HP procurve series 4100gl Management And Configuration Manual page 447

Cannot Telnet into the switch console from a station on the network:
Telnet access may be disabled by the Inbound Telnet Enabled parameter in
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the System Information screen of the menu interface:
2. Switch Configuration
1. System Information
The switch may not have the correct IP address, subnet mask, or gateway.
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Verify by connecting a console to the switch's Console port and selecting:
2. Switch Configuration
5. IP Configuration
Note: If DHCP/Bootp is used to configure the switch, see the Note, above.
I If you are using DHCP to acquire the IP address for the switch, the IP
address "lease time" may have expired so that the IP address has changed.
For more information on how to "reserve" an IP address, refer to the
documentation for the DHCP application that you are using.
If one or more IP-Authorized managers are configured, the switch allows
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inbound telnet access only to a device having an authorized IP address.
For more information on IP Authorized managers, see see the Access
Security Guide for your switch.
Troubleshooting
Browser or Telnet Access Problems
C-5