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                                  May 21, 1996




Shiva Corporation
28 Crosby Drive
Bedford, MA 01730

      Re:   Registration Statement on Form S-8
            ----------------------------------

Gentlemen:

      We have examined the Registration Statement on Form S-8 to be filed by you
with the Securities and Exchange Commission on or about May 21, 1996 (the
"Registration Statement") in connection with the registration under the
Securities Act of 1933, as amended, of 4,366,668 shares (the "Shares") of your
Common Stock under the 1988 Stock Plan (the "Plan"). As your counsel in
connection with this transaction, we have examined the proceedings taken and are
familiar with the proceedings proposed to be taken by you in connection with the
issuance and sale of the Shares pursuant to the Plan.

      It is our opinion that, when issued and sold in the manner described in
the Plan and pursuant to the agreements which accompany each grant under the
Plan, the Shares will be legally and validly issued, fully-paid and
non-assessable.

      We consent to the inclusion of this opinion as an exhibit to the
Registration Statement, and further consent to the use of our name wherever
appearing in the Registration Statement and any amendments thereto.



                                    Very truly yours,

                                    /s/ Testa, Hurwitz & Thibeault, LLP
                    
                                    TESTA, HURWITZ & THIBEAULT, LLP