connection.
What does command line vty 0 1 mean?
vty stands for virtual terminal; it is used for connections such as Telnet or the safer SSH. The numbers 0 1 refer to a range of possible connections. Usually all possible connections on a router or switch should be programmed together, since you don't have control over which user accesses which connection.
What is the function of line vty in router configuration?
Vty Line Authentication and AuthorizationThe system supports 20 virtual tty (vty) lines for Telnet, Secure Shell Server (SSH) and FTP services. Each Telnet, SSH, or FTP session requires one vty line. You can add security to your system by configuring the software to validate login requests. There are two modes of authentication for a vty line:Simple authentication - password-only authentication via the local configurationAAA authentication - username and password authentication via a set of authentication serversYou can enable AAA authorization, which allows you to limit the services available to a user. Based on information retrieved from a user's profile, the user is either granted or denied access to the requested server.Configuring Simple AuthenticationTo configure simple authentication: Specify a vty line or a range of vty lines on which you want to enable the password.host1(config)#line vty 8 13 host1(config-line)# Specify the password for the vty lines.host1(config-line)#password 0 mypassword Enable login authentication on the lines.host1(config-line)#login Display your vty line configuration.host1#show line vty 8 no access-class in data-character-bits 8 exec-timeout never exec-banner enabled motd-banner enabled login-timeout 30 seconds lineUse to specify the vty line(s) on which you want to enable the password.You can set a single line or a range of lines. The range is 0-19.Examplehost1(config)#line vty 8 13 Use the no version to remove a vty line or a range of lines from your configuration; users will not be able to run Telnet, SSH, or FTP to lines that you remove. When you remove a vty line, the system removes all lines above that line. For example, no line vty 6 causes the system to remove lines 6 through 19. You cannot remove lines 0 through 4.loginUse to enable password checking at login.The default setting is to enable a password.Examplehost1(config-line)#login Use the no version to disable password checking and allow access without a password.passwordUse to specify a password on a single line or a range of lines.If you enable password checking but do not configure a password, the system will not allow you to access virtual terminals.Specify a password in plain text (unencrypted) or cipher text (encrypted). In either case, the system stores the password as encrypted.Use the following keywords to specify the type of password you will enter:0 (zero) - unencrypted password5 - secret7 - encrypted passwordNote: To use an encrypted password or a secret, you must follow the procedure in Setting Basic Password Parameters earlier in this chapter to obtain the encrypted password or secret. You cannot create your own encrypted password or secret; you must use a system-generated password or secret.Example 1 (unencrypted password)host1(config-line)#password 0 mypassword Example 2 (secret)host1(config-line)#password 5 bcA";+1aeJD8)/[1ZDP6Example 3 (encrypted password)host1(config-line)#password 7 dq]XG`,%N"SS7d}o)_?YUse the no version to remove the password. By default, no password is specified.show line vtyUse to display the configuration of a vty line.Field descriptionsaccess-class - access-class associated with the vty linedata-character-bits - number of bits per character7 - setting for the standard ASCII set8 - setting for the international character setexec-timeout - time interval that the terminal waits for expected user inputNever - indicates that there is no time limitexec-banner - status for the exec banner: enabled or disabled. This banner is displayed by the CLI after user authentication (if any) and before the first prompt of a CLI session.motd-banner - status for the MOTD banner: enabled or disabled. This banner is displayed by the CLI when a connection is initiated.login-timeout - time interval during which the user must log in.Never - indicates that there is no time limitExamplehost1#show line vty 0 no access-class in data-character-bits 8 exec-timeout 3w 3d 7h 20m 0s exec-banner enabled motd-banner enabled login-timeout 30 seconds Configuring AAA Authentication and AAA AuthorizationBefore you configure AAA authentication and AAA authorization, you need to configure a RADIUS and/or TACACS+ authentication server. Note that several of the steps in the configuration procedure are optional. To configure AAA new model authentication and authorization for inbound sessions to vty lines on your system:Specify AAA new model authentication.host1(config)#aaa new-modelCreate an authentication list that specifies the type(s) of authentication methods allowed.host1(config)#aaa authentication login my_auth_list tacacs+ line enable(Optional) Specify the privilege level by defining a method list for authentication.host1(config)aaa authentication enable default tacacs+ radius enable(Optional) Enable authorization, and create an authorization method list.host1(config)aaa authorization commands 15 Boston if-authenticated tacacs+(Optional) Disable authorization for all Global Configuration commands.host1(config)#no aaa authorization config-commandsSpecify the range of vty lines.host1(config)#line vty 6 10 host1(config-line)# (Optional) Apply an authorization list to a vty line or a range of vty lines.host1(config-line)#authorization commands 15 BostonSpecify the password for the vty lines.host1(config-line)#password xyz Apply the authentication list to the vty lines you specified on your system.host1(config-line)#login authentication my_auth_listaaa authentication enable defaultUse to allow privilege determination to be authenticated through the TACACS+ or RADIUS server. This command specifies a list of authentication methods that are used to determine whether a user is granted access to the privilege command level.The authentication methods that you can use in a list include these options: radius, line, tacacs+, none, and enable.To specify that the authentication should succeed even if all methods return an error, specify none as the final method in the command line.Requests sent to a TACACS+ or RADIUS server include the username that is entered for login authentication.If the authentication method list is empty, the local enable password is used.Examplehost1(config)#aaa authentication enable default tacacs+ radiusUse the no version to empty the list.aaa authentication loginUse to set AAA authentication at login. This command creates a list that specifies the methods of authentication.Once you specify aaa new-model as the authentication method for vty lines, an authentication list called "default" is automatically assigned to the vty lines. To allow users to access the vty lines, you must create an authentication list and either:Name the list "default."Assign a different name to the authentication list, and assign the new list to the vty line using the login authenticationcommand.The authentication methods that you can use in a list include these options: radius, line, tacacs+, none, and enable.The system traverses the list of authentication methods to determine whether a user is allowed to start a Telnet session. If a specific method is available but the user information is not valid (such as an incorrect password), the system does not continue to traverse the list and denies the user a session.If a specific method is unavailable, the system continues to traverse the list. For example, if tacacs+ is the first authentication type element on the list and the TACACS+ server is unreachable, the system attempts to authenticate with the next authentication type on the list, such as radius.The system assumes an implicit denial of service if it reaches the end of the authentication list without finding an available method.Examplehost1(config)#aaa authentication login my_auth_list tacacs+ radius line noneUse the no version to remove the authentication list from your configuration.aaa authorizationUse to set the parameters that restrict access to a network.Use the keyword exec to determine if the user is allowed to run User Exec mode commands. The commands you can execute from User Exec mode provide only user-level access.Use the keyword commands to run authorization for all commands at the specified privilege level (0- 15). See Table 6-1 for a description of privilege levels.You can enter up to three authorization types to use in an authorization method list. Options include: if-authenticated, none, and tacacs+.Note: For information about TACACS+, see the ERX Broadband Access Configuration Guide, Chapter 4, Configuring TACACS+.Authorization method lists define the way authorization is performed and the sequence in which the methods are performed. You can designate one or more security protocols in the method list to be used for authorization. If the initial method fails, the next method in the list is used. The process continues until either there is successful communication with a listed authorization method or all methods defined are exhausted.Examplehost1(config)#aaa authorization execUse the no version to delete method list.aaa authorization config-commandsUse to reestablish the default created when the aaa authorization commands command was issued.After the aaa authorization commands command has been issued, aaa authorization config-commands is enabled by default, which means that all configuration commands in Exec mode are authorized.Examplehost1(config)#aaa new-model host1(config)#aaa authorization command 15 parks tacacs+ none host1(config)#no aaa authorization config-commandsUse the no version to disable AAA configuration command authorization.aaa new-modelUse to specify AAA new model as the authentication method for the vty lines on your system.If you specify AAA new model and you do not create an authentication list, users will not be able to access the system through a vty line.Examplehost1(config)#aaa new-modelUse the no version to restore simple authentication.authorizationUse to apply AAA authorization to a specific vty line or group of lines.Use the exec keyword to apply this authorization to CLI access in general.Use the commands keyword to apply this authorization to user commands of the privilege level you specify.You can specify the name of an authorization method list; if no method list is specified, the default is used.After you enable the aaa authorization command and define a named authorization method list (or use the default method list) for a particular type of authorization, you must apply the defined list to the appropriate lines for authorization to take place.Examplehost1(config)#line vty 6 host1(line-config)#authorization commands 15 sonnyUse the no version to disable authorization.lineUse to specify the virtual terminal lines.You can set a single line or a range of lines. The range is 0-19.Examplehost1(config)#line vty 6 10 Use the no version to remove a vty line or a range of lines from your configuration; users will not be able to run Telnet, SSH, or FTP to lines that you remove. When you remove a vty line, the system removes all lines above that line. For example, no line vty 6 causes the system to remove lines 6 through 19. You cannot remove lines 0 through 4.login authenticationUse to apply an authentication list to the vty lines you specified on your system.Examplehost1(config-line)#login authentication my_auth_listUse the no version to specify that the system should use the default authentication list.passwordUse to specify a password on a line or a range of lines if you specified the line option with the aaa authentication login command.If you enable password checking but do not configure a password, the system will not allow you to access virtual terminals.Use the following keywords to specify the type of password you will enter:0 (zero) - unencrypted password5 - secret7 - encrypted password
Which password would allow a user to establish a Telnet session with a Cisco device?
On user exec mode type enable.When you are on the privilege mode type configure terminal.Upon reaching global config mode you have to type line vty 0 4.Inside the vty line mode type password Please see below example:Router>enableRouter#configure terminalEnter configuration commands, one per line. End with CNTL/Z.Router(config)#line vty 0 4Router(config-line)#password secretRouter(config-line)#exitRouter(config)#exit
What happens when the transport input ssh command is entered on the switch vty lines?
It will require you to SSH to the router rather than telnet. You will have to use a program like Putty or some other SSH client.
