TCP port monitoring
Not every service speaks HTTP. A port check tells you whether the service is listening and how long the connection takes.
What each check does
- Opens a TCP connection to host:port and measures how long it takes.
- Tries each address the host resolves to, IPv4 and IPv6.
When it alerts
- The connection is refused or does not open within the timeout.
Example
mail.example.com:25Good to know
- Check from several regions to tell a firewall or routing problem from a service that is down.
- For PostgreSQL, MySQL and Redis, use the database monitors, which check that the right server answers.
On every monitor
- Alerts by email, Slack, Discord, Teams, Telegram, PagerDuty, webhooks, Lark, ntfy and the mobile app.
- Recovery thresholds, so an incident closes only after the service has answered several times in a row.
- Dependencies: a monitor that depends on another stays quiet while that one is down.
- Maintenance windows, incident history and public status pages built from the same monitors.
Try it on the Free plan
The Free plan includes 3 monitors checked every 5 minutes, with every alert channel. No card needed.
Questions
Is an open port enough to say a service works?
It proves the process is listening, not that it answers correctly. Where a service has a protocol of its own, a check that speaks it tells you more; for HTTP, use a website or API monitor.
Can I check a private server?
The hosted service checks public addresses. For servers inside your network, self-host OpenUptime there.
TCP 端口监控
不是每个服务都用 HTTP。端口检查会告诉你服务是否在监听，以及建立连接需要多久。
每次检查做什么
- 向 host:port 建立 TCP 连接，并记录耗时。
- 依次尝试这个主机解析出的每个地址，包括 IPv4 和 IPv6。
什么时候告警
- 连接被拒绝，或在超时时间内没有建立。
示例
mail.example.com:25使用说明
- 从多个区域检查，区分是防火墙或路由问题，还是服务真的挂了。
- PostgreSQL、MySQL 和 Redis 请使用数据库监控，它会确认应答的确实是对应的服务。
所有监控通用
- 通过邮件、Slack、Discord、Teams、Telegram、PagerDuty、Webhook、飞书、ntfy 和手机 App 告警。
- 可设置恢复阈值，服务连续多次正常后故障才结束。
- 依赖关系：依赖另一个监控的监控，在被依赖方宕机期间不会告警。
- 维护窗口、故障历史，以及由同一组监控生成的公开状态页。
常见问题
端口能连上就说明服务正常吗？
它只能证明进程在监听，不能证明它能正确应答。如果服务有自己的协议，用能说这个协议的检查会更准确；HTTP 服务请用网站或 API 监控。
能检查内网服务器吗？
托管服务只检查公网地址。内网服务器请在你的网络里自托管 OpenUptime。