probelabs/goreplay · error

can't find matching interface

Error message

can't find matching interface

What it means

sock_linux NewSocket walks net.Interfaces() to find the kernel interface matching the pcap.Interface name; no match means the pcap interface list and the kernel's are out of sync (renamed, removed, or unexposed interface), so the socket is not created.

Solutions

1. Confirm the interface name with 'ip link' right before starting gor
2. Handle interfaces that disappear/rename dynamically (re-run discovery)
3. Avoid passing virtual/pcap-only device names that net.Interfaces won't return

When it happens

Trigger: Thrown at internal/capture/sock_linux.go:63 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of probelabs/goreplay@251e45abd2 (2026-09-02). Data as JSON: /api/errors/34d3123afec06dbb. Report an issue: GitHub.

Appendix: source

Thrown at internal/capture/sock_linux.go:63

	loopIndex   int32  // this field must filled to avoid reading packet twice on a loopback device
}

// NewSocket returns new M'maped sock_raw on packet version 2.
func NewSocket(pifi pcap.Interface) (*SockRaw, error) {
	var ifi net.Interface

	infs, _ := net.Interfaces()
	found := false
	for _, i := range infs {
		if i.Name == pifi.Name {
			ifi = i
			found = true
			break
		}
	}

	if !found {
		return nil, fmt.Errorf("can't find matching interface")
	}

	// sock create
	fd, err := unix.Socket(unix.AF_PACKET, unix.SOCK_RAW, int(ETHALL))
	if err != nil {
		return nil, err
	}
	sock := &SockRaw{
		fd:          fd,
		ifindex:     ifi.Index,
		snaplen:     FRAMESIZE,
		pollTimeout: ^uintptr(0),
	}

	// set packet version
	err = unix.SetsockoptInt(fd, unix.SOL_PACKET, unix.PACKET_VERSION, unix.TPACKET_V2)
	if err != nil {
		unix.Close(fd)

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