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Exhibit 2.2 AMENDMENT NO. 1 TO
AGREEMENT AND PLAN OF MERGER AMENDMENT
NO. 1 TO AGREEMENT AND PLAN OF MERGER (this
Amendment ) is dated as of February 14, 2005, by and among Tut Systems, Inc., a
Delaware corporation (Parent), Cadillac Merger Sub, a Delaware corporation
(Merger Sub), and CoSine Communications, Inc., a Delaware corporation (the
Company). RECITALS A. The parties to this Amendment entered into an Agreement and Plan of
Merger dated as of January 7, 2005 (the Original
Agreement) which provided
that, upon the terms and subject to the conditions set forth in the Original
Agreement and in accordance with Delaware General Corporation Law
(The DGCL),
Parent and Company would enter into a merger transaction pursuant to which Merger
Sub would merge with and into the Company, with the Company continuing after such
merger as the surviving corporation and a wholly owned subsidiary of Parent. B. The parties to this Amendment desire to amend and restate the Original
Agreement, by means of this Amendment, to modify the structure of the merger so
that the Company would merge with and into Merger Sub, with Merger Sub continuing
after such merger as the surviving corporation and a wholly owned subsidiary of
Parent, (the Merger). AGREEMENT NOW,
THEREFORE, in consideration of the foregoing and the mutual covenants
and agreements herein contained, and intending to be legally bound hereby,
Parent, Merger Sub and the Company hereby agree to amend the Original Agreement
as follows: 1.
Definitions and Cross References. Unless specified herein, each
capitalized term shall have the meaning assigned to it in the Original Agreement
and each reference to a Section or Article shall refer to the corresponding
Section or Article in the Original Agreement. 2. Section 1.1. Section 1.1 is amended by replacing the section, in
its entirety with the following: Section 1.1
Merger of Company into Merger Sub. At the Effective
Time (as defined in Section 1.2) and upon the terms and subject to the
conditions set forth in this Agreement and the applicable provisions of the
General Corporation Law of the State of Delaware (the DGCL), the Company shall
be merged with and into Merger Sub, the separate corporate existence of the
Company shall cease and Merger Sub shall continue as the surviving corporation.
Merger Sub, as the surviving corporation after the Merger, is hereinafter
sometimes referred to as the Surviving Corporation. 3. Section 1.6. Section 1.6 is amended by replacing subsection (d)
in its entirety with the following: 1




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(d) Capital Stock of Merger sub. At the Effective Time, each stock certificate
representing common stock, $0.01 par value, of Merger Sub (Merger Sub Common
Stock) issued and outstanding immediately prior to the Effective Time shall
continue to evidence ownership of such shares of capital stock of the Surviving
Corporation. 4. Miscellaneous. 4.1 Continuing Effect. This Amendment shall be effective for all
purposes as of the Effective Date. Except as otherwise expressly modified by
this Amendment, the Original Agreement shall remain in full force and effect
in accordance with its terms. 4.2
Governing Laws. This Amendment shall be governed by, interpreted and
construed in accordance with the laws of the State of Delaware, without regard
to conflict of law principles. 4.3 Counterparts. This Amendment may be executed in counterparts,
each of which shall be deemed to be an original and together shall be deemed to
be one and the same document. [SIGNATURE PAGE FOLLOWS] 2




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IN WITNESS WHEREOF, the Company, Parent and Merger Sub have caused
this Amendment to the Original Agreement to be executed and delivered by their
respective officers thereunto duly authorized, all as of the date first written
above. TUT SYSTEMS, INC.By:
    /s/ Randall GausmanName:Title: COSINE COMMUNICATIONS, INC.By:

/s/
Terry GibsonName:Title: CADILLAC MERGER SUB, INC.By:
    /s/ Randall GausmanName:Title: 3