Exhibit 10.23 AGREEMENT AGREEMENT, dated as of October 20, 1998, by and among NETWORK-1 SECURITY SOLUTIONS, INC. (the "Company"), a Delaware corporation with offices at 70 Walnut Street, Wellesley Hills, Massachusetts 02481 and the noteholders signatory hereto (collectively, the "Noteholders"). WHEREAS, the Underwriter, Whale Securities Co., L.P., has conditioned proceeding with the Company's initial public offering ("IPO") on the Noteholders exchanging outstanding promissory notes in the principal amount plus accrued interest of $2,954,888 (the "Notes") into Series C Preferred Stock, par value $.01 per share, of the Company (the "Preferred Stock"), upon the terms and subject to the conditions set forth herein; WHEREAS, subject to the Company's consummation of its IPO, the Noteholders and the Company desire that the Noteholders exchange the Notes into an aggregate of 562,836 shares of Preferred Stock on the terms and subject to the conditions set forth herein. The Preferred Stock issuable upon exchange of the Notes is referred to herein as the "Preferred Shares." NOW, THEREFORE, for good and valuable consideration, the receipt and sufficiency of which is hereby acknowledged, the parties hereto agree as follows: ARTICLE I. Issuance of Shares for Notes 1.1 Debt Exchange Agreement. Subject to the Company's consummation of the IPO, at the Closing provided for in Section 1.2 hereof, the Company will issue to each Noteholder and, subject to the terms and conditions of this Agreement, each Noteholder will exchange the Notes for the number of Preferred Shares set forth in Exhibit A hereto based on an exchange price of $5.25 per share (the "Debt Exchange"). The form of Certificate of Designation describing the terms of the Preferred Shares is attached as Exhibit B hereto. 1.2 The Closing. The closing of the Debt Exchange (the "Closing") shall take place at the offices of Bizar Martin & Taub, LLP, 1350 Avenue of the Americas, New York, New York, or at such other designated place, simultaneously with the Company's consummation of its IPO (the time and date of the Closing being herein referred to as the "Closing Date"). On the Closing Date there will be issued to the Noteholders the Preferred Shares against delivery and cancellation of the original Notes. The Preferred Shares shall be held in escrow in accordance with Section 1.3 hereof. In the event the Company does not consummate the IPO within ninety (90) days of the date hereof, the terms and provisions of this Agreement shall be null and void and the parties shall have no further obligations to each other pursuant to this Agreement. 1.3 Escrow of Preferred Shares; Over-allotment Option Adjustment. The Preferred Shares to be issued to the Noteholders in accordance with Section 1.1 hereof shall be held in escrow by Bizar Martin & Taub, LLP (the "Escrow Agent") for up to 50 days from the effective date of the IPO. In the event that Whale Securities Co., L.P., exercises its over-allotment option, in whole or in part, to purchase up to an additional 255,000 Preferred Shares of the Company at $6.00 per share (or an aggregate consideration of $1,530,000) (the "Over-allotment Option"), 50% of the net proceeds (after deduction of the Underwriter's commissions and the non-accountable expense allowance) received by the Company from the exercise of the Over-allotment Option shall be used to repay the Notes on a pro-rata basis and the Preferred Shares to be received by the Noteholders in accordance with Section 1.1 hereof shall be proportionately reduced. ARTICLE II. Representations, Warranties, and Agreements of the Company The Company represents and warrants to, and agrees with, the Noteholders as follows: 2.1 Corporate Organization and Qualification. The Company (and its wholly owned subsidiary Network-1 Acquisition Corp.) is a corporation duly organized, validly existing, and in good standing under the laws of its jurisdiction of incorporation, and is qualified to transact business and is in good standing as a foreign corporation in every jurisdiction in which its ownership, leasing, licensing, or use of property or assets or the conduct of its business makes such qualification necessary, except in such jurisdictions where the failure to be so qualified or in good standing would not have a material adverse effect on the business, results of operations, financial condition, or prospects of the Company. Except for Network-1 Acquisition Corp., the Company has no subsidiaries and has no investment, whether by way of ownership of stock or other securities or by loan, advance, or otherwise, in any corporation, partnership, firm, association, or other business entity. The Company has all required power and authority to own its property and to carry on its business as now conducted and proposed to be conducted. 2.2 Validity of Transaction. The Company has all requisite power and authority to execute, deliver, and perform this Agreement, and to issue the Preferred Shares in exchange for the Notes. All necessary corporate proceedings of the Company have been duly taken to authorize the execution, delivery, and performance of this Agreement, and to authorize the issuance of the Preferred Shares for the Notes. This Agreement, has been duly authorized, executed, and delivered by the Company, and constitutes the legal, valid, and binding obligation of the Company, and is enforceable as to the Company in accordance with its respective terms, except as may be limited by applicable bankruptcy, reorganization, insolvency, moratorium, or other similar laws or by legal or equitable principles relating to or limiting creditors' rights generally or as rights to indemnification may be limited by applicable securities laws. Except as to filings which may be required under 2 applicable state securities regulations, no consent, authorization, approval, order, license, certificate, or permit of or from, or declaration or filing with, any Federal, state, local, or other governmental authority or of any court or other tribunal is required by the Company in connection with the transactions contemplated hereby. No consent of any party to any contract, agreement, instrument, lease, license, arrangement, or understanding to which the Company is a party, or by which any of its properties or assets is bound, is required for the execution, delivery, or performance by the Company of this Agreement, and the execution, delivery, and performance of this Agreement, will not violate, result in a breach of, conflict with, or (with or without the giving of notice or the passage of time or both) entitle any party to terminate or call a default under any such contract, agreement, instrument, lease, license, arrangement, or understanding, or violate or result in a breach of any term of the Certificate of Incorporation or By-laws of the Company, or violate, result in a breach of, or conflict with any law, rule, regulation, order, judgment, or decree binding on the Company or to which any of its operations, business, properties, or assets is subject. The Preferred Shares issuable upon exchange of the Notes are duly authorized, will be validly issued, fully paid, and nonassessable, will not have been issued in violation of any preemptive right of stockholders or rights of first refusal, and the Noteholders will have good title to the Preferred Shares, free and clear of all liens, security interests, pledges, charges, encumbrances, stockholders agreements and voting trusts. 2.3 Capitalization. The authorized capital stock of the Company consists of 25,000,000 shares of Common Stock and 5,000,000 shares of preferred stock, par value $.01 per share (the "Preferred Stock"), of which 250,000 Preferred Shares have been designated Series A Redeemable Preferred Stock, 500,000 Preferred Shares have been designated Series B Convertible Preferred Stock and 750,000 shares will be designated Series C Convertible Preferred Stock prior to the Closing Date, having the designations, dividend rights, voting powers, exchange and redemption rights, rights on liquidation or dissolution, and other preferences and relative, participating, optional, or other preferences and relative, participating, optional, or other special rights, and the qualifications, limitations or restrictions thereof, set forth in their respective Certificates of Designations. On the date hereof, the Company has 2,598,464 shares of Common Stock and 500,000 shares of Series B Convertible Preferred Stock outstanding. All issued and outstanding shares of Common Stock and Preferred Stock have been validly issued and are fully paid and nonassessable and have not been issued in violation of any Federal or state securities laws. Except for the obligation of the Company to issue (a) securities referenced in the Amendment No. 1 to the Company's Registration Statement on form SB-2, as filed with the Securities and Exchange Commission on September 16, 1998, relating to the initial public offering of its securities, (b) upon the exercise of the options and warrants which are currently outstanding to purchase 630,886 shares of Common Stock, excluding any options issued or to be issued under the Company's Stock Option Plan), there are not, as of the date hereof, any outstanding or authorized subscriptions, options, warrants, calls, rights, commitments, or any other agreements obligating the Company to issue (i) any additional shares of its capital stock or (ii) any securities convertible into, or exercisable or exchangeable for, or evidencing the right to subscribe for, any shares of its capital stock. Other than the Company's Stock Option Plan, the Company has not adopted or authorized any plan for the benefit of its officers, employees, or directors which require or permit the issuance, sale, purchase, 3 or grant of any shares of the Company's capital stock, any securities convertible into, or exercisable or exchangeable for, or evidencing the right to subscribe for any shares of the Company's capital stock, or any phantom shares or any stock appreciation rights. ARTICLE III. Representations, Warranties, and Agreements of the Noteholders Each of the Noteholders, severally and not jointly, represents and warrants to, and agrees with, the Company as follows: 3.1 Organization. Such Noteholder (if not an individual) is duly organized under the laws of the state of its jurisdiction of organization and has full power and authority to enter into this Agreement and to consummate the transactions set forth herein. All necessary proceedings have been duly taken to authorize the execution, delivery, and performance of this Agreement by such Noteholder (if not an individual). 3.2 Accredited Investor; Access to Information. Each Noteholder and, to the knowledge of such Noteholder, each limited partner or shareholder of such Noteholder in the case of a Noteholder which is a limited partnership or corporation, and each partner of such Noteholder in the case of a Noteholder which is a general partnership, is an "accredited investor," as that term is defined in Rule 501 of Regulation D promulgated under the Securities Act. Each Noteholder, the general partners, limited partners and shareholders of such Noteholder, as the case may be, has had substantial experience in private securities transactions like this one, is capable of evaluating the merits and risks of an investment in the Company, and has had a full opportunity to discuss the business, management, and financial affairs of the Company with the Company's management. Each Noteholder has received all requested documents from the Company and has had a full opportunity to ask questions of, and receive answers from, the officers of the Company. 3.3 Investment Intent. Each Noteholder is acquiring the Preferred Shares for its, his or her own account for investment and not with a view to, or for sale in connection with, any public distribution thereof in violation of the Securities Act. Such Securityholder understands that Preferred Shares have not been registered for sale under the Securities Act or qualified under applicable state securities laws and that the Preferred Shares are being offered and sold to such Noteholder pursuant to one or more exemptions. Such Noteholder understands that it, he or she must bear the economic risk of the investment in the Company for an indefinite period of time, as the Preferred Shares cannot be sold unless subsequently registered under the Securities Act and qualified under state securities laws, unless an exemption from such registration and qualification is available. Such Noteholder acknowledges that no public market for the securities of the Company presently exists and none may develop in the future. 3.4 Transfer of Securities. Such Noteholder will not sell or otherwise dispose of the Preferred Shares unless (a) a registration statement with respect thereto has become effective under 4 the Securities Act and such Preferred Shares have been qualified under applicable state securities laws or (b) there is presented to the Company notice of the proposed transfer and, if it so requests, a legal opinion reasonably satisfactory to the Company that such registration and qualification is not required; provided, however, that no such registration or qualification or opinion of counsel shall be necessary for a transfer by such Noteholder (i) to any entity controlled by, or under common control with, such Noteholder (ii) to a partner or officer of such Noteholder, (iii) to a partner or officer of the general partner of such Noteholder, or (iv) to the spouse, lineal descendants, estate, or a trust for the benefit of any of the foregoing, provided the transferee agrees in writing to be subject to the terms hereof to the same extent as if he were such Noteholder. Such Noteholder consents that any transfer agent of the Company may be instructed not to transfer any Preferred Shares unless it receives satisfactory evidence of compliance with the foregoing provisions, and that there may be endorsed upon any certificate representing such shares (and any certificates issued in substitution therefor) the following legend calling attention to the foregoing restrictions on transferability of such shares, stating in substance: "THE SECURITIES EVIDENCED BY THIS CERTIFICATE HAVE BEEN ACQUIRED FOR INVESTMENT AND HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933 OR QUALIFIED UNDER ANY STATE SECURITIES LAW." The Company shall, upon the request of any holder of a stock certificate bearing the foregoing legend and the surrender of such certificate, issue a new stock certificate without such legend if (A) the stock evidenced by such certificate has been effectively registered under the Securities Act and qualified under any applicable state securities law and sold by the holder thereof in accordance with such registration and qualification, or (B) such holder shall have delivered to the Company a legal opinion reasonably satisfactory to the Company to the effect that the restrictions set forth herein are no longer required or necessary under the Securities Act or any applicable state law. 3.5 Authorization. All actions on the part of such Noteholder necessary for the authorization, execution, delivery, and performance by such Noteholder of this Agreement have been taken. This Agreement has been duly authorized, executed, and delivered by such Noteholder, is the legal, valid, and binding obligation of such Noteholder, and are enforceable as to such Noteholder in accordance with their respective terms, except as may be limited by applicable bankruptcy, reorganization, insolvency, moratorium, or other similar laws or by legal or equitable principles relating to or limiting creditors' rights generally or as rights to indemnification may be limited by applicable securities laws. 3.6 Finder or Broker. Neither such Noteholder nor any person acting on behalf of such Noteholder has negotiated with any finder, broker, intermediary, or similar person in connection with the transactions contemplated herein. 5 ARTICLE IV. Additional Provisions. 4.1 Indemnification. From and after the Closing, the Company, on the one hand, and the Noteholders (severally and not jointly), on the other hand, shall indemnify and save harmless the other (including officer, directors, employees, agents and representatives) against any loss, claim, liability, expense (including reasonable attorney's fees) or other damage caused by or arising out of (i) the breach of any representation or warranty made by any such party or (ii) the failure by the party against whom indemnification is sought to perform any of its covenants or agreements in this Agreement. 4.2 Escrow Agent - Indemnification. The parties acknowledge that: (i) the Escrow Agent is acting solely as a stakeholder at their request and for their convenience and without compensation; (ii) the Escrow Agent shall not be deemed to be the agent of any of the parties; and (iii) the Escrow Agent shall not be liable to any party herein in connection with its role as Escrow Agent, or the performance of its duties as Escrow Agent hereunder, or any act or omission in connection therewith, except for acts of gross negligence or willful misconduct. The parties hereby jointly and severally indemnify and agree to defend and hold the Escrow Agent harmless from and against all costs, claims and expenses, including, but not limited to, reasonable attorneys' fees suffered or incurred by the Escrow Agent and arising out of or related to its role as escrow agent or the performance of its duties hereunder, including the costs and expenses of defending itself (whether by retained attorneys or by itself) against any claim or liability arising out of or related to such role or such performance, except to the extent the same were suffered or incurred as a result of the Escrow Agent's gross negligence or willful misconduct. 4.3 Communications. All notices or other communications hereunder shall be in writing and shall be given by registered or certified mail (postage prepaid and return receipt requested), by an overnight courier service which obtains a receipt to evidence delivery, or by telex or facsimile transmission (provided that written confirmation of receipt is provided), addressed as set forth below: If to the Company: Network-1 Security Solutions, Inc. 70 Walnut Street Wellesley, MA 02481 Attention: Avi A. Fogel, President and Chief Executive Officer With a copy to: Bizar Martin & Taub, LLP 1350 Avenue of the Americas 29th Floor New York, New York 10019 Attention: Sam Schwartz, Esq. 6 If to the Noteholders, at their respective addresses as set forth on Exhibit A hereto, or such other address as any party may designate to the other in accordance with the aforesaid procedure. All notices and other communications sent by overnight courier service shall be deemed to have been given as of the next business day after delivery thereof to such courier service, those given by telex or facsimile transmission shall be deemed given when sent, and all notices and other communications sent by mail shall be deemed given as of the third business day after the date of deposit in the United States mail. 4.4 Successors and Assigns. The Company may not sell, assign, transfer, or otherwise convey any of its rights or delegate any of its duties under this Agreement, except to a corporation which has succeeded to substantially all of the business and assets of the Company and has assumed in writing its obligations under this Agreement, and this Agreement shall be binding on the Company and such successor. This Agreement shall be binding upon, inure to the benefit of, and be enforceable by, the Noteholders and their successors and assigns. 4.5 Amendments and Waivers. Neither this Agreement nor any term hereof may be changed or waived (either generally or in a particular instance and either retroactively or prospectively) absent the written consent each party hereto. 4.6 Survival of Representations. The representations, warranties, covenants, and agreements made herein or in any certificate or document executed in connection herewith shall survive the execution and delivery of this Agreement and the issuance and delivery of the Preferred Shares to the Noteholders. 4.7 Delays or Omissions; Waiver. No delay or omission to exercise any right, power, or remedy accruing to either the Company or the Noteholders upon any breach or default by the other under this Agreement shall impair any such right, power, or remedy no shall it be construed to be a waiver of any such breach or default, or any acquiescence therein or in any similar breach or default thereafter occurring; nor shall any waiver of any single breach or default be deemed a waiver of any other breach or default theretofore or thereafter occurring. 4.8 Entire Agreement; Binding Effect. This Agreement (together with the exhibit attached hereto) contains the entire understanding of the parties with respect to their respective subject matter and all prior negotiations, discussions, commitments, and understandings heretofore had between them with respect thereto are merged herein and therein. This Agreement and the Debt Exchange shall be binding on each Noteholder who executes this Agreement. The failure of any Noteholder named in Exhibit A to execute this Agreement shall not effect the Closing of the Debt Exchange with respect to those Noteholders who have executed this Agreement. 4.9 Headings. All article and section headings herein are inserted for convenience only and shall not modify or affect the construction or interpretation of any provision of this Agreement. 4.10 Counterparts; Governing Law. This Agreement may be executed in any number of counterparts, each of which shall be deemed an original but all of which together shall constitute one and the same instrument. This Agreement shall be governed by, and construed in accordance with, the laws of the State of Massachusetts, without giving effect to conflict of laws. 7 4.11 Further Actions. At any time and from time to time, each party agrees, without further consideration, to take such actions and to execute and deliver such documents as may be reasonably necessary to effectuate the purposes of this Agreement. IN WITNESS WHEREOF, this Agreement has been duly executed on the date hereinabove set forth. NETWORK-1 SECURITY SOLUTIONS, INC. By: /s/ Avi A. Fogel --------------------------------------- Name: Avi A. Fogel Title: President and Chief Executive Officer Noteholders: APPLEWOOD ASSOCIATES, L.P. By: /s/ Barry Rubenstein --------------------------------------- Name: Barry Rubenstein Title: General Partner CMH CAPITAL MANAGEMENT CORP. By: /s/ Corey M. Horowitz --------------------------------------- Name: Corey M. Horowitz Title: President /s/ Corey M. Horowitz --------------------------------------- COREY M. HOROWITZ RAPTUR MANAGEMENT CO. By: /s/ Steve Ackerman --------------------------------------- Name: Title: /s/ Douglas Lipton --------------------------------------- DOUGLAS LIPTON 8 /s/ Lawrence A. Wein --------------------------------------- LAWRENCE WEIN /s/ Steven Heineman --------------------------------------- STEVEN HEINEMAN /s/ Herb Karlitz --------------------------------------- HERB KARLITZ /s/ Charles Stevenson --------------------------------------- CHARLES P. STEVENSON, JR. /s/ Albert Kalimian --------------------------------------- ALBERT KALIMIAN NAVIGATOR FUND, L.P By: /s/ Corey Horowitz --------------------------------------- Name: Corey M. Horowitz Title: Authorized Signatory NAVIGATOR GLOBAL FUND By: /s/ Corey Horowitz --------------------------------------- Name: Corey M. Horowitz Title: Authorized Signatory /s/ Robert Graifman --------------------------------------- ROBERT GRAIFMAN MBF CAPITAL CORP. By: /s/ Mark Fisher --------------------------------------- Name: Title: 9 EXHIBIT A