Concepts Checks TCP

TCP Check

The TCP check attempts to open a TCP connection to a host and port. It doesn't speak any application protocol — it just confirms the port is open and accepting connections.

Source: TcpCheckExecutor.cs · TcpCheckData.cs

What it verifies

• The host is reachable on the network
• The specified port is open and accepts TCP connections
• The connection completes within the timeout (default 5 seconds)

Common use cases

Database port

{ "host": "db.internal", "port": 5432 }

Redis

{ "host": "redis.internal", "port": 6379 }

SMTP

{ "host": "mail.example.com", "port": 587 }

Custom service port

{ "host": "worker.internal", "port": 8080, "timeout": 3000 }

Configuration

Field	Default	Description
host	—	Hostname or IP to connect to (required)
port	—	TCP port number (required)
timeout	5000	Milliseconds before the connection attempt is aborted

Statuses

Status	When
UP	Connection established successfully
DOWN	Connection timed out or refused
FAILURE	Host or port not configured

Latency

Measured from the start of the connection attempt to when the connection is established.

Related

• Checks — common settings (schedule, thresholds, criticality)
• Ping Check — use Ping to check raw reachability before TCP