SC 13D

	UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
	Washington, D.C. 20549
	SCHEDULE 13D

Under the Securities Exchange Act of 1934
(Amendment No.  )*

CoSine Communications, Inc.

(Name of Issuer)

Common Stock

(Title of Class of Securities)

221222607

(CUSIP Number)

Randall K. Gausman

Tut Systems, Inc.

600 SW Meadows Rd., Suite 200

Lake Oswego, OR 97035

(971) 217-0400

(Name, Address and Telephone Number of Person
Authorized to Receive Notices and Communications)

February 17, 2005

(Date of Event which Requires Filing of this Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box. o

Note: Schedules filed in paper format shall include a signed original and five copies of the schedule, including all exhibits. See §240.13d-7 for other parties to whom copies are to be sent.

^* The remainder of this cover page shall be filled out for a reporting person’s initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter disclosures provided in a prior cover page.

The information required on the remainder of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934 (“Act”) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

CUSIP No.  221222607
	1.	Names of Reporting Persons. I.R.S. Identification Nos. of above persons (entities only) Tut Systems, Inc. 94-2958543
	2.	Check the Appropriate Box if a Member of a Group (See Instructions)
		(a)			o
		(b)			o
	3.	SEC Use Only
	4.	Source of Funds (See Instructions) OO
	5.	Check if Disclosure of Legal Proceedings Is Required Pursuant to Items 2(d) or 2(e)  o
	6.	Citizenship or Place of Organization Delaware
Number of Shares Beneficially Owned by Each Reporting Person With			7.	Sole Voting Power 1,122,063
			8.	Shared Voting Power  0
			9.	Sole Dispositive Power  0
			10.	Shared Dispositive Power  0
	11.	Aggregate Amount Beneficially Owned by Each Reporting Person  1,122,063
	12.	Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions)   o
	13.	Percent of Class Represented by Amount in Row (11)  11%
	14.	Type of Reporting Person (See Instructions) CO

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Item 1.	Security and Issuer
This Schedule relates to shares of Common Stock (“Issuer Common Stock”) of CoSine Communications, Inc. (“Issuer”).  CoSine’s principal executive offices are located at CoSine Communications, Inc., 560 S. Winchester Blvd., Suite 500, San Jose, California 95128
Item 2.	Identity and Background
This Schedule is being filed by Tut Systems, Inc. (“Tut Systems”), a Delaware Corporation.  The principal business address of Tut Systems, Inc., is 600 SW Meadows Rd. Suite 200, Lake Oswego, OR 97035.  Tut Systems designs, develops, and sells digital video processing systems that enable telephony-based service providers to deliver broadcast quality digital video signals over their networks.
(d)           During the last five years, Tut Systems has not been convicted in a criminal proceeding.
(e)           During the last five years, Tut Sytems has not been a party to a civil proceeding of a judicial or administrative body of competent jurisdiction that resulted in a judgment, decree or final order enjoining future violations of, or prohibiting or mandating activities subject to, federal or state securities laws or finding any violation with respect to such laws.
Item 3.	Source and Amount of Funds or Other Consideration
Pursuant to an Agreement and Plan of Merger, dated as of January 7, 2005 (the “Merger Agreement”), by and among Tut Systems, Cadillac Merger Sub, a Delaware corporation and wholly owned subsidiary of Tut Systems (“Merger Sub”), and the Issuer, and subject to the conditions set forth therein, the Issuer will be merged with and into Merger Sub (the “Merger”), with each share of Issuer Common Stock being converted into the right to receive a to-be-determined number of shares of common stock of Tut Systems, par value $.0001 per share (“Tut Systems Common Stock”). The Merger is subject to the approval of the Merger Agreement by the stockholders of Issuer and the approval by the stockholders of Tut Systems of the issuance of the Tut Systems Common Stock in connection with the Merger.  The foregoing summary of the Merger Agreement is qualified by reference to the copy of the form of the Voting Agreement included as Exhibit 1 to this Schedule 13D and incorporated herein in its entirety by reference.
Item 4.	Purpose of Transaction
(a) – (b) As described in Item 3 above, this Schedule 13D relates to the Merger of the Issuer with and into Merger Sub in a statutory merger pursuant to the Delaware General Corporation Law. At the effective time of the Merger, the separate existence of the Issuer will cease and the Merger Sub will continue as the surviving corporation and as a wholly owned subsidiary of Tut Systems (the “Surviving Corporation”). Holders of outstanding Issuer Common Stock will receive, in exchange for each share of Issuer Common Stock held by them immediately prior to the Merger, a to-be-determined number of shares of Tut Systems Common Stock.
As an inducement for Tut Systems to enter into the Merger Agreement, certain stockholders of the issuer (collectively, the “Voting Agreement Stockholders”) have entered into Voting Agreement, dated as of January 7, 2005 (the “Voting Agreement”), with Tut Systems and have, by executing the Voting Agreement, irrevocably appointed Tut Systems (or any nominee of Tut Systems) as his, her or its lawful attorney and proxy. Such proxy gives Tut Systems the limited right to vote each of the 1,122,063 shares of Issuer Common Stock beneficially owned (collectively, the “Shares”), including options, by the Voting Agreement Stockholders in all matters related to the Merger.  The Voting Agreement Stockholders and the number of Shares beneficially owned by each of them are set forth in Schedule A hereto which is hereby incorporated by reference. The foregoing summary of the Voting Agreement is qualified by reference to the copy of the form of the Voting Agreement included as Exhibit 2 to this Schedule 13D and incorporated herein in its entirety by reference.
In exercising its right to vote the Shares as lawful attorney and proxy of the Voting Agreement Stockholders, Tut Systems (or any nominee of Tut Systems) will be limited, at every Issuer stockholders’ meeting called with respect to any of the following, and at every adjournment or postponement thereof, and on every action or approval by written consent of the stockholders of the Company with respect to any of the following:  (a) in favor of adoption of the Merger Agreement and approval of the Merger, (b) against any proposal for any Acquisition Transaction (as defined in the Merger Agreement), other than the Merger, between the Company and any Person or entity other than Parent and (c) against any other action or agreement that would result in a breach of any covenant, representation or warranty or any other obligation or agreement of the Company under the Merger Agreement or which could result in any of the conditions to the consummation of the Merger under the Merger Agreement not being fulfilled. The Voting Agreement Stockholders may vote the Shares on all other matters. The Voting Agreement terminates upon the earlier to occur of (i) such date and time as the Merger shall become effective in accordance with the terms and provisions of the Merger Agreement and (ii) the date of termination of the Merger Agreement.
(c)           Not applicable.
(d)           Upon consummation of the Merger, the directors of Merger Sub shall be the directors of Merger Sub, until their respective successors are duly elected or appointed and qualified. The officers of Merger Sub shall be the officers of Merger Sub, until their respective successors are duly elected or appointed and qualified.
(e)           Other than as a result of the Merger described in Item 3 above, not applicable.
(f)            Not applicable.
(g)           Upon consummation of the Merger, the Certificate of Incorporation of the Surviving Corporation shall e amended in its entirety to read as set forth in Exhibit E to the Merger Agreement until thereafter amended as provided by the Delaware General Corporations Law (the “DGCL”) and such Certificate of Incorporation.  Upon consummation of the Merger, the Bylaws of Merger Sub, as in effect immediately prior to the Merger, shall be the Bylaws of the Surviving Corporation until thereafter amended, in accordance with the DGCL, the Certificate of Incorporation and such Bylaws.
(h) – (i) If the Merger is consummated as planned, all shares of the Issuer Common Stock will be deregistered under the Securities and Exchange Act of 1934 and delisted from the Nasdaq Stock Market.
(j)            Other than as described above, Tut Systems currently has no plan or proposals that relate to, or would result in, any of the matters required to be disclosed in response to paragraphs (a) through (j), inclusive of Item 4 of Schedule 13D (although Tut Systems reserves the right to develop such plans).

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Item 5.	Interest in Securities of the Issuer
(a) – (b) As a result of the Voting Agreement, Tut Systems may be deemed to be the beneficial owner of at least 1,122,063 shares of Issuer Common Stock. Such Issuer Common Stock constitutes, based on the number of shares outstanding on February 8, 2005 as represented by the Issuer in the Merger Agreement together with the shares underlying options reported in this Schedule 13D, approximately 11% of the issued and outstanding shares of Issuer Common Stock.
Tut Systems has sole power to vote all of the Shares for the limited purposes described above in connection with the Voting Agreement.  However, Tut Systems disclaims any beneficial ownership of the shares of Issuer common stock which are covered by the Voting Agreement.  Tut Systems does not have the sole power to vote or to direct the vote or to dispose or to direct the disposition of any shares of Issuer Common Stock other than pursuant to the Voting Agreement  and Tut Systems is not entitled to any rights as a stockholder of Issuer as to the Shares covered by the Voting Agreement. To the best of Tut Systems’ knowledge, no shares of Issuer Common Stock are beneficially owned by any of the Offiers and Directors of Tut Systems named in Schedule B.
(c)           Neither Tut Systems nor, to the knowledge of Tut Systems, any person named in Schedule B, has effected any transaction in the Issuer Common Stock during the past 60 days.
(d)           To Tut Systems’ knowledge, no other person than each record owner of Issuer common stock has the right to receive or the power to direct the receipt of dividends from or the proceeds of the sale of such shares of Issuer common stock.
(e)           Not applicable.
Item 6.	Contracts, Arrangements, Understandings or Relationships with Respect to Securities of the Issuer
Other than the Merger Agreement and the Voting Agreement, to the knowledge of Tut Systems, there are no contracts, arrangements, understandings or relationships (legal or otherwise) among the persons named in Item 2 and between such persons and any person with respect to any securities of the Issuer, including but not limited to transfer or voting of any of the securities, finder’s fees, joint ventures, loan or option arrangements, puts or calls, guarantees of profits, division of profits or loss, or the giving or withholding of proxies.
Item 7.	Material to Be Filed as Exhibits

EXHIBIT NO.	DESCRIPTION
Exhibit 1*	Agreement and Plan of Merger, dated as of January 7, 2005 by and among Tut Systems, Inc., Cadillac Merger Sub and CoSine Communications.
Exhibit 2	Form of Voting Agreement by and between Tut Systems, Inc. and certain stockholders of CoSine Communications, Inc.

*      Incorporated by reference to Exhibit 2.1 to Tut Systems, Inc.’s Current Report on Form 8-K filed on January 10, 2005.

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SCHEDULE A

The following table sets forth the names, shares beneficially owned and the percentage of ownership of those CoSine Communications, Inc. stockholders who entered into a Voting Agreement with Tut Systems, Inc.

	Shares Beneficially Owned
Name	Number	Percent
Crescendo Ventures	890,244	8.7	%
Stephen Goggiano	146,248	1.4	%
Terry Gibson	40,083		*
Donald Green	32,063		*
Charles J. Abbe	9,950		*
R. David Spreng	3,475		*

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SCHEDULE B

The following table sets forth the names, addresses and principal occupations of the directors and executive officers of Tut Systems, Inc. (“Tut Systems”). The principal business address of each such director and executive officer is the address of Tut Systems, 6000 SW Meadows Rd. Suite 200, Lake Oswego, OR 97035. Each of such directors and executive officers is a citizen of the United States.

Name	Position
Salvatore D’Auria	Chairman of the Board, President and Chief Executive Officer
Craig Bender	Vice President of Marketing and Corporate Development
Mark Carpenter	Vice President of Partner Development
Randall Gausman	Vice President, Finance and Administration, Chief Financial Officer and Secretary
Robert Noonan	Vice President, Global Sales
Charles Van Dusen	Vice President, Chief Technical Officer
Neal Douglas	Director
Clifford Higgerson	Director
George Middlemas	Director
Roger Moore	Director

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After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Date: February 17, 2005
	TUT SYSTEMS, INC., a Delaware corporation
	By:	/s/ Randall K. Gausman
		Name:	Randall K. Gausman
		Title:	Chief Financial Officer

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EX-2

Exhibit 2

FORM OF VOTING AGREEMENT FOR TUT SYSTEMS

VOTING AGREEMENT

        This Voting Agreement ("Agreement") is made and entered into as of January 7, 2005, by and between TUT Systems, Inc., a Delaware corporation ("Parent"), and the undersigned stockholder ("Stockholder") of Cosine Communications, Inc., a Delaware corporation (the "Company"). Certain capitalized terms used in this Agreement that are not defined herein or in Section 8 shall have the meaning given to such terms in the Merger Agreement (as defined below).

RECITALS

        WHEREAS, Stockholder is the holder of record and the "beneficial owner" (within the meaning of Rule 13d-3 under the Securities Exchange Act of 1934) of certain shares of common stock of the Company;

        WHEREAS, concurrently with the execution and delivery of this Agreement, Parent, Cadillac Merger Corporation, a Delaware corporation and wholly owned subsidiary of Parent ("Merger Sub") and the Company are entering into an Agreement and Plan of Merger and Reorganization (the "Merger Agreement") which provides, upon the terms and subject to the conditions set forth therein, for the merger of Merger Sub with and into the Company (the "Merger"); and

        WHEREAS, as a condition and inducement to Parent's willingness to enter into the Merger Agreement, Stockholder has agreed to execute and deliver this Agreement.

        NOW, THEREFORE, the parties to this Agreement, intending to be legally bound, agree as follows:

        1.    Agreement to Vote Shares.    Prior to the Termination Date, at every meeting of the stockholders of the Company called with respect to any of the following, and at every adjournment or postponement thereof, and on every action or approval by written consent of the stockholders of the Company with respect to any of the following, Stockholder shall vote the Subject Securities: (a) in favor of adoption of the Merger Agreement and approval of the Merger, (b) against any proposal for any Acquisition Transaction (as defined in the Merger Agreement), other than the Merger, between the Company and any Person or entity other than Parent and (c) against any other action or agreement that would result in a breach of any covenant, representation or warranty or any other obligation or agreement of the Company under the Merger Agreement or which could result in any of the conditions to the consummation of the Merger under the Merger Agreement not being fulfilled.

        2.    Irrevocable Proxy.    Concurrently with the execution of this Agreement, Stockholder agrees to deliver to Parent a proxy in the form attached hereto (the "Proxy"), which shall be irrevocable to the extent provided in Section 212 of the Delaware General Corporation Law, with respect to the shares referred to therein.

        3.    Agreement to Retain Shares.    

        (a)   Restriction on Transfer. Except as otherwise provided in Section 3(c), during the period from the date of this Agreement through the Termination Date, Stockholder shall not, directly or indirectly, cause or permit any Transfer of any of the Subject Securities to be effected.

        (b)   Restriction on Transfer of Voting Rights. During the period from the date of this Agreement through the Termination Date, Stockholder shall ensure that: (a) none of the Subject Securities is deposited into a voting trust; and (b) no proxy (other than the Proxy granted herein) is granted, and no voting agreement or similar agreement is entered into, with respect to any of the Subject Securities.

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        (c)   Permitted Transfers. Section 3(a) shall not prohibit a transfer of Company Common Stock by Stockholder (i) upon the death of Stockholder, or (ii) if Stockholder is a partnership or limited liability company, to one or more partners or members of Stockholder or to an affiliated corporation under common control with Stockholder; provided, however, that a transfer referred to in this sentence shall be permitted only if, as a precondition to such transfer, the transferee agrees in a writing, reasonably satisfactory in form and substance to Parent, to be bound by the terms of this Agreement and delivers a Proxy to Parent in substantially the form of the Proxy attached hereto.

        4.    Waiver of Appraisal Rights.    Stockholder hereby irrevocably and unconditionally waives any rights of appraisal, any dissenters' rights and any similar rights relating to the Merger or any related transaction that Stockholder may have by virtue of any outstanding shares of Company Common Stock Owned by Stockholder.

        5.    Representations, Warranties and Covenants of Stockholder.    Stockholder hereby represents and warrants to Parent as follows:

        (a)   Due Authorization, Etc. All consents, approvals, authorizations and orders necessary for the execution and delivery by Stockholder of this Agreement and the Proxy have been obtained, and Stockholder has full right, power and authority to enter into this Agreement and the Proxy. This Agreement and the Proxy have been duly executed and delivered by Stockholder and constitute valid and binding agreements of Stockholder enforceable in accordance with their terms, except as the same may be limited by bankruptcy, insolvency, reorganization, moratorium or similar laws now or hereafter in effect relating to creditors' rights generally and subject to general principles of equity.

        (b)   No Conflict. The execution and delivery of this Agreement and the Proxy by Stockholder do not, and the performance of this Agreement and the Proxy by Stockholder will not (i) conflict with or violate any law, rule, regulation, order, decree or judgment applicable to Stockholder or by which he or it or any of his or its properties is or may be bound or affected; or (ii) result in or constitute any breach of or default under, or give to any other Person any right of termination, amendment, acceleration or cancellation of, or result in the creation of any encumbrance or restriction on any of the Subject Securities pursuant to, any contract to which Stockholder is a party or by which Stockholder or any of his or its affiliates or properties is or may be bound or affected.

        (c)   Title to Securities. As of the date of this Agreement: (a) Stockholder holds of record (free and clear of any encumbrances or restrictions) the number of outstanding shares of Company Common Stock set forth under the heading "Shares Held of Record" on the signature page hereof; (b) Stockholder holds (free and clear of any encumbrances or restrictions) the options, warrants and other rights to acquire shares of Company Common Stock set forth under the heading "Options and Other Rights" on the signature page hereof; (c) Stockholder Owns the additional securities of the Company set forth under the heading "Additional Securities Beneficially Owned" on the signature page hereof; and (d) Stockholder does not directly or indirectly Own any shares of capital stock or other securities of the Company, or any option, warrant or other right to acquire (by purchase, conversion or otherwise) any shares of capital stock or other securities of the Company, other than the shares and options, warrants and other rights set forth on the signature page hereof.

        (d)   Accuracy of Representations. The representations and warranties contained in this Agreement are accurate in all respects as of the date of this Agreement, and will be accurate in all respects at all times through the Termination Date.

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        6.    Additional Covenants of Stockholder.    

        (a)   Further Assurances. From time to time and without additional consideration, Stockholder shall (at Stockholder's sole expense) execute and deliver, or cause to be executed and delivered, such additional transfers, assignments, endorsements, proxies, consents and other instruments, and shall (at Stockholder's sole expense) take such further actions, as Parent may request for the purpose of carrying out and furthering the intent of this Agreement.

        7.    Miscellaneous.    

        (a)   Survival of Representations, Warranties and Agreements. All representations and warranties made by Stockholder in this Agreement shall survive (i) the consummation of the Merger, and (ii) the Termination Date.

        (b)   Assignment; Binding Effect. Except as provided herein, neither this Agreement nor any of the interests or obligations hereunder may be assigned or delegated by Stockholder, and any attempted or purported assignment or delegation of any of such interests or obligations shall be void. Subject to the preceding sentence, this Agreement shall be binding upon Stockholder and his heirs, estate, executors and personal representatives and his or its successors and assigns, and shall inure to the benefit of Parent and its successors and assigns. Without limiting any of the restrictions set forth in Section 3(a) or elsewhere in this Agreement, this Agreement shall be binding upon any Person to whom any Subject Securities are transferred. Nothing in this Agreement is intended to confer on any Person (other than Parent and its successors and assigns) any rights or remedies of any nature.

        (c)   Specific Performance. The parties agree that irreparable damage would occur in the event that any of the provisions of this Agreement or the Proxy were not performed in accordance with its specific terms or were otherwise breached. Stockholder agrees that, in the event of any breach or threatened breach by Stockholder of any covenant or obligation contained in this Agreement or in the Proxy, Parent shall be entitled (in addition to any other remedy that may be available to it, including monetary damages) to seek and obtain (a) a decree or order of specific performance to enforce the observance and performance of such covenant or obligation, and (b) an injunction restraining such breach or threatened breach. Stockholder further agrees that neither Parent nor any other Person shall be required to obtain, furnish or post any bond or similar instrument in connection with or as a condition to obtaining any remedy referred to in this Section 7(c), and Stockholder irrevocably waives any right he or it may have to require the obtaining, furnishing or posting of any such bond or similar instrument.

        (d)   Waiver. No failure on the part of Parent to exercise any power, right, privilege or remedy under this Agreement, and no delay on the part of Parent in exercising any power, right, privilege or remedy under this Agreement, shall operate as a waiver of such power, right, privilege or remedy; and no single or partial exercise of any such power, right, privilege or remedy shall preclude any other or further exercise thereof or of any other power, right, privilege or remedy. Parent shall not be deemed to have waived any claim available to Parent arising out of this Agreement, or any power, right, privilege or remedy of Parent under this Agreement, unless the waiver of such claim, power, right, privilege or remedy is expressly set forth in a written instrument duly executed and delivered on behalf of Parent; and any such waiver shall not be applicable or have any effect except in the specific instance in which it is given.

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        (e)   Governing Law; Venue. This Agreement and all acts and transactions pursuant hereto and the rights and obligations of the parties hereto shall be governed, construed and interpreted in accordance with the laws of the State of Delaware, without giving effect to principles of conflicts or choice of law. Any legal action or other legal proceeding relating to this Agreement or the Proxy or the enforcement of any provision of this Agreement or the Proxy may be brought or otherwise commenced in any state or federal court located in the State of Delaware. Stockholder:

          (i)  expressly and irrevocably consents and submits to the jurisdiction of each state and federal court located in the State of Delaware in connection with any such legal proceeding;

         (ii)  agrees that service of any process, summons, notice or document by U.S. mail addressed to him or it at the address set forth on the signature page hereof shall constitute effective service of such process, summons, notice or document for purposes of any such legal proceeding;

        (iii)  agrees that each state and federal court located in the State of Delaware shall be deemed to be a convenient forum; and

        (iv)  agrees not to assert (by way of motion, as a defense or otherwise), in any such legal proceeding commenced in any state or federal court located in the State of Delaware, any claim that Stockholder is not subject personally to the jurisdiction of such court, that such legal proceeding has been brought in an inconvenient forum, that the venue of such proceeding is improper or that this Agreement or the subject matter of this Agreement may not be enforced in or by such court.

        Nothing contained in this Section 7(e) shall be deemed to limit or otherwise affect the right of Parent to commence any legal proceeding or otherwise proceed against Stockholder in any other forum or jurisdiction.

        HOLDER IRREVOCABLY WAIVES THE RIGHT TO A JURY TRIAL IN CONNECTION WITH ANY LEGAL PROCEEDING RELATING TO THIS AGREEMENT OR THE PROXY OR THE ENFORCEMENT OF ANY PROVISION OF THIS AGREEMENT OR THE PROXY.

        (f)    Counterparts. This Agreement may be executed in two or more counterparts (including by facsimile), each of which shall be deemed an original and all of which together shall constitute one instrument.

        (g)   Entire Agreement. This Agreement, the Proxy and any other documents delivered by the parties in connection herewith constitute the entire agreement between the parties with respect to the subject matter hereof and thereof and supersede all prior agreements and understandings between the parties with respect thereto. No addition to or modification of any provision of this Agreement shall be binding upon either party unless made in writing and signed by both parties.

        (h)   Titles and Subtitles. The titles and subtitles used in this Agreement are used for convenience only and are not to be considered in construing or interpreting this Agreement.

        (i)    Notices. Any notice required or permitted by this Agreement shall be in writing and shall be deemed sufficient upon receipt, when delivered personally or by courier, overnight delivery service or confirmed facsimile, or forty-eight (48) hours after being deposited in the regular mail as certified or registered mail (airmail if sent internationally) with postage prepaid, if such notice is addressed to the party to be notified at such party's address or facsimile number as set forth below, or as subsequently modified by written notice.

        (j)    Attorneys' Fees. If any legal action or other legal proceeding relating to this Agreement or the enforcement of any provision of this Agreement is brought against Stockholder, the prevailing party shall be entitled to recover reasonable attorneys' fees, costs and disbursements (in addition to any other relief to which the prevailing party may be entitled).

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        (k)   Severability. If one or more provisions of this Agreement are held to be unenforceable under applicable law, the parties agree to renegotiate such provision in good faith, in order to maintain the economic position enjoyed by each party as close as possible to that under the provision rendered unenforceable. In the event that the parties cannot reach a mutually agreeable and enforceable replacement for such provision, then (i) such provision shall be excluded from this Agreement, (ii) the balance of the Agreement shall be interpreted as if such provision were so excluded and (iii) the balance of the Agreement shall be enforceable in accordance with its terms.

        (l)    Construction.

          (i)  For purposes of this Agreement, whenever the context requires: the singular number shall include the plural, and vice versa; the masculine gender shall include the feminine and neuter genders; the feminine gender shall include the masculine and neuter genders; and the neuter gender shall include masculine and feminine genders.

         (ii)  The parties agree that any rule of construction to the effect that ambiguities are to be resolved against the drafting party shall not be applied in the construction or interpretation of this Agreement.

        (iii)  As used in this Agreement, the words "include" and "including," and variations thereof, shall not be deemed to be terms of limitation, but rather shall be deemed to be followed by the words "without limitation."

        (iv)  Except as otherwise indicated, all references in this Agreement to "Sections" and "Exhibits" are intended to refer to Sections of this Agreement and Exhibits to this Agreement.

        8.    Certain Definitions.    For purposes of this Agreement,

        (a)   "Company Common Stock" shall mean the common stock, par value $0.0001 per share, of the Company.

        (b)   Stockholder shall be deemed to "Own" or to have acquired "Ownership" of a security if Stockholder is the "beneficial owner" within the meaning of Rule 13d-3 under the Securities Exchange Act of 1934 of such security.

        (c)   "Person" shall mean any (i) individual, (ii) corporation, limited liability company, partnership or other entity, or (iii) Governmental Body.

        (d)   "Subject Securities" shall mean: (i) all securities of the Company (including all shares of Company Common Stock and all, options, warrants and other rights to acquire shares of Company Common Stock) Owned by Stockholder as of the date of this Agreement; and (ii) all additional securities of the Company (including all additional shares of Company Common Stock and all additional options, warrants and other rights to acquire shares of Company Common Stock) of which Stockholder acquires Ownership during the period from the date of this Agreement through the Termination Date.

        (e)   The term "Termination Date" means the earlier to occur of the date of the consummation of the transactions contemplated by the Merger Agreement or the date the Merger Agreement terminates in accordance with its terms.

        (f)    A Person shall be deemed to have a effected a "Transfer" of a security if such Person directly or indirectly: (i) sells, pledges, encumbers, grants an option with respect to, transfers or disposes of such security or any interest in such security to any Person other than Parent; (ii) enters into an agreement or commitment contemplating the possible sale of, pledge of, encumbrance of, grant of an option with respect to, transfer of or disposition of such security or any interest therein to any Person other than Parent; or (iii) reduces such Person's beneficial ownership of, interest in or risk relating to such security.

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        The parties have caused this Agreement to be duly executed on the date first above written.

PARENT:

TUT SYSTEMS, INC.

By:

Name:

Title:

Address for notices:

STOCKHOLDER:

Name:

Address for notices:

Shares Held of Record Options and Other Rights Additional Securities Beneficially Owned

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IRREVOCABLE PROXY

        The undersigned stockholder (the "Stockholder") of Cosine Communications, Inc., a Delaware corporation (the "Company"), hereby irrevocably (to the full extent permitted by Section 212 of the Delaware General Corporation Law) appoints Salvatore D'Auria and Randall K. Gausman, of TUT Systems, Inc., a Delaware corporation ("Parent"), and each of them, as the sole and exclusive attorneys and proxies of the undersigned, with full power of substitution and resubstitution, to vote and exercise all voting and related rights expressly provided herein (to the full extent that the undersigned is entitled to do so) with respect to (i) the outstanding shares of capital stock of the Company owned of record by the Stockholder as of the date of this proxy, which shares are specified on the final page of this proxy, and (ii) any and all other shares of capital stock of the Company which the Stockholder may acquire on or after the date hereof. (The shares of the capital stock of the Company referred to in clauses "(i)" and "(ii)" of the immediately preceding sentence are collectively referred to as the "Shares.") Upon the undersigned's execution of this Proxy, any and all prior proxies given by the undersigned with respect to any Shares are hereby revoked and the undersigned agrees not to grant any subsequent proxies with respect to the Shares at any time prior to the Termination Date (as defined below).

        This Proxy is irrevocable (to the extent permitted by Section 212 of the Delaware General Corporation Law), is coupled with an interest and is granted pursuant to that certain Voting Agreement of even date herewith, by and between Parent and the undersigned stockholder, and is granted in consideration of Parent entering into that certain Agreement and Plan of Merger and Reorganization (the "Merger Agreement"), of even date herewith, by and among the Company, Parent and Cadillac Merger Corporation, a Delaware corporation ("Merger Sub"). The Merger Agreement provides for the merger of Merger Sub with and into the Company (the "Merger"). As used herein, the term "Termination Date" shall mean the earlier to occur of (i) the date and time as the Merger shall become effective in accordance with the terms and provisions of the Merger Agreement, or (ii) the date the Merger Agreement shall terminate in accordance with its terms.

        The attorneys and proxies named above, and each of them, are hereby authorized and empowered by the undersigned, at any time prior to the Termination Date, to act as the undersigned's attorney and proxy to vote the Shares, and to exercise all voting and other rights of the undersigned with respect to the Shares (including, without limitation, the power to execute and deliver written consents pursuant to Section 228 of the Delaware General Corporation Law), at every annual, special or adjourned meeting of the stockholders of the Company and in every written consent in lieu of such meeting: (i) in favor of approval and adoption of the Merger and the Merger Agreement and in favor of any matter that could reasonably be expected to facilitate the Merger, (ii) against any proposal for any Acquisition Transaction, other than the Merger, between the Company and any person or entity (other than Parent or Merger Sub) and (iii) against any other action or agreement that would result in a breach of any covenant, representation or warranty or any other obligation or agreement of the Company under the Merger Agreement or which could result in any of the conditions to the consummation of the Merger under the Merger Agreement not being fulfilled.

        This proxy shall be binding upon the heirs, estate, executors, personal representatives, successors and assigns of the Stockholder (including any transferee of any of the Shares).

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        If any provision of this proxy or any part of any such provision is held under any circumstances to be invalid or unenforceable in any jurisdiction, then (a) such provision or part thereof shall, with respect to such circumstances and in such jurisdiction, be deemed amended to conform to applicable laws so as to be valid and enforceable to the fullest possible extent, (b) the invalidity or unenforceability of such provision or part thereof under such circumstances and in such jurisdiction shall not affect the validity or enforceability of such provision or part thereof under any other circumstances or in any other jurisdiction, and (c) the invalidity or unenforceability of such provision or part thereof shall not affect the validity or enforceability of the remainder of such provision or the validity or enforceability of any other provision of this proxy. Each provision of this proxy is separable from every other provision of this proxy, and each part of each provision of this proxy is separable from every other part of such provision.

Dated: January    , 2005

(Signature of Stockholder)

(Print Name of Stockholder)

Number of shares of common stock of the Company owned of record as of the date of this proxy:

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