DELL S50V User Manual

Security | 935

To delete a TACACS+ server host, use the

no tacacs-server host

{

hostname

ip-address

} command.

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 command

no aaa authorization config-commands

to enable

only EXEC mode command checking.

If rejected by the AAA server, the command is not added to the running config, and messages similar to

Message 1

are displayed.

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—can be bypassed, and traffic can be 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.

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.

Message 1 Configuration Command Rejection

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 )

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 '^]'.

Password:

FTOS#