final boolean ntlmPost = authorizationHeader.isNtlmType1PostAuthorizationHeader();

        if (ntlmPost) {
            // type 1 NTLM authentication message received
            this.auth.resetSecurityToken(connectionId);
        }

        final byte[] tokenBuffer = authorizationHeader.getTokenBytes();
        this.log.debug("token buffer: {} byte(s)", Integer.valueOf(tokenBuffer.length));

        // log the user in using the token
        IWindowsSecurityContext securityContext;
        try {
            securityContext = this.auth.acceptSecurityToken(connectionId, tokenBuffer, securityPackage);
        } catch (final Win32Exception e) {
            this.log.warn("error logging in user: {}", e.getMessage());
            this.log.trace("", e);
            this.sendUnauthorized(response);
            return false;
        }
        this.log.debug("continue required: {}", Boolean.valueOf(securityContext.isContinue()));

        final byte[] continueTokenBytes = securityContext.getToken();
        if (continueTokenBytes != null && continueTokenBytes.length > 0) {
            final String continueToken = Base64.getEncoder().encodeToString(continueTokenBytes);
            this.log.debug("continue token: {}", continueToken);
            response.addHeader("WWW-Authenticate", securityPackage + " " + continueToken);
        }

        try {
            if (securityContext.isContinue() || ntlmPost) {

this.sendUnauthorized(response);
            return false;
        }

        // create and register the user principal with the session
        final IWindowsIdentity windowsIdentity = securityContext.getIdentity();

        // disable guest login
        if (!this.allowGuestLogin && windowsIdentity.isGuest()) {
            this.log.warn("guest login disabled: {}", windowsIdentity.getFqn());
            this.sendUnauthorized(response);
            return false;
        }

        try {

            this.log.debug("logged in user: {} ({})", windowsIdentity.getFqn(), windowsIdentity.getSidString());

            final GenericPrincipal genericPrincipal = this.createPrincipal(windowsIdentity);

            if (this.log.isDebugEnabled()) {
                this.log.debug("roles: {}", String.join(", ", genericPrincipal.getRoles()));
            }