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                                                                   EXHIBIT 10.18

                          CONCORD COMMUNICATIONS, INC.

         NON-QUALIFIED STOCK OPTION AGREEMENT FOR NON-EMPLOYEE DIRECTORS

      1. Grant Under 1997 Non-Employee Director Stock Option Plan. This option
is granted pursuant to and is governed by the Company's 1997 Non-Employee
Director Stock Option Plan (the "Plan") and, unless the context otherwise
requires, terms used herein shall have the meanings assigned to them in the
Plan. Determinations made in connection with this option pursuant to the Plan
shall be governed by the Plan as it exists on the date hereof. In the event of
any conflict between this Agreement and the provisions of the Plan, the Plan
shall govern.

      2. Grant as Non-Qualified Option; Other Options. This option is intended
to be a non-qualified option (rather than an incentive stock option) granted
pursuant to Section 4(b) of the Plan, and the Board of Directors of the Company
(the "Board") intends to take appropriate action, if necessary, to achieve this
result. This option is in addition to any other options heretofore or hereafter
granted to the Optionee by the Company, but a duplicate original of this
instrument shall not affect the grant of another option.

      3. Exercise of Option if Service as a Director Continues. Unless sooner
terminated pursuant to Section 4 hereof, this option shall vest in the Optionee
and thus become exercisable in accordance with the vesting schedule set forth in
Section 7 of the Plan, provided that the Optionee has continuously served as a
member of the Board through such vesting date. This option shall expire on the
date, which is ten (10) years from the date this option is granted.

      4. Termination of Option Rights.

            (a)   In the event that Optionee ceases to be a member of the Board
                  for any reason other than death or permanent disability, any
                  then unexercised portion of this option shall, to the extent
                  not then vested, immediately terminate and become void. Any
                  portion of this option which is vested but has not been
                  exercised at the time the Optionee so ceases to be a member of
                  the Board may be exercised, to the extent it is then vested,
                  by the Optionee within 60 days of the date the Optionee ceased
                  to be a member of the Board, and this option shall terminate
                  after such 60 days has expired.

            (b)   In the event that the Optionee ceases to be a member of the
                  Board by reason of his or her permanent disability or death,
                  this option may be exercised, to the extent of the number of
                  shares with respect to which he or she could have exercised it
                  on the date of death or permanent disability, by the Optionee
                  (or by Optionee's personal representative, heir or legatee, in
                  the event of death) until the scheduled expiration date of the
                  option.

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      5. Exercise. To the extent then exercisable, the Optionee may exercise
this option in whole or in part at any time and from time to time as provided by
the terms of this Agreement and the Plan, except that this option may not be
exercised for a fraction of a share unless such exercise is with respect to the
final installment of stock subject to this option and a fractional share (or
cash in lieu thereof) would otherwise be required to be issued to permit the
Optionee to exercise completely such final installment. Any fractional share
with respect to which an installment of this option cannot be exercised because
of the limitation contained in the preceding sentence shall remain subject to
this option and shall be available for later purchase by the Optionee in
accordance with the terms hereof. There shall be no such exercise at any one
time as to fewer than one hundred (100) shares or all of the remaining shares
then purchasable by the person or persons exercising the option, if fewer than
one hundred (100) shares.

      6. Payment of Price. The option price is payable in United States dollars
and may be paid: (a) in cash or by check, or any combination of the foregoing,
equal in amount to the option price; (b) in whole or in part in shares of the
Common Stock of the Company already owned by the person or persons exercising
the option or shares subject to the option being exercised (subject to such
restrictions and guidelines as the Board may adopt from time to time), valued at
fair market value determined in accordance with the provisions of Section 5 of
the Plan; or (c) consistent with applicable law, through the delivery of an
assignment to the Company of a sufficient amount of the proceeds from the sale
of Option Shares acquired upon exercise of this option and an authorization to
the broker or selling agent to pay that amount to the Company, which shall be at
the Optionee's direction at the time of exercise.

      7. Method of Exercising Option. Subject to the terms and conditions of the
Plan and this Agreement, this option may be exercised by written notice to the
Company by mail or in person, addressed to the Chief Financing Officer at 400
Nickerson Road, Marlboro, Massachusetts 01752, its principal executive offices.
Such notice shall state the election to exercise this option and the number of
shares in respect of which it is being exercised and shall be signed by the
person or persons so exercising this option. Such notice shall be accompanied by
payment of the full purchase price of such shares. The Company's transfer agent
shall, on behalf of the Company, prepare a certificate or certificates
representing Option Shares acquired upon exercise of this option, shall register
the Optionee (or the Optionee's personal representative, heir or legatee if this
option is being exercised pursuant to Section 4 hereof) as the owner of the
Option Shares on the books of the Company and shall cause the fully executed
certificate(s) representing such shares to be delivered to the Optionee (or the
Optionee's personal representative, heir or legatee if this option is being
exercised pursuant to Section 4 hereof) as soon as practicable after payment of
the option price in full. In the event this option shall be exercised, pursuant
to Section 4 hereof, by any person or persons other than the Optionee, such
notice shall be accompanied by appropriate proof of the right of such person or
persons to exercise this option. All shares that shall be purchased upon the
exercise of this option as provided herein shall be fully paid and
non-assessable.

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      8. Option Not Transferable. This option is not transferable or assignable
except by will or by the laws of descent and distribution or pursuant to a
domestic relations order. During the Optionee's lifetime only the Optionee can
exercise the option.

      9. No Obligation to Exercise Option. The grant and acceptance of this
option imposes no obligation on the Optionee to exercise it.

      10. No Rights As Stockholder until Exercise. The Optionee shall have no
rights as a stockholder with respect to any of the Option Shares until a stock
certificate therefore has been issued to the Optionee and is fully paid for.
Except as is expressly provided in Section 10 of the Plan with respect to
certain changes in the capitalization of the Company, no adjustment shall be
made for dividends or similar rights for which the record date is prior to the
date such stock certificate is issued.

      11. Capital Changes and Business Successions. The Plan contains extensive
provisions designed to preserve options at full value in a number of
contingencies. Therefore, provisions in the Plan for adjustment with respect to
stock subject to options and the related provisions with respect to successors
to the business of the Company are hereby made applicable hereunder and are
incorporated herein by reference.

      12. Withholding Taxes. The Optionee hereby acknowledges that the Company
may be required to withhold federal, state and local taxes attributable to the
Optionee's exercise of any installment of this option and therefore agrees to
pay the Company any such amounts upon the Company's request.

      13. Agreement to Purchase for Investment. By acceptance of this option,
the Optionee agrees that a purchase of shares under this option will be made for
investment and will not be made with a view to their distribution, as that term
is used in the Securities Act of 1933, unless in the opinion of counsel to the
Company such transaction is in compliance with or exempt from the registration
and prospectus requirements of that Act. The Optionee agrees to sign a
certification to such effect at the time of exercising this option and agrees
that the certificate for the shares so purchased may be enscribed with a legend
to ensure compliance with the Securities Act of 1933 and with any other
applicable securities laws. The certificates representing such shares shall
carry such appropriate legend and such written instructions with respect thereto
shall be given to the Company's transfer agent, as may be deemed necessary or
advisable by counsel to the Company in order to comply with the requirements of
the Securities Act of 1933 or any state securities laws.

      14. Resale Restrictions. Under no circumstances may shares acquired
hereunder be disposed of on or prior to the date that is six months after the
date that this option was granted.

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      15. Governing Law. This Agreement constitutes the entire agreement of the
parties with respect to the subject matter hereof, supersedes any and all
correspondence, discussions or agreements between the parties regarding equity
incentives for the Optionee and satisfies all of the Company's obligations with
respect to the grant of equity incentives to the Optionee as in effect on the
date hereof.

      IN WITNESS WHEREOF the Company and the Optionee have caused this
instrument to be executed, and the Optionee whose signature appears below
acknowledges receipt of a copy of the Plan and acceptance of an original copy of
this Agreement.

                                                    CONCORD COMMUNICATIONS, INC.
                                                    400 Nickerson Road
                                                    Marlboro, MA  01752

                                                    By: ________________________
                                                        Name:
                                                        Title:

                                                    ____________________________
                                                    (OPTIONEE)

                                                    ____________________________
                                                    Street Address

                                                    ____________________________
                                                    City        State   Zip Code<PAGE>

                                                                   Exhibit 10.25

                          CONCORD COMMUNICATIONS, INC.

                                    Employee

                         Non-Qualified Option Agreement

1.    Grant Under 1997 Stock Plan

      This Option Agreement is effective only when attached to a Notice of Grant
      of Stock Options (the "Notice") signed on behalf of Concord
      Communications, Inc. (the "Company") and by the option holder (the
      "Employee"). The option granted under the Notice (the "Option") is granted
      pursuant to and is governed by the Company's 1997 Stock Plan (the e Plan")
      and , unless the context otherwise requires, terms used herein shall have
      the same meaning as in the Plan. Determinations made in connection with
      this Option pursuant to the Plan shall be governed by the Plan as it
      exists on this date. In the event of any inconsistency or conflict between
      this Agreement and the Plan, the terms of the Plan shall govern. This
      option shall not be treated as an incentive stock option.

2.    Other Options

      This Option is in addition to any other Options heretofore or hereafter
      granted to the Employee by the Company, but a duplicate original of this
      instrument shall not effect the grant of another Option.

3.    Extent of Option if Employment Continues

      If the Employee continues to be employed by the Company on the date(s)
      described in the Notice, the Employee may exercise the Option for the
      number of shares indicated. Shares which vest "quarterly" vest in equal
      installments as of the end of each three-month period during the interval
      described in the Notice.

      The foregoing rights are cumulative and, while the Employee continues to
      be employed by the Company, may be exercised up to and including the time
      of Expiration set forth in the Notice. All of the foregoing rights are
      subject to Sections 4 and 5 of this Agreement, as appropriate, if the
      Employee ceases to be employed by the Company or becomes disabled or dies
      while in the employ of the Company.

      In the event that the Company becomes a party to a merger, consolidation,
      reorganization or similar corporate transaction in which the Company is
      not, in effect, the acquiring corporation, or which is not solely a
      consolidation with the Company's parent, or shall determine to liquidate
      or dissolve, the Company agrees to so advise the Employee in writing, and
      upon the giving of such notice, the "Full Vest" date(s) set forth in the
      Notice

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      shall be reduced by eighteen (18) months, but in no event to a date
      earlier than the date of grant of the Option.

      4.    Termination of Employment

      If the Employee ceases to be employed by the Company other than by reason
      of death or disability, the Option shall terminate after the passage of
      sixty (60) days from the date employment ceases, but in no event later
      than the scheduled expiration date. In such a case, the Employee's only
      rights hereunder shall be those which are properly exercised before the
      termination of the Option.

      5.    Death or Disability

      If the Employee dies while in the employ of the Company, the Option may be
      exercised, to the extent of the number of shares with respect to which the
      Employee could have exercised it on the date of his death, by his estate,
      personal representative, or beneficiary to whom the Option has been
      assigned pursuant to Section 9, at any time within 180 days after the date
      of death, but not later than the scheduled expiration date. If the
      Employee ceases to be employed by the Company by reason of his disability
      (as defined in the Plan), the Option may be exercised to the extent of the
      number of shares with respect to which he could have exercised it on the
      date of the termination of his employment, at any time within 180 days
      after such termination, but not later than the scheduled expiration date.
      At the expiration of such 180 day period or the scheduled expiration date,
      whichever is the earlier, the Option shall terminate and the only rights
      hereunder shall be those as to which the Option was properly exercised
      before such termination.

      6.    Partial Exercise

      Exercise of the Option up to the extent stated in the Notice of Grant may
      be made in part at any time and from time to time within the above limits,
      except that the Option may not be exercised for a fraction of a share.

      7.    Agreement to Purchase for Investment

      By acceptance of the Option, the Employee agrees that a purchase of shares
      under the Option will not be made with a view to their distribution, as
      that term is used in the Securities Act of 1933, as amended, unless in the
      opinion of counsel to the Company such distribution is in compliance with
      or exempt from the registration and prospectus requirements of the Act,
      and the Employee agrees if requested to sign a certificate to such effect
      at the time of exercising the Option and agrees that the certificate for
      the shares so purchased may be inscribed with a legend to ensure
      compliance with the Act and with any applicable state securities laws.

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      8.    Method of Exercising Option

            (a) Subject to the terms and conditions of this Agreement, the
      Option may be exercised by written notice to the Company, at the principal
      executive office of the Company, or to such transfer agent as the Company
      shall designate. Such notice shall state the election to exercise the
      Option and the number of shares in respect of which it is being exercised
      and shall be signed by the person or persons so exercising the Option.
      Such notice shall be accompanied by payment of the full purchase price of
      such shares, and the Company shall deliver a certificate or certificates
      representing such shares as soon as practicable after the notice and
      payment have been received.

            (b) The Option price shall be paid in cash or by check or, with the
      consent of the Committee in its sole discretion, in the following manner:

                  (i)   subject to Section 8(c) below, by delivery of shares of
                        the Company's Common Stock having a fair market value
                        (as determined by the Committee) equal as of the date of
                        exercise to the option price;

                  (ii)  by delivery of the Employee's personal recourse note
                        bearing interest payable not less than annually at the
                        rate set forth in the Plan; or

                  (iii) by any combination of the foregoing.

            (c) If the Employee delivers Common Stock held by the Employee ("Old
      Stock") to the Company in full or partial payment of the option price, and
      the Old Stock so delivered is subject to restrictions or limitations
      imposed by agreement between the Employee and the Company, an equivalent
      number of option shares shall be subject to all restrictions and
      limitations applicable to the Old Stock to the extent that the Employee
      paid for the option shares by delivery of Old Stock, in addition to any
      restrictions or limitations imposed by this Agreement. Notwithstanding the
      foregoing, the Employee may not pay any part of the exercise price hereof
      by transferring Common Stock to the Company unless such Common Stock has
      been owned by the Employee free of any substantial risk of forfeiture for
      at least six months.

            (d) The certificate or certificates for the shares as to which the
      Option shall have been so exercised shall be registered in the name of the
      person or persons so exercising the Option (or, if the Option shall be
      exercised by the Employee and if the Employee shall so request in the
      notice exercising the Option, shall be registered in the name of the
      Employee and another person jointly, with right of survivorship) and shall
      be delivered as provided above to or upon the written order of the person
      or persons exercising the Option. In the event the Option shall be
      exercised, pursuant to Section 5 hereof, by any person or persons other
      than the Employee, such notice shall be

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      accompanied by appropriate proof of the right of such person or persons to
      exercise the Option. All shares that shall be purchased upon the exercise
      of the Option as provided herein shall be fully paid and nonassessable.

      9.    Option Not Transferable

      The Option is not transferable or assignable except by will or by the laws
      of descent and distribution. During the Employee's lifetime, only the
      Employee can exercise the Option.

      10.   No Obligation to Exercise Option

      The grant and acceptance of the Option imposes no obligation on the
      Employee to exercise it.

      11.   No Obligation to Continue Employment

      The Company is not by the Plan or the Option obligated to continue the
      Employee in employment.

      12.   No Rights as Stockholder Until Exercise

      The Employee shall have no rights as a stockholder with respect to shares
      subject to the Option until a stock certificate therefor has been issued
      to the Employee and is fully paid for. Except as expressly provided in the
      Plan with respect to certain changes in the capitalization of the Company,
      no adjustment shall be made for dividends or similar rights for which the
      record date is prior to the date such stock certificate is issued.

      13.   Withholding Taxes

      If the Company in its discretion determines that it is obligated to
      withhold any tax in connection with the exercise of this option, or in
      connection with the transfer of, or the lapse of restrictions on, any
      Common Stock or other property acquired pursuant to the Option, the
      Employee hereby agrees that the Company may withhold from the Employee's
      wages or other remuneration the appropriate amount of tax. At the
      discretion of the Company, the amount required to be withheld may be
      withheld in cash from such wages or other remuneration or in kind from the
      Common Stock or other property otherwise deliverable to the Employee on
      exercise of the Option. The Employee further agrees that, if the Company
      does not withhold an amount from the Employee's wages or other
      remuneration sufficient to satisfy the withholding obligation of the
      Company, the Employee will make reimbursement on demand, in cash, for the
      amount underwithheld.

      14.   Arbitration

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      Any dispute, controversy, or claim arising out of, in connection with, or
      relating to the performance of this Agreement or its termination shall be
      settled by arbitration in the Commonwealth of Massachusetts, pursuant to
      the rules then obtaining of the American Arbitration Association. Any
      award shall be final, binding and conclusive upon the parties and a
      judgment rendered thereon may be entered in any court having jurisdiction
      thereof.

      15.   Provision of Documentation to Employee

      By signing the Notice the Employee acknowledges receipt of a copy of this
      Agreement and a copy of the Plan.

      16.   Miscellaneous

            (a) Notices. All communications hereunder shall be in writing and
      shall be deemed given when sent by certified or registered mail, postage
      prepaid, return receipt requested, to the address set forth in the Notice.
      The addresses for such communications may be changed from time to time by
      written notice given in the manner provided for herein.

            (b) Entire Agreement; Modification. The Notice and this Agreement
      constitute the entire agreement between the parties relative to the
      subject matter hereof, and supersede all proposals, written or oral, and
      all other communications between the parties relating to the subject
      matter of this Agreement. This Agreement may be modified, amended or
      rescinded only by a written agreement executed by both parties.

            (c) Severability. The invalidity, illegality or unenforceability of
      any provision of the Notice or this Agreement shall in no way affect the
      validity, legality or enforceability of any other provision.

            (d) Successors and Assigns. The Notice and this Agreement shall be
      binding upon and inure to the benefit of the parties hereto and their
      respective successors and assigns, subject to the limitations set forth in
      Section 9 hereof.

            (e) Governing Law. This Agreement shall be governed by and
      interpreted in accordance with the internal laws of The Commonwealth of
      Massachusetts.

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