Telnet Service Options

October 28, 2008 at 3:04 pm | Posted in System Management | Leave a comment

12.12 Telnet Service Options

  • Configure R3 to source all telnet sessions from its Loopback0 interface, and to use a marking of IP Precedence 3 for these packets.
  • Idle outgoing telnet sessions should signal the remote host to pause output.
  • Display the message “Sorry, your connection failed” when a telnet connection to the above host fails.


Rack1R3#sh run

service telnet-zeroidle
ip telnet source-interface Loopback0
ip telnet tos 60
ip telnet quiet
ip telnet hidden hostnames
ip telnet hidden addresses

ip host R4
busy-message R4 ^CSorry, your connection failed^C

Rack1R3(config)#service ?
  alignment              Control alignment correction and logging
  compress-config        Compress the nvram configuration file
  config                 TFTP load config files
  dhcp                   Enable DHCP server and relay agent
  disable-ip-fast-frag   Disable IP particle-based fast fragmentation
  exec-callback          Enable exec callback
  exec-wait              Delay EXEC startup on noisy lines
  finger                 Allow responses to finger requests
  hide-telnet-addresses  Hide destination addresses in telnet command
  linenumber             enable line number banner for each exec
  nagle                  Enable Nagle's congestion control algorithm
  old-slip-prompts       Allow old scripts to operate with slip/ppp
  pad                    Enable PAD commands
  password-encryption    Encrypt system passwords
  prompt                 Enable mode specific prompt
  pt-vty-logging         Log significant VTY-Async events
  sequence-numbers       Stamp logger messages with a sequence number
  slave-log              Enable log capability of slave IPs
  tcp-keepalives-in      Generate keepalives on idle incoming network
  tcp-keepalives-out     Generate keepalives on idle outgoing network
  tcp-small-servers      Enable small TCP servers (e.g., ECHO)
  telnet-zeroidle        Set TCP window 0 when connection is idle
  timestamps             Timestamp debug/log messages
  udp-small-servers      Enable small UDP servers (e.g., ECHO)

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