Administrator Guide

Command Authorization
The AAA command authorization feature congures the system to send each conguration command to a TACACS server for
authorization before it is added to the running conguration.
By default, the AAA authorization commands congure the system to check both EXEC mode and CONFIGURATION mode commands.
Use the no aaa authorization config-commands command to enable only EXEC mode command checking.
If rejected by the AAA server, the command is not added to the running cong, and a message displays:
04:07:48: %SYSTEM-P:CP %SEC-3-SEC_AUTHORIZATION_FAIL: Authorization failure Command
authorization failed for user (denyall) on vty0 ( 10.11.9.209 )
Protection from TCP Tiny and Overlapping Fragment
Attacks
Tiny and overlapping fragment attack is a class of attack where congured ACL entries — denying TCP port-specic trac — is bypassed
and trac is sent to its destination although denied by the ACL.
RFC 1858 and 3128 proposes a countermeasure to the problem. This countermeasure is congured into the line cards and enabled by
default.
Enabling SCP and SSH
Secure shell (SSH) is a protocol for secure remote login and other secure network services over an insecure network. The Dell Neetworking
OS is compatible with SSH versions 1.5 and 2, both the client and server modes. SSH sessions are encrypted and use authentication.
For details about the command syntax, refer to the Security chapter in the Dell Networking OS Command Line Interface Reference Guide.
SCP is a remote le copy program that works with SSH and is supported on the switch.
NOTE
: The Windows-based WinSCP client software is not supported for secure copying between a PC and a Dell Networking
OS-based system. Unix-based SCP client software is supported.
To use the SSH client, use the following command.
• Open an SSH connection and specifying the host name, username, port number, and version of the SSH client.
EXEC Privilege mode
ssh {hostname} [-l username | -p port-number | -v {1 | 2}
hostname is the IP address or host name of the remote device. Enter an IPv4 or IPv6 address in dotted decimal format (A.B.C.D).
• Congure the Dell Networking system as an SCP/SSH server.
CONFIGURATION mode
ip ssh server {enable | port port-number}
• Congure the Dell Networking system as an SSH server that uses only version 1 or 2.
CONFIGURATION mode
ip ssh server version {1|2}
• Display SSH connection information.
EXEC Privilege mode
show ip ssh
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Security