Remote port

The probe checks accessibility of a remote port.

Settings example

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Field Description

Protocol

Protocol of the checked port, TCP or UDP.

Hostname

IP address or DNS name of the remote host to check.

Port

The port to check.

Data

Additional test data which can be sent to remote port while the check is performing.

Timeout

Maximum time to perform the check in milliseconds.

Period

How often to perform the check (60 seconds by default).

Result

After the check has been done result is displayed in the Data table:

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Field Description

success

Check result:

  • true - the port is accessible;

  • false - the port is not accessible.

errorMessage

Messages about the check errors or port inaccessibility reasons.

Command-line utility

This check is the counterpart of the terminal command netcat:

$ netcat -zv saymon.info 80
Connection to saymon.info 80 port [tcp/http] succeeded!

$ netcat -zvu saymon.info 80
Connection to saymon.info 80 port [udp/http] succeeded!

Known problems and errors

Sensor error! [net.sf.oval.ConstraintViolation: must be between 1 and 65535 inclusive]

Specified Port value is out of the valid range from 1 to 65535.

Check the correctness of the data in the field Port.

messageError - UnknownHostException: http://saymon.info

The specified Hostname is not found (getaddrinfo: Name or service not known).

Probable reasons:

  • the specified hostname is incorrect;

  • the specified hostname is not available from the network, where the check was performed;

  • the specified hostname contains "http://" or "https://" protocol prefix.

Check the correctness of the specified hostname.

Check the availability of the specified hostname, performing the command netcat on the terminal, where the agent is installed.

Do not specify prefixes in the field Hostname.