synchronized (session.transport()) {
            if (response != null) {
                response.received = false;
            }
            treeConnect(request, response);
            if (request == null || response != null && response.received) {
                return;
            }
            if (!service.equals("A:")) {
                switch (request.command) {

                          Skipping DC interrogation.""");
            }
        } else {
            final SmbSession ssn = trans.getSmbSession(NtlmPasswordAuthentication.DEFAULT);
            ssn.getSmbTree(LOGON_SHARE, null).treeConnect(null, null);
        }
        return new NtlmChallenge(trans.server.encryptionKey, dc);
    }

    /**
     * Retrieves an NTLM challenge from a domain controller for the configured domain.
     *

            T chainedResponse = null;
            if (!(request instanceof SmbComTreeDisconnect) && !(request instanceof Smb2TreeDisconnectRequest)) {
                chainedResponse = treeConnect(request, response);
            }
            if (request == null || chainedResponse != null && chainedResponse.isReceived()) {
                return chainedResponse;
            }

            t.markDomainDfs();
        }

        try {
            if (log.isTraceEnabled()) {
                log.trace("doConnect: " + addr);
            }
            t.treeConnect(null, null);
            return t.acquire();
        } catch (final SmbAuthException sae) {
            log.debug("Authentication failed", sae);
            return retryAuthentication(loc, share, trans, t, referral, sae);

        if (logonShare == null || logonShare.isEmpty()) {
            throw new SmbException("Logon share is not defined");
        }
        try (SmbTreeImpl t = getSmbTree(logonShare, null)) {
            t.treeConnect(null, null);
        } catch (CIFSException e) {
            throw SmbException.wrap(e);
        }
    }

    boolean isSignatureSetupRequired() throws SmbException {

            tree.connectionState = 2;
        }

        try {
            if (LogStream.level >= 3) {
                log.println("doConnect: " + addr);
            }

            tree.treeConnect(null, null);
        } catch (final SmbAuthException sae) {
            NtlmPasswordAuthentication a;
            SmbSession ssn;

            if (share == null) { // IPC$ - try "anonymous" credentials