public byte[] getChallenge(final CIFSContext tf, final Address dc, final int port) throws SmbException {
        try (SmbTransportInternal trans = tf.getTransportPool()
                .getSmbTransport(tf, dc, port, false, !tf.getCredentials().isAnonymous() && tf.getConfig().isIpcSigningEnforced())
                .unwrap(SmbTransportInternal.class)) {
            trans.ensureConnected();
            return trans.getServerEncryptionKey();

     *
     * @see jcifs.smb.SmbResourceLocatorInternal#shouldForceSigning()
     */
    @Override
    public boolean shouldForceSigning() {
        return this.ctx.getConfig().isIpcSigningEnforced() && !this.ctx.getCredentials().isAnonymous() && isIPC();
    }

    /**
     * {@inheritDoc}
     *
     * @see jcifs.SmbResourceLocator#isIPC()
     */
    @Override
    public boolean isIPC() {

                }
                return ssn.acquire();
            }
            if (log.isTraceEnabled()) {
                log.trace("Existing session " + ssn + " does not match " + tf.getCredentials());
            }
        }

        /* logoff old sessions */
        if (tf.getConfig().getSessionTimeout() > 0 && this.sessionExpiration < (now = System.currentTimeMillis())) {