Reference Guide

Command Authorization
The AAA command authorization feature configures FTOS 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: %RPM0-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.
FTOS 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 FTOS Command Line Interface Reference
Guide .
SCP is a remote file copy program that works with SSH and FTOS supports.
NOTE: The Windows-based WinSCP client software is not supported for secure copying between a PC and an
FTOS-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.
CONFIGURATION mode
ip ssh server version {1|2}
• Display SSH connection information.
EXEC Privilege mode
show ip ssh
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