shadow1ng/fscan · error

smbv2_negotiate_send_failed: %w

Error message

smbv2_negotiate_send_failed: %w

What it means

Guard in probeSMBv2: writing the SMBv2 negotiate packet to the secondary TCP connection failed. The dial succeeded but the write errored, so SMBv2 protocol/dialect negotiation never starts.

Source

Thrown at plugins/services/smb_protocol.go:304

	}

	return info, nil
}

// probeSMBv2 处理SMBv2协议信息收集
func probeSMBv2(ctx context.Context, target string, timeout time.Duration, session *common.ScanSession) (*SMBTarget, error) {
	conn2, err := session.DialTCP(ctx, "tcp", target, timeout)
	if err != nil {
		return nil, fmt.Errorf(i18n.Tr("service_connection_failed", "%w"), err)
	}
	defer func() { _ = conn2.Close() }()

	_ = conn2.SetDeadline(time.Now().Add(timeout))

	// 发送SMBv2协商包
	_, err = conn2.Write(smbv2NegotiatePacket)
	if err != nil {
		return nil, fmt.Errorf("%s: %w", i18n.GetText("smbv2_negotiate_send_failed"), err)
	}

	r2, err := readSMBMessage(conn2)
	if err != nil {
		return nil, fmt.Errorf("%s: %w", i18n.GetText("smbv2_negotiate_read_failed"), err)
	}

	// 构建NTLM数据包
	var ntlmData []byte
	if len(r2) > 70 && hex.EncodeToString(r2[70:71]) == "03" {
		flags := []byte{0x15, 0x82, 0x08, 0xa0}
		ntlmData = buildNTLMSSPData(flags)
	} else {
		flags := []byte{0x05, 0x80, 0x08, 0xa0}
		ntlmData = buildNTLMSSPData(flags)
	}

	// 发送Session Setup

View on GitHub (pinned to 95cc12e753)

Solutions

1. Retry the SMBv2 probe on a fresh connection
2. Increase the deadline
3. Check for middleboxes interfering with SMB traffic

When it happens

Trigger: Thrown at plugins/services/smb_protocol.go:304 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of shadow1ng/fscan@95cc12e753 (2026-09-06). Data as JSON: /api/errors/153daaa03ba6eb32. Report an issue: GitHub.