<PAGE>   1
                                                                    EXHIBIT 10.2

February 26, 2001

Mr. Terrence A. Zielinski
PO Box 9017
Coral Springs, FL 33075

Dear Terry:

This letter sets forth the agreement ("Agreement") between you and CyberGuard
Corporation ("CyberGuard" or "Company") regarding your retirement from the
Company. We agree that your last day is February 28, 2001 (for the purposes of
this Agreement, "Termination Date").

1.   SALARY UNTIL TERMINATION DATE. Prior to the Termination Date, you will
     continue to be paid your regular salary, and this Agreement shall have no
     effect upon those payments.

2.   SEVERANCE PAYMENTS AFTER TERMINATION DATE. After the Termination Date,
     CyberGuard will pay you an aggregate amount of $55,211.60 (less tax
     withholding), in accordance with the regular payroll practices of the
     Company, as though you had continued to work for CyberGuard through June
     30, 2001. No bonus will be paid, and you acknowledge that none is owed.

3.   ACCRUED PAID-TIME-OFF. The total amount of accrued paid-time-off pay to
     which you will be entitled as of your Termination Date is $29,203.45 (less
     tax withholding).

4.   NET AMOUNT PAYMENT. The total amount payable to you after the Termination
     Date (before withholding for taxes) is $84,415.05 (representing the
     aggregate of the amounts described in paragraphs 2 and 3 above) and will be
     payable as follows: (1) the $29,203.45 (less tax withholding) payment under
     paragraph 3 will be paid to you in the final paycheck you will receive as
     an employee of CyberGuard; and (2) the $55,211.60 (less tax withholding)
     payment under paragraph 2 will be paid to you in approximately equal
     payments, in accordance with CyberGuard's regular payroll schedules and
     practices, beginning after the effective date of this Agreement.

5.   STOCK OPTIONS. Your option to purchase an aggregate of 150,000 shares of
     CyberGuard Common Stock at $1.31 per share is fully vested and exercisable,
     and we agree that your option to purchase an aggregate of 25,000 shares at
     $6.50 per share of CyberGuard Common Stock is fully vested and immediately
     exercisable as of the Termination Date (collectively, "Options"). The
     Options will remain exercisable through June 30, 2003, or the Options'
     respective expirations, whichever comes first.

6.   WARRANT. Your rights under the Common Stock Purchase Warrant issued to you
     by CyberGuard on August 26, 1999 ("Warrant") will remain in full force and
     effect, and will be unaffected by this Agreement.

7.   INSURANCE. Your coverage for insurance under CyberGuard plans (including
     medical, dental and life) will remain in place until your Termination Date.
     If you wish to continue the coverage after your Termination Date, you will
     pay the full amount of the premiums (including any incremental expenses in
     connection with pre-existing conditions and increases in premiums as
     permitted or required under COBRA). A separate notice under COBRA will be
     sent to you from the CyberGuard Personnel Department regarding insurance.




                                       1
<PAGE>   2

8.   401-k PLAN. Your participation in the CyberGuard 401-k Plan will cease at
     the Termination Date. Upon request, you will sign an appropriate letter
     addressed to the 401-k Plan administrators directing that no further
     payments be accepted on your behalf. Your vesting in the 401-k plan shall
     be determined as of the Termination Date, unless the 401-k Plan or ERISA
     requires otherwise.

9.   RETURN OF EQUIPMENT. You agree to return, promptly upon request, any
     CyberGuard equipment that you may have (such as a notebook or other
     computers), and CyberGuard credit cards and key cards.

10.  RESIGNATION. We agree that your resignation as Chief Financial Officer,
     Vice President of Finance, and Treasurer of CyberGuard and from any other
     officer and director position that you may have held at CyberGuard and/or
     its subsidiaries shall be effective as of February 13, 2001.

11.  NO OTHER RIGHTS TO COMPENSATION. You acknowledge that once the payments set
     forth in paragraph 4 of this letter are paid in full, you will have been
     paid in full all amounts due or owed to you in the nature of salary, bonus,
     severance, vacation pay, personal leave, sick leave, paid-time-off, living
     expenses and other compensation of any kind whatsoever, for all services
     rendered to CyberGuard as employee or in any other capacity whatsoever. You
     also acknowledge that other than the Options and the Warrant, CyberGuard
     has granted you no other options, warrants, restricted stock or rights of
     any kind to acquire capital stock of CyberGuard.

12.  CERTAIN COMMUNICATIONS. CyberGuard and you agree that neither of us will
     say, write or communicate in any manner to any person or entity anything
     substantially derogatory about the other, regardless of the truth or
     falsity of the information. Of course, nothing in this section shall be
     construed to prevent either party from testifying truthfully under oath if
     compelled to do so by court order or other legal compulsion. In this
     connection, for purposes hereof, "CyberGuard" means and includes CyberGuard
     Corporation, and its current officers, directors, employees, affiliates and
     representatives.

13.  NON-SOLICITATION. You agree that for six (6) months after the Termination
     Date you will not, without the prior written consent of CyberGuard,
     directly or indirectly, for yourself or for any other person, firm,
     corporation, partnership, association or other entity (a) attempt to
     employ, employ or enter into any contractual arrangement with any employee
     or former employee of CyberGuard, its affiliates, subsidiaries or
     predecessors in interest, unless such employee or former employee has not
     been employed by CyberGuard, its affiliates, subsidiaries or predecessors
     in interest during the 120 days prior to your attempt to employ him, or (b)
     call on or solicit any of the actual or currently targeted prospective
     customers of CyberGuard for the purpose of offering any product or service
     that is in direct competition with the products or services of CyberGuard.

14.  NON-COMPETITION. You agree that for six (6) months after the Termination
     Date, you shall not, directly or indirectly, be employed by, act as a
     consultant or contractor for, be involved in a venture with, or otherwise
     engage in any business enterprise or employment, with any of the following
     companies: Axent Technologies, Inc., Check Point Software Technologies,
     Inc, Fore Systems, Inc., Network Associates, Inc., Secure Computing Corp.,
     or Network-1 Security Solutions, Inc. In the event that these geographical
     or temporal restrictions are judicially determined to be unreasonable, we
     agree that these restrictions shall be judicially reformed to the maximum
     restrictions which are reasonable.

15.  CONFIDENTIALITY; TERMINATION OF THE EMPLOYMENT AGREEMENT. Paragraph 16
     (governing confidential information) of the Employment Agreement between
     you and the Company dated September 8, 1998 ("Employment Agreement"), shall
     remain in full force and effect for two years from the date hereof.
     Otherwise, in all other respects, the Employment Agreement is hereby
     terminated and shall be of no further force or effect.





                                       2
<PAGE>   3

16.  INJUNCTION/SPECIFIC PERFORMANCE SETOFF. You acknowledge that a breach of
     any of the provisions of Sections 13, 14, or 15 hereof would result in
     immediate and irreparable injury to the Company which cannot be adequately
     or reasonably compensated at law. Therefore, you agree that the Company
     shall be entitled, if any such breach shall occur or be threatened or
     attempted, to a decree of specific performance and to a temporary and
     permanent injunction, without the posting of a bond, enjoining and
     restraining such breach by you or your agents, either directly or
     indirectly, and that such right to injunction shall be cumulative to
     whatever other remedies for actual damages to which the Company is
     entitled. You further agree that the Company may set off against or recoup
     from any amounts due under this Agreement to the extent of any losses
     incurred by the Company as a result of any breach by you of the provisions
     of Sections 13, 14, or 15 hereof.

17.  RELEASE. In order to clearly define the intent of this termination
     arrangement, the following release provisions will become effective as
     described below. You specifically acknowledge and agree as follows:

         (a)  You have been given at least twenty-one (21) full days within
              which to consider this Agreement, including the release set forth
              below;

         (b)  You are advised that you have the right and may consult with an
              attorney prior to executing this Agreement and acknowledge the
              opportunity to consult an attorney;

         (c)  You have seven (7) days following the execution of this Agreement
              to revoke the Agreement and the Agreement will not become
              effective or enforceable until after this seven (7) day period has
              expired;

         (d)  You recognize that you are specifically releasing, among other
              claims, any claims under the Age Discrimination in Employment Act
              of 1967 and all amendments thereto;

         (e)  You entered into this Agreement voluntarily and on your free will;

         (f)  You are not waiving rights or claims that may arise after the date
              this Agreement is executed;

         (g)  In consideration of the execution and delivery of this Agreement,
              and other good and valuable consideration, the receipt and
              sufficiency of which is hereby acknowledged by you ("You"), You
              hereby fully and forever release and discharge CyberGuard and its
              agents, officers, directors, employees, successors and assigns, of
              and from any and all responsibilities, duties, obligations,
              claims, debts, sums of money, accounts or causes of action or
              actions, costs, losses, damages or liabilities of whatsoever
              character, nature, kind or designation in law or in equity,
              absolute or contingent, matured or unmatured, suspected or
              unsuspected, known or unknown, which You or anyone claiming under,
              by or through You now has, ever had or could ever have or become
              entitled to assert against CyberGuard or its agents, officers,
              directors, employees, successors or assigns by reason of any
              conduct, matter, cause, or thing whatsoever; without limiting the
              generality of the foregoing release, You hereby release any claims
              for: (i.) salary, bonus, accrued vacation, paid-time-off, benefits
              or compensation of any kind whatsoever whether arising as an
              employee or otherwise; (ii.) violations of any federal, state or
              municipal employment practices laws, rules or regulations,
              including without limitation laws, rules or regulations regarding
              discriminatory practices, including without limitation, age
              discrimination; and (iii.) breaches of any agreements of any kind
              whatsoever between You and CyberGuard. If at anytime CyberGuard
              fails to make the payments required in paragraphs 1, 2, 3 and 4
              above, You may give CyberGuard written notice of Your intention to
              cancel this release, at which time CyberGuard shall have ten days
              to make any delinquent payments to cure the default, or this
              release shall terminate. This release shall not affect Your rights
              or CyberGuard's obligations under the Warrant, or Your rights to
              exercise the Options.




                                       3
<PAGE>   4

18.  MISCELLANEOUS. With the exception of the Warrant, this Agreement
     constitutes the entire agreement between us, and all prior agreements,
     understandings, writings and commitments are terminated and merged into
     this Agreement. This Agreement shall not be amended except by the written
     agreement by CyberGuard and you. This Agreement shall be binding upon, and
     shall inure to the benefit of, each of us, and our permitted respective
     heirs, legal representatives, successors and assigns. This Agreement may be
     executed in counterparts, all of which together shall constitute one and
     the same instrument. Words such as "hereof", "hereunder", "hereby' "herein"
     and similar words refer to this Agreement as a whole and not to any
     particular section of this Agreement. This Agreement shall be governed by,
     and construed and enforced in accordance with the laws of the State of
     Florida, without giving effect to the choice of law provisions thereof. Any
     and all disputes arising hereunder shall be decided in the courts of the
     State of Florida or the federal courts located therein. Each of us agrees
     to submit to personal jurisdiction and to waive any objection as to venue
     in Broward County, Florida.

If you agree with the terms of this letter, please indicate by signing in the
space provided below.

Sincerely,


Scott J. Hammack
Chief Executive Officer
CyberGuard Corporation

AGREED AND ACCEPTED THIS 28TH DAY OF FEBRUARY, 2001.



-----------------------------------
Terrence A. Zielinski





                                       4