Exhibit 10.6 June 30, 1998 Avi A. Fogel, President and Chief Executive Officer Network-1 Security Solutions, Inc. 909 Third Avenue - 9th Floor New York, New York 10022 Dear Avi: This letter shall confirm that each of the undersigned agree that the provision in paragraph 3 of our respective employment agreements, dated April 4, 1994, and as amended on February 16, 1996, with Network-1, providing for a 10% increase in salary was waived by us at the time we were eligible for such 10% increases due to the financial circumstances of Network-1 and we will make no claim for such 10% increase at any time in the future. Very truly yours, /s/ Robert Russo ------------------------------ Robert Russo /s/ William Hancock ------------------------------ William Hancock N/A ------------------------------ Kenneth Conquest AGREED AND ACCEPTED: Network-1 Security Solutions, Inc. By /s/ Avi A. Fogel --------------------------------------- Avi A. Fogel, President and and Chief Executive Officer