fatedier/frp · error

bind port is required

Error message

bind port is required

What it means

Validation error from validateVisitorBaseConfig: a visitor entry has bindPort set to 0 (the Go zero value for an unset port). The visitor listens locally on bindAddr:bindPort to expose the remote service, so an explicit non-zero local port is mandatory. Third check in visitor base validation.

Source

Thrown at pkg/config/v1/validation/visitor.go:52

	case *v1.XTCPVisitorConfig:
		return validateXTCPVisitorConfig(v)
	default:
		return errors.New("unknown visitor config type")
	}
	return nil
}

func validateVisitorBaseConfig(c *v1.VisitorBaseConfig) error {
	if c.Name == "" {
		return errors.New("name is required")
	}

	if c.ServerName == "" {
		return errors.New("server name is required")
	}

	if c.BindPort == 0 {
		return errors.New("bind port is required")
	}
	return nil
}

func validateXTCPVisitorConfig(c *v1.XTCPVisitorConfig) error {
	if !slices.Contains([]string{"kcp", "quic"}, c.Protocol) {
		return fmt.Errorf("protocol should be kcp or quic")
	}
	return nil
}

View on GitHub (pinned to 6c8a8d0a97)

Solutions

1. Add bindPort = 9000 (a free local TCP port) to the visitor entry.
2. Also set bindAddr = "127.0.0.1" if you want the visitor loopback-only (bindAddr itself is optional with a default).
3. Check the port is not already in use on the machine running frpc.

Example fix

# before
[[visitors]]
name = "v"
type = "stcp"
serverName = "stcp-srv"
secretKey = "s"
bindAddr = "127.0.0.1"

# after
[[visitors]]
name = "v"
type = "stcp"
serverName = "stcp-srv"
secretKey = "s"
bindAddr = "127.0.0.1"
bindPort = 9000

base := v.GetBaseConfig()
if base == nil || base.BindPort == 0 {
    return errors.New("visitor requires an explicit non-zero bindPort")
}

func visitorBindPortSet(c v1.VisitorConfigurer) bool {
    base := c.GetBaseConfig()
    return c != nil && base != nil && base.BindPort != 0
}

if err := validation.ValidateVisitorConfigurer(v); err != nil {
    if strings.Contains(err.Error(), "bind port is required") {
        // choose a free local port and set bindPort
    }
    return err
}

When it happens

Trigger: A [[visitors]] entry with bindPort omitted or set to 0. Note 0 is treated as 'missing', so a genuine desire to use port 0 (random port) is rejected — frp requires a concrete port.

Common situations: Copying a proxy block (which uses remotePort) and forgetting visitors need bindPort; assuming frpc picks a free port automatically; TOML key typo BindPort/bindport; programmatic configs leaving VisitorBaseConfig.BindPort unset.

Related errors

• name is required
• server name is required
• type shouldn't be empty
• type [%s] error
• visitor plugin type is empty

AI-assisted analysis of fatedier/frp@6c8a8d0a97 (2026-08-15). Data as JSON: /api/errors/0160a3ab7dfb4ffb. Report an issue: GitHub.