Reference Guide

To delete a TACACS+ server host, use the no tacacs-server host {hostname | ip-address} command.
freebsd2# telnet 2200:2200:2200:2200:2200::2202
Trying 2200:2200:2200:2200:2200::2202...
Connected to 2200:2200:2200:2200:2200::2202.
Escape character is '^]'.
Login: admin
Password:
Dell#
Command Authorization
The AAA command authorization feature configures the system to send each configuration command to a TACACS server for
authorization before it is added to the running configuration.
By default, the AAA authorization commands configure 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 config, 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 configured ACL entries — denying TCP port-specific traffic —
is bypassed and traffic is sent to its destination although denied by the ACL.
RFC 1858 and 3128 proposes a countermeasure to the problem. This countermeasure is configured 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 file 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).
● Configure the Dell Networking system as an SCP/SSH server.
CONFIGURATION mode
ip ssh server {enable | port port-number}
● Configure the Dell Networking system as an SSH server that uses only version 1 or 2.
676
Security