Creating a TCP monitor

The NS1 monitoring solution allows you to create monitors (DNS, PING, HTTP/S, or TCP) to track the health and performance of a specified device or endpoint.

This article explains the process for setting up a TCP monitor and connecting it to answer metadata. Server/device TCP monitoring tracks the availability and response time of a TCP server from a local network — for example if a TCP server is deployed within an intranet and is not accessible outside of it.

Step 1: Create a TCP monitor.

1. In the NS1 portal, navigate to the Monitors tab.
2. Click Add a Monitor.

3. Select TCP from the drop-down menu in the upper-left corner.

   
   
   

4. Under Configuration:

   Name	(Required) Nominal label for the TCP monitor.
   Monitor Paused	Toggle the switch to activate or deactivate the monitor. By default, this option is disabled meaning the monitor is active.
   Notifications On	Toggle the switch to enable or disable notifications related to this monitor. By default, this option is enabled meaning notifications are active.
   Monitoring Regions	Select the locations from which monitoring will be executed.
   Policy	Select one of the following from the drop-down menu: Quorum: The host is marked “down” if tests conducted from a majority of the monitoring regions do not pass the “up” conditions.’ All: The host is marked “down” if tests conducted from all of the monitoring regions do not pass the “up” conditions. One: The host is marked “down” if tests conducted from a single monitoring region do not pass the “up” conditions.
   Frequency	(Required) Enter the amount of time in seconds between each monitoring test conducted in each region. (Minimum: 60s)
   Up Conditions	Click Add Condition to define the condition(s) the hostname must meet in order to be considered "up." First, choose the metric to validate during the test: Timeout - The time (in milliseconds) for the connection between the server and client to open. Output - Output received from any connection if any. Next, choose the comparison operator (=, <, >, etc), and the value to compare. You can add multiple "up" conditions, just note that all conditions must be met in order for a test run to consider the host "up."
   Rapid Recheck	Enable or disable a second, automatic verification test before changing the status of a host. Enabling this option can help prevent false positives.

5. Under TCP Settings:

   Response timeout	Enter the amount of time in milliseconds after connecting to wait for output.
   Connect over IPv6	If enabled, verify that you entered either a fully qualified domain name or IPv6 address. Note: If enabled, the monitor will connect exclusively over IPv6.
   String to send	Enter a string sent to hosts upon connecting. Note that string escapes (e.g., /n) are not permitted.
   Connect timeout	Enter the amount of time in milliseconds before a host should be marked as “failed” or “down.”
   Connect with SSL	Enable or disable the option to connect with SSL.
   IP address or hostname	(Required) Enter the IP address (IPv4 or IPv6) or fully-qualified domain name of the device you would like to monitor.
   TLS verify	Select the checkbox to enable TLS verification on this monitor. NS1 recommends disabling this option if the monitor is failing due to a certificate error, such as an expired certificate for which you do not want this to be used as a failure condition.
   TCP port	(Required) If you are monitoring an HTTP server, set the TCP port to 80. For an HTTPS server, set the TCP port to 443.

6. Once complete, click Save Changes. The new TCP monitor appears in the list.

Step 2: Connect the monitor to an answer using the NS1 Filter Chain.

To complete the setup process, you must connect the monitor to an answer in order to automatically change the “up” metadata to reflect the status of the monitor. That is, when the tested host meets the up conditions, it will change the metadata to up=true. If the tested host does not meet the up conditions, the metadata is automatically changed to up=false.

1. Under Zones, navigate to the record upon which you want to attach the monitor. Then, click into the record to view associated answers.
   
   
   
   
2. Click Create Filter Chain.
   
   
   
   
3. Select or drag-and-drop the Up filter option (and any other desired filters) to the list of active filters.
   
   
   
   
4. Click Save Filter Chain. Now, you can see the Filter Chain configuration to the left of the answer list.
   
   
   
   
5. On the left-hand sidebar showing the Filter Chain configuration, click the UP filter to expand that box and reveal filter-specific metadata options.
   
   
   
   
6. Click the up: unset metadata label beneath the answer to view the Answer Metadata configuration screen.
   
   
   
   
   
   
7. Click the “feed” icon next to the up/down filter setting to reveal a list of available data feeds—including the monitor you created earlier.
   
   
   
   
8. Select the TCP monitor you created earlier, and click Ok.
   
   
   
   
9. Click Save Record to save your changes.
   
   

Now, when the TCP monitor detects a failed endpoint, it automatically adjusts the answer metadata to indicate that the endpoint is “down.” As a result, DNS traffic is steered to better-performing endpoints.