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Specifying Operational Mode Commands

You can specify extended regular expressions with the allow-command and deny-command statements to define a user’s access privileges to individual operational commands. Doing so takes precedence over login class permission flags set for a user. You can include one deny-command statement and one allow-command statement in each login class.

To explicitly allow an individual operational mode command that would otherwise be denied, include the allow-command statement at the [edit system login class class-name] hierarchy level:



[edit system login class class-name]
allow-command “regular-expression”;

To explicitly deny an individual operational mode command that would otherwise be allowed, include the deny-command statement at the [edit system login class class-name] hierarchy level:



[edit system login class class-name]
deny-command “regular-expression”;

If the regular expression contains any spaces, operators, or wildcard characters, enclose it in quotation marks. Regular expressions are not case-sensitive.

Use extended regular expressions to specify which operational mode commands are denied or allowed. You specify these regular expressions in the allow-command and deny-command statements at the [edit system login class] hierarchy level, or by specifying attributes specific to JUNOS in your TACACS+ or RADIUS authentication server configuration. You must specify that these regular expressions are sent as the value of Juniper Networks vendor-specific attributes. If regular expressions are received during TACACS+ or RADIUS authentication, they merge with any regular expressions configured on the local router. For information about TACACS+ or RADIUS authentication, see the JUNOS System Basics Configuration Guide.

Command regular expressions implement the extended (modern) regular expressions as defined in POSIX 1003.2. Table 8 lists common regular expression operators.

Table 8: Common Regular Expression Operators to Allow or Deny Operational Mode Commands

Operator	Match...
\|	One of two or more terms separated by the pipe. Each term must be a complete standalone expression enclosed in parentheses ( ), with no spaces between the pipe and the adjacent parentheses. For example, (show system alarms)\|(show system software).
^	At the beginning of an expression, used to denote where the command begins, and where there might be some ambiguity.
$	Character at the end of a command. Used to denote a command that must be matched exactly up to that point. For example, allow-command "show interfaces$" means that the user can issue the show interfaces command but cannot issue the show interfaces detail or show interfaces extensive command.
[ ]	Range of letters or digits. To separate the start and end of a range, use a hyphen ( - ).
( )	A group of commands, indicating a complete, standalone expression to be evaluated; the result is then evaluated as part of the overall expression. Parentheses must always be used in conjunction with pipe operators as explained previously.

If a regular expression contains a syntax error, it becomes invalid, and although the user can log in, the permission granted or denied by the regular expression does not take effect. When regular expressions configured on TACACS+ or RADIUS servers are merged with regular expressions configured on the router and the final expression has a syntax error, the overall result is an invalid regular expression. If a regular expression does not contain any operators, all varieties of the command are allowed. For example, if the following statement is included in the configuration, the user can issue the commands show interfaces detail and show interfaces extensive in addition to showing an individual interface:



allow-command "show interfaces"

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