# TCP Monitor

- Import the `TcpMonitor` construct from `checkly/constructs`.
- When adding `assertions`, always use `TcpAssertionBuilder` class for TCP monitors.
- **Plan-gated properties:** `retryStrategy`, `runParallel`, and higher frequencies are not available on all plans. Check entitlements matching `UPTIME_CHECKS_*` before using these. Omit any property whose entitlement is disabled. See `npx checkly skills manage` for details.

**Reference:** https://www.checklyhq.com/docs/constructs/tcp-monitor/

```typescript
import { AlertEscalationBuilder, Frequency, RetryStrategyBuilder, TcpAssertionBuilder, TcpMonitor } from 'checkly/constructs'

new TcpMonitor('example-tcp-monitor', {
  name: 'Example TCP Monitor',
  degradedResponseTime: 5000,
  maxResponseTime: 5000,
  activated: true,
  locations: [
    'eu-central-1',
    'eu-west-2',
  ],
  frequency: Frequency.EVERY_1H,
  alertEscalationPolicy: AlertEscalationBuilder.runBasedEscalation(1, {
    amount: 0,
    interval: 5,
  }, {
    enabled: false,
    percentage: 10,
  }),
  retryStrategy: RetryStrategyBuilder.noRetries(),
  runParallel: true,
  request: {
    hostname: 'INSERT_HOSTNAME',
    port: 4242,
    ipFamily: 'IPv4',
    assertions: [
      TcpAssertionBuilder.responseTime().lessThan(200),
      TcpAssertionBuilder.responseData().isEmpty(),
    ],
  },
})
```