<PAGE>
EXHIBIT 5.1
December 22, 2000
SonicWALL, Inc.
1160 Bordeaux Drive
Sunnyvale, CA 94089
Re: SonicWALL, Inc. - Registration Statement on Form S-8 for
--------------------------------------------------------
Offering of an Aggregate of 2,200,000 Shares of Common Stock
------------------------------------------------------------
Gentlemen:
We have acted as counsel to SonicWALL, Inc., a California corporation
(the "Company") in connection with the Registration Statement on Form S-8 to be
filed on December 22, 2000 (the "Registration Statement"), under the Securities
Act of 1933, as amended (the "Act"), covering 2,200,000 shares of the Company's
Common Stock, no par value (the "Shares"), consisting of an additional 2,000,000
shares authorized for issuance under the Company's 1998 Stock Option Plan and
200,000 shares authorized for issuance under the Company's 1999 Employee Stock
Purchase Plan (collectively, the "Plans").
This opinion is being furnished in accordance with the requirements of
Item 8 of Form S-8 and Item 601(b)(5)(i) of Regulation S-K.
We have reviewed the Company's charter documents, the corporate
proceedings taken by the Company in connection with the establishment of the
Plans and originals, or certified, conformed or reproduction copies, of all such
records, agreements, instruments and documents as we have deemed relevant or
necessary as the basis for the opinion hereinafter expressed. In all such
examinations, we have assumed the genuineness of all signatures on original or
certified copies and the conformity to original or certified copies of all
copies submitted to us as conformed or reproduction copies. As to various
questions of fact relevant to such opinion, we have relied upon, and assumed the
accuracy of, certificates and oral or written statements and other information
of or from public officials, officers or representatives of the Company, and
others.
Based upon the foregoing review, we are of the opinion that the Shares,
when issued, delivered and paid for in accordance with the terms of the Plans,
the provisions of the option agreements or stock purchase rights duly authorized
<PAGE>
December 22, 2000
Page 2
under the Plans and the Registration Statement, will be duly authorized and
validly issued, fully paid and non-assessable.
We hereby consent to the filing of this opinion as Exhibit 5.1 to the
Registration Statement, and further consent to the use of our name wherever
appearing in the Registration Statement and any subsequent Amendment thereto.
This opinion letter is rendered as of the date first written above and
we disclaim any obligation to advise you of facts, circumstances, events or
developments which hereafter may be brought to our attention and which may
alter, affect or modify the opinion expressed herein. Our opinion is expressly
limited to the matters set forth above and we render no opinion, whether by
implication or otherwise, as to any other matters relating to the Company, the
Plans or the Shares.
Very truly yours,
/s/ Manatt, Phelps & Phillips, LLP
Manatt, Phelps & Phillips, LLP
