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System Security Command Reference Guide for Cisco NCS 6000 Routers
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Preface
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Authentication, Authorization, and Accounting Commands
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IPSec Commands
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Keychain Management Commands
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Lawful Intercept\n\t Commands
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Management Plane Protection Commands
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Public Key Infrastructure Commands
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Software Authentication Manager Commands
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Secure Shell Commands
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Secure Socket Layer Protocol Commands
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Index
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Feedback
Contents
Secure Shell Commands
- clear ssh
- sftp
- sftp (Interactive Mode)
- show ssh
- show ssh session details
- ssh
- ssh client knownhost
- ssh client source-interface
- ssh client vrf
- ssh server
- ssh server logging
- ssh server rate-limit
- ssh server session-limit
- ssh server v2
- ssh timeout
clear ssh
Syntax Description
session-id
Session ID number of an incoming connection as displayed in the show ssh command output. Range is from 0 to 1024.
outgoing session-id
Specifies the session ID number of an outgoing connection as displayed in the show ssh command output. Range is from 1 to 10.
Command History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.
Use the clear ssh command to disconnect incoming or outgoing SSH connections. Incoming connections are managed by the SSH server running on the local networking device. Outgoing connections are initiated from the local networking device.
To display the session ID for a connection, use the show ssh command.
Task ID
In the following example, the show ssh command is used to display all incoming and outgoing connections to the router. The clear ssh command is then used to terminate the incoming session with the ID number 0.
RP/0/RP0/CPU0:router# show ssh SSH version: Cisco-2.0 session pty location state userid host ver -------------------------------------------------------------------- Incoming sessions 0 vty0 0/33/1 SESSION_OPEN cisco 172.19.72.182 v2 1 vty1 0/33/1 SESSION_OPEN cisco 172.18.0.5 v2 2 vty2 0/33/1 SESSION_OPEN cisco 172.20.10.3 v1 3 vty3 0/33/1 SESSION_OPEN cisco 3333::50 v2 Outgoing sessions 1 0/33/1 SESSION_OPEN cisco 172.19.72.182 v2 2 0/33/1 SESSION_OPEN cisco 3333::50 v2 RP/0/RP0/CPU0:router# clear ssh 0sftp
sftp [ username @ host : remote-filenam e ] source-filename dest-filename [ source-interface type interface-path-id ] [ vrf vrf-name ]
Syntax Description
username
(Optional) Name of the user performing the file transfer. The at symbol (@) following the username is required.
hostname:remote-filename
(Optional) Name of the Secure Shell File Transfer Protocol (SFTP) server. The colon (:) following the hostname is required.
source-filename
SFTP source, including the path.
dest-filename
SFTP destination, including the path.
source-interface
(Optional) Specifies the source IP address of a selected interface for all outgoing SSH connections.
type
Interface type. For more information, use the question mark (?) online help function.
interface-path-id
Physical interface or virtual interface.
Note Use the show interfaces command in EXEC mode to see a list of all interfaces currently configured on the router.
For more information about the syntax for the router, use the question mark (?) online help function.
vrf vrf-name
Specifies the name of the VRF associated with the source interface.
Command Default
If no username argument is provided, the login name on the router is used. If no hostname argument is provided, the file is considered local.
Command History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.
SFTP provides for the secure (and authenticated) copying of files between a router and a remote host. Like the copy command, the sftp command can be invoked only in EXEC mode.
If a username is not provided, the login name on the router is used as the default. If a host name is not provided, the file is considered local.
If the source interface is specified in the sftp command, the sftp interface takes precedence over the interface specified in the ssh client source-interface command.
When the file destination is a local path, all of the source files should be on remote hosts, and vice versa.
When multiple source files exist, the destination should be a preexisting directory. Otherwise, the destination can be either a directory name or destination filename. The file source cannot be a directory name.
If you download files from different remote hosts, that is, the source points to different remote hosts, the SFTP client spawns SSH instances for each host, which may result in multiple prompts for user authentication.
Task ID
In the following example, user abc is downloading the file ssh.diff from the SFTP server ena-view1 to disk0:
RP/0/RP0/CPU0:router#sftp abc@ena-view1:ssh.diff disk0In the following example, user abc is uploading multiple files from disk 0:/sam_* to /users/abc/ on a remote SFTP server called ena-view1:
RP/0/RP0/CPU0:router# sftp disk0:/sam_* abc@ena-view1:/users/abc/In the following example, user admin is downloading the file run from disk0a: to disk0:/v6copy on a local SFTP server using an IPv6 address:
RP/0/RP0/CPU0:router#sftp admin@[2:2:2::2]:disk0a:/run disk0:/V6copy Connecting to 2:2:2::2... Password: disk0a:/run Transferred 308413 Bytes 308413 bytes copied in 0 sec (338172)bytes/sec RP/0/RP0/CPU0:router#dir disk0:/V6copy Directory of disk0: 70144 -rwx 308413 Sun Oct 16 23:06:52 2011 V6copy 2102657024 bytes total (1537638400 bytes free)In the following example, user admin is uploading the file v6copy from disk0: to disk0a:/v6back on a local SFTP server using an IPv6 address:
RP/0/RP0/CPU0:router#sftp disk0:/V6copy admin@[2:2:2::2]:disk0a:/v6back Connecting to 2:2:2::2... Password: /disk0:/V6copy Transferred 308413 Bytes 308413 bytes copied in 0 sec (421329)bytes/sec RP/0/RP0/CPU0:router#dir disk0a:/v6back Directory of disk0a: 66016 -rwx 308413 Sun Oct 16 23:07:28 2011 v6back 2102788096 bytes total (2098987008 bytes free)In the following example, user admin is downloading the file sampfile from disk0: to disk0a:/sampfile_v4 on a local SFTP server using an IPv4 address:
RP/0/RP0/CPU0:router#sftp admin@2.2.2.2:disk0:/sampfile disk0a:/sampfile_v4 Connecting to 2.2.2.2... Password: disk0:/sampfile Transferred 986 Bytes 986 bytes copied in 0 sec (493000)bytes/sec RP/0/RP0/CPU0:router#dir disk0a:/sampfile_v4 Directory of disk0a: 131520 -rwx 986 Tue Oct 18 05:37:00 2011 sampfile_v4 502710272 bytes total (502001664 bytes free)In the following example, user admin is uploading the file sampfile_v4 from disk0a: to disk0:/sampfile_back on a local SFTP server using an IPv4 address:
RP/0/RP0/CPU0:router#sftp disk0a:/sampfile_v4 admin@2.2.2.2:disk0:/sampfile_back Connecting to 2.2.2.2... Password: disk0a:/sampfile_v4 Transferred 986 Bytes 986 bytes copied in 0 sec (564000)bytes/sec RP/0/RP0/CPU0:router#dir disk0:/sampfile_back Directory of disk0: 121765 -rwx 986 Tue Oct 18 05:39:00 2011 sampfile_back 524501272 bytes total (512507614 bytes free)sftp (Interactive Mode)
sftp [ username @ host : remote-filenam e ] [ source-interface type interface-path-id ] [ vrf vrf-name ]
Syntax Description
username
(Optional) Name of the user performing the file transfer. The at symbol (@) following the username is required.
hostname:remote-filename
(Optional) Name of the Secure Shell File Transfer Protocol (SFTP) server. The colon (:) following the hostname is required.
source-interface
(Optional) Specifies the source IP address of a selected interface for all outgoing SSH connections.
type
Interface type. For more information, use the question mark (?) online help function.
interface-path-id
Physical interface or virtual interface.
Note Use the show interfaces command in EXEC mode to see a list of all interfaces currently configured on the router.
For more information about the syntax for the router, use the question mark (?) online help function.
vrf vrf-name
Specifies the name of the VRF associated with the source interface.
Command Default
If no username argument is provided, the login name on the router is used. If no hostname argument is provided, the file is considered local.
Command History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.
The SFTP client, in the interactive mode, creates a secure SSH channel where the user can enter any supported command. When a user starts the SFTP client in an interactive mode, the SFTP client process creates a secure SSH channel and opens an editor where user can enter any supported command.
More than one request can be sent to the SFTP server to execute the commands. While there is no limit on the number of 'non-acknowledged' or outstanding requests to the server, the server might buffer or queue these requests for convenience. Therefore, there might be a logical sequence to the order of requests.
The following unix based commands are supported in the interactive mode:
- bye
- cd <path>
- chmod <mode> <path>
- exit
- get <remote-path> [local-path]
- help
- ls [-alt] [path]
- mkdir <path>
- put <local-path> [remote-path]
- pwd
- quit
- rename <old-path> <new-path>
- rmdir <path>
- rm <path>
The following commands are not supported:
Task ID
In the following example, user admin is downloading and uploading a file from/to an external SFTP server using an IPv6 address:
RP/0/RP0/CPU0:router#sftp admin@[2:2:2::2] Connecting to 2:2:2::2... Password: sftp> pwd Remote working directory: / sftp> cd /auto/tftp-server1-users5/admin sftp> get frmRouter /disk0:/frmRouterdownoad /auto/tftp-server1-users5/admin/frmRouter Transferred 1578 Bytes 1578 bytes copied in 0 sec (27684)bytes/sec sftp> put /disk0:/frmRouterdownoad againtoServer /disk0:/frmRouterdownoad Transferred 1578 Bytes 1578 bytes copied in 0 sec (14747)bytes/sec sftp>In the following example, user abc is downloading and uploading a file from/to an external SFTP server using an IPv4 address:
RP/0/RP0/CPU0:router#sftp abc@2.2.2.2 Connecting to 2.2.2.2... Password: sftp> pwd Remote working directory: / sftp> cd /auto/tftp-server1-users5/abc sftp> get frmRouter /disk0:/frmRouterdownoad /auto/tftp-server1-users5/abc/frmRouter Transferred 1578 Bytes 1578 bytes copied in 0 sec (27684)bytes/sec sftp> put /disk0:/frmRouterdownoad againtoServer /disk0:/frmRouterdownoad Transferred 1578 Bytes 1578 bytes copied in 0 sec (14747)bytes/sec sftp>show ssh
Command History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.
Use the show ssh command to display all incoming and outgoing Secure Shell (SSH) Version 1 (SSHv1) and SSH Version 2 (SSHv2) connections.
Task ID
This is sample output from the show ssh command when SSH is enabled:
RP/0/RP0/CPU0:router# show ssh SSH version: Cisco-2.0 id pty location state userid host ver ------------------------------------------------------------------------ Incoming sessions 0 vty0 0//CPU0 SESSION_OPEN cisco 172.19.72.182 v2 1 vty1 0//CPU0 SESSION_OPEN cisco 172.18.0.5 v2 2 vty2 0//CPU0 SESSION_OPEN cisco 172.20.10.3 v1 3 vty3 0//CPU0 SESSION_OPEN cisco 3333::50 v2 Outgoing sessions 1 0//CPU0 SUSPENDED root 172.19.72.182 v2This table describes significant fields shown in the display.
Table 1 show ssh Field Descriptions Field
Description
Session identifier for the incoming and outgoing SSH connections.
pty
pty-id allocated for the incoming session. Null for outgoing SSH connection.
location
Specifies the location of the SSH server for an incoming connection. For an outgoing connection, location specifies from which route processor the SSH session is initiated.
state
The SSH state that the connection is currently in.
userid
Authentication, authorization and accounting (AAA) username used to connect to or from the router.
host
IP address of the remote peer.
ver
Specifies if the connection type is SSHv1 or SSHv2.
authentication
Specifies the type of authentication method chosen by the user.
Related Commands
show ssh session details
To display the details for all incoming and outgoing Secure Shell Version 2 (SSHv2) connections, use the show ssh session details command.
Command History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.
Use the show ssh session details command to display a detailed report of the SSHv2 connections to or from the router, including the cipher chosen for the specific session.
Task ID
The following is sample output from the show ssh session details command to display the details for all the incoming and outgoing SSHv2 connections:
RP/0/RP0/CPU0:router# show ssh session details SSH version: Cisco-2.0 session key-exchange pubkey incipher outcipher inmac outmac ------------------------------------------------------------------------------- Incoming Session 0 diffie-hellman ssh-dss 3des-cbc 3des-cbc hmac-md5 hmac-md5 Outgoing connection 1 diffie-hellman ssh-dss 3des-cbc 3des-cbc hmac-md5 hmac-md5This table describes the significant fields shown in the display.
Table 2 show ssh session details Field Descriptions Field
Description
session
Session identifier for the incoming and outgoing SSH connections.
key-exchange
Key exchange algorithm chosen by both peers to authenticate each other.
pubkey
Public key algorithm chosen for key exchange.
incipher
Encryption cipher chosen for the Rx traffic.
outcipher
Encryption cipher chosen for the Tx traffic.
inmac
Authentication (message digest) algorithm chosen for the Rx traffic.
outmac
Authentication (message digest) algorithm chosen for the Tx traffic.
ssh
To start the Secure Shell (SSH) client connection and enable an outbound connection to an SSH server, use the ssh command.
Syntax Description
ipv4-address
IPv4 address in A:B:C:D format.
ipv6-address
IPv6 address in X:X::X format.
hostname
Hostname of the remote node. If the hostname has both IPv4 and IPv6 addresses, the IPv6 address is used.
usernameuser-id
(Optional) Specifies the username to use when logging in on the remote networking device running the SSH server. If no user ID is specified, the default is the current user ID.
cipher
source interface
(Optional) Specifies the source IP address of a selected interface for all outgoing SSH connections.
type
Interface type. For more information, use the question mark (?)online help function.
interface-path-id
Physical interface or virtual interface.
Note Use theshowinterfaces command in XR EXEC mode to see a list of all interfaces currently configured on the router.
For more information about the syntax for the router, use the question mark(?)online help function.
command
(Optional) Specifies a remote command. Adding this keyword prompts the SSHv2 server to parse and execute thesshcommand in non-interactive mode instead of initiating the interactive session.
Command History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.
Use the ssh command to make an outbound client connection. The SSH client tries to make an SSHv2 connection to the remote peer. If the remote peer supports only the SSHv1 server, it internally spawns an SSHv1 connection to the remote server. The process of the remote peer version detection and spawning the appropriate client connection is transparent to the user.
If is specified in the ssh command, the ssh interface takes precedence over the interface specified in the ssh client source-interface ssh client source-interfacecommand.
Use the command keyword to enable the SSHv2 server to parse and execute the ssh command in non-interactive mode instead of initiating an interactive session.
Task ID
The following sample output is from the ssh command to enable an outbound SSH client connection:
RP/0/RP0/CPU0:router# sshusername userabc Password: Remote-host>ssh client knownhost
To authenticate a server public key (pubkey), use the ssh client knownhost command. To disable authentication of a server pubkey, use the no form of this command.
Syntax Description
device:/ filename
Complete path of the filename (for example, slot0:/server_pubkey). The colon (:) and slash (/) are required.
Command History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.
The server pubkey is a cryptographic system that uses two keys at the client end—a public key known to everyone and a private, or secret, key known only to the owner of the keys. In the absence of certificates, the server pubkey is transported to the client through an out-of-band secure channel. The client stores this pubkey in its local database and compares this key against the key supplied by the server during the early stage of key negotiation for a session-building handshake. If the key is not matched or no key is found in the local database of the client, users are prompted to either accept or reject the session.
The operative assumption is that the first time the server pubkey is retrieved through an out-of-band secure channel, it is stored in the local database. This process is identical to the current model adapted by Secure Shell (SSH) implementations in the UNIX environment.
Task ID
The following sample output is from the ssh client knownhost command:
RP/0/RP0/CPU0:router# configure RP/0/RP0/CPU0:router(config)# ssh client knownhost disk0:/ssh.knownhost RP/0/RP0/CPU0:router(config)# commit RP/0/RP0/CPU0:router# ssh host1 username user1234 Host key not found from the list of known hosts. Are you sure you want to continue connecting (yes/no)? yes Password: RP/0/RP0/CPU0:host1# exit RP/0/RP0/CPU0:router# ssh host1 username user1234ssh client source-interface
To specify the source IP address of a selected interface for all outgoing Secure Shell (SSH) connections, use the ssh client source-interface command. To disable use of the specified interface IP address, use the no form of this command.
ssh client source-interface type interface-path-id
no ssh client source-interface type interface-path-id
Syntax Description
type
Interface type. For more information, use the question mark (?) online help function.
interface-path-id
Physical interface or virtual interface.
Note Use the show interfaces command to see a list of all interfaces currently configured on the router.
For more information about the syntax for the router, use the question mark (?) online help function.
Command History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.
Use the ssh client source-interface command to set the IP address of the specified interface for all outgoing SSH connections. If this command is not configured, TCP chooses the source IP address when the socket is connected, based on the outgoing interface used—which in turn is based on the route required to reach the server. This command applies to outbound shell over SSH as well as Secure Shell File Transfer Protocol (SFTP) sessions, which use the ssh client as a transport.
The source-interface configuration affects connections only to the remote host in the same address family. The system database (Sysdb) verifies that the interface specified in the command has a corresponding IP address (in the same family) configured.
Task ID
ssh client vrf
To configure a new VRF for use by the SSH client, use the ssh client vrf command. To remove the specified VRF, use the no form of this command.
Syntax Description
Command History
Command History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.
An SSH client can have only one VRF.
If a specific VRF is not configured for the SSH client, the default VRF is assumed when applying other SSH client-related commands, such as ssh client knownhost or ssh client source-interface.
Task ID
ssh server
To bring up the Secure Shell (SSH) server and to configure one or more VRFs for its use, use the ssh server command. To stop the SSH server from receiving any further connections for the specified VRF, use the no form of this command.
Syntax Description
vrf vrf-name
Specifies the name of the VRF to be used by the SSH server. The maximum VRF length is 32 characters.
Note If no VRF is specified, the default VRF is assumed.
v2
Forces the SSH server version to be only 2.
Command Default
The default SSH server version is 2 (SSHv2), which falls back to 1 (SSHv1) if the incoming SSH client connection is set to SSHv1.
Command History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.
An SSH server must be configured at minimum for one VRF. If you delete all configured VRFs, including the default, the SSH server process stops. If you do not configure a specific VRF for the SSH client when applying other commands, such as ssh client knownhost or ssh client source-interface, the default VRF is assumed.
The SSH server listens for an incoming client connection on port 22. This server handles both Secure Shell Version 1 (SSHv1) and SSHv2 incoming client connections for both IPv4 and IPv6 address families. To accept only Secure Shell Version 2 connections, use the ssh server v2 command.
To verify that the SSH server is up and running, use the show process sshd command.
Task ID
In the following example, the SSH server is brought up to receive connections for VRF “green”:
RP/0/RP0/CPU0:router# configure RP/0/RP0/CPU0:router(config)# sshRelated Commands
Command
Description
show processes
Displays information about the SSH server.
Forces the SSH server version to be only 2 (SSHv2).
ssh server dscp <value from 0 - 63>
SSH server supports setting DSCP value in the outgoing packets. If not configured, the default DSCP value set in packets is 16 (for both client and server).
ssh server logging
To enable SSH server logging, use the ssh server logging command. To discontinue SSH server logging, use the no form of this command.
Command History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.
Once you configure the logging, the following messages are displayed:
- Warning: The requested term-type is not supported
- SSH v2 connection from %s succeeded (user:%s, cipher:%s, mac:%s, pty:%s)
The warning message appears if you try to connect using an unsupported terminal type. Routers running the Cisco IOS XR software support only the vt100 terminal type.
The second message confirms a successful login.
Task ID
ssh server rate-limit
To limit the number of incoming Secure Shell (SSH) connection requests allowed per minute, use the ssh server rate-limit command. To return to the default value, use the no form of this command.
Syntax Description
rate-limit
Number of incoming SSH connection requests allowed per minute. Range is from 1 to 120.
When setting it to 60 attempts per minute, it basically means that we can only allow 1 per second. If you set up 2 sessions at the same time from 2 different consoles, one of them will get rate limited. This is connection attempts to the ssh server, not bound per interface/username or anything like that. So value of 30 means 1 session per 2 seconds and so forth.
Command History
Command History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.
Use the ssh server rate-limit command to limit the incoming SSH connection requests to the configured rate. Any connection request beyond the rate limit is rejected by the SSH server. Changing the rate limit does not affect established SSH sessions.
If, for example, the rate-limit argument is set to 30, then 30 requests are allowed per minute, or more precisely, a two-second interval between connections is enforced.
Task ID
ssh server session-limit
To configure the number of allowable concurrent incoming Secure Shell (SSH) sessions, use the ssh server session-limit command. To return to the default value, use the no form of this command.
Syntax Description
Command History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.
Use the ssh server session-limit command to configure the limit of allowable concurrent incoming SSH connections. Outgoing connections are not part of the limit.
Task ID
ssh server v2
To force the SSH server version to be only 2 (SSHv2), use the ssh server v2 command. To bring down an SSH server for SSHv2, use the no form of this command.
Command History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.
Only SSHv2 client connections are allowed.
Task ID
ssh timeout
To configure the timeout value for authentication, authorization, and accounting (AAA) user authentication, use the ssh timeout command. To set the timeout value to the default time, use the no form of this command.
Syntax Description
Command History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.
Use the ssh timeout command to configure the timeout value for user authentication to AAA. If the user fails to authenticate itself within the configured time to AAA, the connection is aborted. If no value is configured, the default value of 30 seconds is used.
Task ID