Cisco 2950G 24 Software Configuration Guide - Page 193
Creating an Access Group and Assigning a Basic IP Access List
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Chapter 7 Administering the Switch Managing the System Time and Date Creating an Access Group and Assigning a Basic IP Access List Beginning in privileged EXEC mode, follow these steps to control access to NTP services by using access lists: Step 1 Step 2 Command configure terminal ntp access-group {query-only | serve-only | serve | peer} access-list-number Step 3 access-list access-list-number permit source [source-wildcard] Step 4 Step 5 Step 6 end show running-config copy running-config startup-config Purpose Enter global configuration mode. Create an access group, and apply a basic IP access list. The keywords have these meanings: • query-only-Allows only NTP control queries. • serve-only-Allows only time requests. • serve-Allows time requests and NTP control queries, but does not allow the switch to synchronize to the remote device. • peer-Allows time requests and NTP control queries and allows the switch to synchronize to the remote device. For access-list-number, enter a standard IP access list number from 1 to 99. Create the access list. • For access-list-number, enter the number specified in Step 2. • Enter the permit keyword to permit access if the conditions are matched. • For source, enter the IP address of the device that is permitted access to the switch. • (Optional) For source-wildcard, enter the wildcard bits to be applied to the source. Note When creating an access list, remember that, by default, the end of the access list contains an implicit deny statement for everything if it did not find a match before reaching the end. Return to privileged EXEC mode. Verify your entries. (Optional) Save your entries in the configuration file. The access group keywords are scanned in this order, from least restrictive to most restrictive: 1. peer-Allows time requests and NTP control queries and allows the switch to synchronize itself to a device whose address passes the access list criteria. 2. serve-Allows time requests and NTP control queries, but does not allow the switch to synchronize itself to a device whose address passes the access list criteria. 3. serve-only-Allows only time requests from a device whose address passes the access list criteria. 4. query-only-Allows only NTP control queries from a device whose address passes the access list criteria. 78-14982-01 Catalyst 2950 Desktop Switch Software Configuration Guide 7-41
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