EXHIBIT 10.1
                                                                    ------------

                       NETWORK-1 SECURITY SOLUTIONS, INC.
                           445 PARK AVENUE, SUITE 1028
                              NEW YORK, N.Y. 10022





                                December 20, 2006



Mr. David Kahn
380 Hempstead Avenue, Suite 5
West Hempstead, New York  10017

Dear David:

     On behalf of Network-1 Security Solutions, Inc. (the "Company"), this
letter summarizes the terms upon which the Company will continue to retain your
services as Chief Financial Officer of the Company.

     The Company has agreed to use your services through the year ending
December 31, 2008. In consideration thereof, you shall receive the following
compensation (the "Compensation"):

          (i) $6615 per month from January 1, 2007 through December 31, 2007;
     and

          (ii) $6945 per month from January 1, 2008 through December 31,
     2008.

            Subject to your execution of this letter agreement, the Company's
Board of Directors has approved the issuance to you of options (the "Option") to
purchase 75,000 shares of common stock, at an exercise price of $1.50 per share
(equal the fair market value of the Company's Common Stock on the date of
grant). The Option shall vest as follows: 30,000 shares underlying the Option
shall vest immediately and the balance of 45,000 shares shall vest on a
quarterly basis in equal amounts of 5,625 beginning March 31, 2007 through
December 31, 2008. Notwithstanding the foregoing, upon a Change in Control of
the Company (as defined below) all of the unvested shares underlying the Option
shall become immediately exercisable and shall become one-hundred percent (100%)
vested.
<PAGE>

     For purposes of this letter agreement, a "Change in Control" shall mean,
with respect to the Company, the occurrence of any of the following events:

     (i) the shareholders of the Company approve a merger or consolidation of
the Company with any other entity, other than a merger or consolidation which
would result in the voting securities of the Company outstanding immediately
prior thereto continuing to represent more than fifty pecent (50%) of the total
voting power represented by the voting securities of the Company or such
surviving entity outstanding immediately after such merger or consolidation,
(ii) the shareholders of the Company approve a plan of complete liquidation of
the Company, (iii) the Company consummates the sale or disposition of all or
substantially all of its assets (other than to a subsidiary or subsidiaries) or
(iv) any other event deemed to constitute a "Change of Control" by the Board of
Directors of the Company.

     As Chief Financial Officer of the Company you will continue to be
responsible, among other things, for the maintenance of the books and records of
the Company, the preparation of tax returns and financial statements for the
Board of Directors of the Company and for required financial filings with the
Securities and Exchange Commission including certifications required to be
signed by you as Chief Financial Officer.

     You understand that your relationship with the Company will continue to be
as an independent contractor and not as an employee. The Company may terminate
this letter agreement and your services at any time for any reason. However, in
the event your employment is terminated without "Good Cause" (as defined below),
you shall be entitled to receive the accelerated vesting of all remaining
unvested shares underlying the Option and the lesser of (i) six months month's
Compensation or (ii) the remaining balance of the Compensation payable to you
through December 31, 2008. A termination for "Good Cause" shall be defined as
follows: (i) commission of an act constituting a felony or involving fraud,
moral terpitude, theft or dishonesty which is not a felony and which materially
adversely affects the Company or could reasonably be expected to materially
adversely affect the Company, (ii) failure to perform your duties as Chief
Financial Officer which, if curable, shall not have been cured with 10 days
written notice from the Company, (iii) failure to follow the lawful directions
of the Board of Directors of the Company, which, if curable, shall not have been
cured within 10 days written notice from the Company, or (iv) your material
breach of the terms of this letter agreement.
<PAGE>

     It is a great pleasure to have you continue to serve Network-1 Security
Solutions, Inc. I fully expect that you will continue to make a major
contribution to the Company's success. Kindly execute below to confirm your
agreement to the terms set forth herein.

                                      Sincerely,



                                      Corey M. Horowitz,
                                      Chairman and CEO



Agreed and Accepted:

-----------------------------
David C. Kahn, CPA



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Dated:  December 20, 2006