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This chapter describes the function and displays the syntax for basic system management commands. For more information about defaults and usage guidelines, see the corresponding chapter of the Configuration Fundamentals Command Reference.
To create a command alias, use the alias global configuration command. Use the no form of this command to delete all aliases in a command mode or to delete a specific alias, and to revert to the original command syntax.
alias mode alias-name alias-command-line| mode | Command mode of the original and alias commands. |
| alias-name | Command alias. |
| alias-command-line | Original command syntax. |
To set the system calendar, use one of the formats of the calendar set EXEC command.
calendar set hh:mm:ss day month year| hh:mm:ss | Current time in hours (military format), minutes, and seconds. |
| day | Current day (by date) in the month. |
| month | Current month (by name). |
| year | Current year (no abbreviation). |
To configure a router as a time source for a network based on its calendar, use the clock calendar-valid global configuration command. Use the no form of this command to specify that the calendar is not an authoritative time source.
clock calendar-validTo manually read the calendar into the system clock, use the clock read-calendar EXEC command.
clock read-calendarTo manually set the system clock, use one of the formats of the clock set EXEC command.
clock set hh:mm:ss day month year| hh:mm:ss | Current time in hours (military format), minutes, and seconds. |
| day | Current day (by date) in the month. |
| month | Current month (by name). |
| year | Current year (no abbreviation). |
To configure the system to automatically switch to summer time (daylight savings time), use one of the formats of the clock summer-time global configuration command. Use the no form of this command to configure the Cisco IOS software not to automatically switch to summer time.
clock summer-time zone recurring [week day month hh:mm week day month hh:mm [offset]]| zone | Name of the time zone (PDT,...) to be displayed when summer time is in effect. |
| recurring | Indicates that summer time should start and end on the corresponding specified days every year. |
| date | Indicates that summer time should start on the first specific date listed in the command and end on the second specific date in the command. |
| week | Week of the month (1 to 5 or last). |
| day | Day of the week (Sunday, Monday,...). |
| date | Date of the month (1 to 31). |
| month | Month (January, February,...). |
| year | Year (1993 to 2035). |
| hh:mm | Time (military format) in hours and minutes. |
| offset | (Optional) Number of minutes to add during summer time (default is 60). |
To set the time zone for display purposes, use the clock timezone global configuration command. To set the time to Coordinated Universal Time (UTC), use the no form of this command.
clock timezone zone hours [minutes]| zone | Name of the time zone to be displayed when standard time is in effect. |
| hours | Hours offset from UTC. |
| minutes | (Optional) Minutes offset from UTC. |
To set the calendar from the system clock, use the clock update-calendar EXEC command.
clock update-calendarTo generate a configuration that is compatible with an earlier Cisco IOS release, use the downward-compatible-config global configuration command. To remove this feature, use the no form of this command.
downward-compatible-config version| version | Cisco IOS Release number, not earlier than 10.2. |
To specify or modify the host name for the network server, use the hostname global configuration command. The host name is used in prompts and default configuration filenames. The setup command facility also prompts for a host name at startup.
hostname name| name | New host name for the network server. |
To access the BOOTP service available from hosts on the network, use the ip bootp server global configuration command. Use the no form of the command to disable these services.
ip bootp serverUse the ip telnet source-interface global configuration command to allow a user to select an address of an interface as the source address for Telnet connections. Use the no form of this command to reset the source address to the default for each connection.
ip telnet source-interface interface| interface | The interface whose address is to be used as the source for Telnet connections. |
Use the ip tftp source-interface global configuration command to allow a user to select the interface whose address will be used as the source address for TFTP connections.
ip tftp source-interface interface| interface | The interface whose address is to be used as the source for TFTP connections. |
To control access to the system's Network Time Protocol (NTP) services, use the ntp access-group global configuration command. To remove access control to the system's NTP services, use the no form of this command.
ntp access-group {query-only | serve-only | serve | peer} access-list-number| query-only | Allows only NTP control queries. See RFC 1305 (NTP version 3). |
| serve-only | Allows only time requests. |
| serve | Allows time requests and NTP control queries, but does not allow the system to synchronize to the remote system. |
| peer | Allows time requests and NTP control queries and allows the system to synchronize to the remote system. |
| access-list-number | Number (1 to 99) of a standard IP access list. |
To enable Network Time Protocol (NTP) authentication, use the ntp authenticate global configuration command. Use the no form of this command to disable the feature.
ntp authenticateTo define an authentication key for Network Time Protocol (NTP), use the ntp authentication-key global configuration command. Use the no form of this command to remove the authentication key for NTP.
ntp authentication-key number md5 value| number | Key number (1 to 4294967295). |
| md5 | Authentication key. Message authentication support is provided using the Message Digest (MD5) algorithm. The key type md5 is currently the only key type supported. |
| value | Key value (an arbitrary string of up to eight characters). |
To specify that a specific interface should send Network Time Protocol (NTP) broadcast packets, use the ntp broadcast interface configuration command. Use the no form of this command to disable this capability.
ntp broadcast [version number]| version number | (Optional) Number from 1 to 3 indicating the NTP version. |
To allow the system to receive NTP broadcast packets on an interface, use the ntp broadcast client interface configuration command. Use the no form of this command to disable this capability.
ntp broadcast clientTo set the estimated round-trip delay between the Cisco IOS software and a Network Time Protocol (NTP) broadcast server, use the ntp broadcastdelay global configuration command. Use the no form of this command to revert to the default value.
ntp broadcastdelay microseconds| microseconds | Estimated round-trip time (in microseconds) for NTP broadcasts. The range is from 1 to 999999. |
| value | Amount to add to the system clock for each clock hardware tick (in units of 2-32 seconds). |
To prevent an interface from receiving Network Time Protocol (NTP) packets, use the ntp disable interface configuration command. To enable receipt of NTP packets on an interface, use the no form of this command.
ntp disableTo configure the Cisco IOS software as a Network Time Protocol (NTP) master clock to which peers synchronize themselves when an external NTP source is not available, use the ntp master global configuration command. To disable the master clock function, use the no form of this command.
ntp master [stratum]| stratum | (Optional) Number from 1 to 15. Indicates the NTP stratum number that the system will claim. |
To configure the system clock to synchronize a peer or to be synchronized by a peer, use the
ntp peer global configuration command. To disable this capability, use the no form of this command.
| ip-address | IP address of the peer providing, or being provided, the clock synchronization. |
| version | (Optional) Defines the Network Time Protocol (NTP) version number. |
| number | (Optional) NTP version number (1 to 3). |
| key | (Optional) Defines the authentication key. |
| keyid | (Optional) Authentication key to use when sending packets to this peer. |
| source | (Optional) Names the interface. |
| interface | (Optional) Name of the interface from which to pick the IP source address. |
| prefer | (Optional) Makes this peer the preferred peer that provides synchronization. |
To allow the system clock to be synchronized by a time server, use the ntp server global configuration command. To disable this capability, use the no form of this command.
ntp server ip-address [version number] [key keyid] [source interface] [prefer]| ip-address | IP address of the time server providing the clock synchronization. |
| version | (Optional) Defines the Network Time Protocol (NTP) version number. |
| number | (Optional) NTP version number (1 to 3). |
| key | (Optional) Defines the authentication key. |
| keyid | (Optional) Authentication key to use when sending packets to this peer. |
| source | (Optional) Identifies the interface from which to pick the IP source address. |
| interface | (Optional) Name of the interface from which to pick the IP source address. |
| prefer | (Optional) Makes this server the preferred server that provides synchronization. |
To use a particular source address in Network Time Protocol (NTP) packets, use the ntp source global configuration command. Use the no form of this command to remove the specified source address.
ntp source type number| type | Type of interface. |
| number | Number of the interface. |
To authenticate the identity of a system to which Network Time Protocol (NTP) will synchronize, use the ntp trusted-key global configuration command. Use the no form of this command to disable authentication of the identity of the system.
ntp trusted-key key-number| key-number | Key number of authentication key to be trusted. |
To periodically update the calendar from Network Time Protocol (NTP), use the ntp update-calendar global configuration command. Use the no form of this command to disable this feature.
ntp update-calendarTo customize the prompt, use the prompt global configuration command. To revert to the default prompt, use the no form of this command.
prompt string| string | Prompt. |
To specify that line numbers be displayed and interpreted as decimal numbers rather than octal numbers, use the service decimal-tty global configuration command. Use the no form of this command to restore the default.
service decimal-ttyTo delay the startup of the EXEC on noisy lines, use the service exec-wait global configuration command. Use the no form of this command to disable this feature.
service exec-waitTo allow Finger protocol requests (defined in RFC 742) to be made of the network server, use the service finger global configuration command. This service is equivalent to issuing a remote show users command. Use the no form of this command to remove this service.
service fingerTo hide addresses while trying to establish a Telnet session, use the service hide-telnet-address global configuration command. Use the no form of this command to remove this service.
service hide-telnet-addressTo display the configuration prompt (config), use the service prompt config global configuration command. Use the no form of this command to remove the configuration prompt.
service prompt configTo access minor TCP/IP services available from hosts on the network, use the service tcp-small-servers global configuration command. Use the no form of the command to disable these services.
service tcp-small-serversTo set the TCP window to zero (0) when the Telnet connection is idle, use the service telnet-zero-idle global configuration command. Use the no form of this command to disable this feature.
service telnet-zero-idleTo access minor User Datagram Protocol (UDP) services available from hosts on the network, use the service udp-small-servers global configuration command. Use the no form of the command to disable these services.
service udp-small-serversTo display all alias commands, or the alias commands in a specified mode, use the show aliases EXEC command.
show aliases [mode]| mode | (Optional) Command mode. |
To display the calendar hardware setting, use the show calendar EXEC command:
show calendarTo display the system clock, use the show clock EXEC command.
show clock [detail]| detail | (Optional) Indicates the clock source (NTP, VINES, system calendar, and so forth) and the current summer-time setting (if any). |
To show the status of Network Time Protocol (NTP) associations, use the show ntp associations EXEC command.
show ntp associations [detail]| detail | (Optional) Shows detailed information about each NTP association. |
To show the status of Network Time Protocol (NTP), use the show ntp status EXEC command.
show ntp statusUse the show sntp EXEC command on a Cisco 1003, Cisco 1004, or Cisco 1005 router to show information about the Simple Network Time Protocol (SNTP).
show sntpUse the sntp broadcast client global configuration command to configure a Cisco 1003, Cisco 1004, or Cisco 1005 router to use the Simple Network Time Protocol (SNTP) to accept Network Time Protocol (NTP) traffic from any broadcast server. The no form of the command prevents the router from accepting broadcast traffic.
sntp broadcast clientUse the sntp server global configuration command to configure a Cisco 1003, Cisco 1004, or Cisco 1005 router to use the Simple Network Time Protocol (SNTP) to request and accept Network Time Protocol (NTP) traffic from a time server. The no form of the command removes a server from the list of NTP servers.
sntp server {address | hostname} [version number]| address | IP address of the time server. |
| hostname | Hostname of the time server. |
| version number | (Optional) Version of NTP to use. The default is 1. |
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