shadow1ng/fscan · error

smbv2_ntlm_send_failed

Error message

smbv2_ntlm_send_failed: %w

What it means

Guard in probeSMBv2: writing the constructed NTLMSSP NEGOTIATE packet failed after session setup completed. The NTLM negotiation that yields server version info cannot be sent, aborting the fingerprint attempt.

Solutions

1. Retry the NTLM exchange on a new connection
2. Increase the deadline
3. Verify no security device is resetting NTLM traffic

When it happens

Trigger: Thrown at plugins/services/smb_protocol.go:336 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/95c0708c145e2ec0. Report an issue: GitHub.

Appendix: source

Thrown at plugins/services/smb_protocol.go:336

		flags := []byte{0x05, 0x80, 0x08, 0xa0}
		ntlmData = buildNTLMSSPData(flags)
	}

	// 发送Session Setup
	_, err = conn2.Write(smbv2SessionSetupPacket)
	if err != nil {
		return nil, fmt.Errorf("%s: %w", i18n.GetText("smbv2_session_send_failed"), err)
	}

	_, err = readSMBMessage(conn2)
	if err != nil {
		return nil, fmt.Errorf("%s: %w", i18n.GetText("smbv2_session_read_failed"), err)
	}

	// 发送NTLM协商包
	_, err = conn2.Write(ntlmData)
	if err != nil {
		return nil, fmt.Errorf("%s: %w", i18n.GetText("smbv2_ntlm_send_failed"), err)
	}

	ret, err := readSMBMessage(conn2)
	if err != nil {
		return nil, fmt.Errorf("%s: %w", i18n.GetText("smbv2_ntlm_read_failed"), err)
	}

	ntlmOff := bytes.Index(ret, []byte("NTLMSSP"))
	if ntlmOff == -1 {
		return &SMBTarget{Protocol: SMBProtocol2}, nil
	}

	info := &SMBTarget{
		Protocol: SMBProtocol2,
	}

	parseNTLMChallenge(ret[ntlmOff:], info)
	return info, nil

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