<PAGE>

                                                                   EXHIBIT 10.18

NEITHER THIS WARRANT NOR THE SHARES ISSUABLE UPON EXERCISE HEREOF HAVE BEEN
REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE "SECURITIES ACT")
OR ANY OTHER APPLICABLE STATE SECURITIES LAWS IN RELIANCE UPON AN EXEMPTION FROM
THE REGISTRATION REQUIREMENTS OF THE SECURITIES ACT PURSUANT TO REGULATION D AND
SUCH OTHER SECURITIES LAWS. NEITHER THIS WARRANT NOR THE SHARES ISSUABLE UPON
EXERCISE HEREOF MAY BE SOLD, PLEDGED, TRANSFERRED, ENCUMBERED OR OTHERWISE
DISPOSED OF EXCEPT PURSUANT TO AN EFFECTIVE REGISTRATION STATEMENT UNDER THE
SECURITIES ACT OR IN A TRANSACTION WHICH IS EXEMPT FROM REGISTRATION UNDER THE
PROVISIONS OF THE SECURITIES ACT AND ANY APPLICABLE STATE LAWS, AND IN THE CASE
OF AN EXEMPTION, ONLY IF THE COMPANY HAS RECEIVED AN OPINION OF COUNSEL THAT
SUCH TRANSACTION DOES NOT REQUIRE REGISTRATION OF THE WARRANT OR SUCH SHARES,
WHICH OPINION AND WHICH COUNSEL SHALL BE SATISFACTORY TO THE COMPANY IN ITS SOLE
DISCRETION.

                             STOCK PURCHASE WARRANT

                  To Purchase 75,000 Shares of Common Stock of

                          NetLojix Communications, Inc.

THIS CERTIFIES that, for value received, AMRO International, S.A. (the
"Holder"), is entitled, upon the terms and subject to the limitations on
exercise and the conditions hereinafter set forth, at any time on or after
September 1, 2000 (the "Initial Exercise Date") and on or prior to the close
of business on March 1, 2003 (the "Termination Date") but not thereafter, to
subscribe for and purchase from NetLojix Communications, Inc., a corporation
incorporated in the State of Delaware (the "Company"), up to seventy-five
thousand (75,000) shares (the "Warrant Shares") of Common Stock, $.01 par
value, of the Company (the "Common Stock"). The purchase price of one share
of Common Stock (the "Exercise Price") under this Warrant shall be $5.25. The
Exercise Price and the number of shares for which the Warrant is exercisable
shall be subject to adjustment as provided herein. In the event of any
conflict between the terms of this Warrant and the Common Stock and Warrant
Purchase Agreement dated as of March 2, 2000 pursuant to which this Warrant
has been issued (the "Purchase Agreement"), the Purchase Agreement shall
control. Capitalized terms used and not otherwise defined herein shall have
the meanings set forth for such terms in the Purchase Agreement.

                                      E-69
<PAGE>

         1.       TITLE TO WARRANT. Prior to the Termination Date and subject to
compliance with applicable laws, this Warrant and all rights hereunder are
transferable, in whole or in part, at the office or agency of the Company by the
holder hereof in person or by duly authorized attorney, upon surrender of this
Warrant together with the Assignment Form annexed hereto properly endorsed.

         2.       AUTHORIZATION OF SHARES. The Company covenants that all shares
of Common Stock which may be issued upon the exercise of rights represented by
this Warrant will, upon exercise of the rights represented by this Warrant, be
duly authorized, validly issued, fully paid and nonassessable and free from all
taxes, liens and charges in respect of the issue thereof (other than taxes in
respect of any transfer occurring contemporaneously with such issue).

         3.       EXERCISE OF WARRANT.

                  (a) Except as provided in Section 4 herein, exercise of the
         purchase rights represented by this Warrant may be made at any time or
         times on or after the Initial Exercise Date, and before the close of
         business on the Termination Date by the surrender of this Warrant and
         the Notice of Exercise Form annexed hereto duly executed, at the office
         of the Company (or such other office or agency of the Company as it may
         designate by notice in writing to the registered holder hereof at the
         address of such holder appearing on the books of the Company) and upon
         payment of the Exercise Price of the shares thereby purchased by wire
         transfer or cashier's check drawn on a United States bank, the holder
         of this Warrant shall be entitled to receive a certificate for the
         number of shares of Common Stock so purchased. Certificates for shares
         purchased hereunder shall be delivered to the holder hereof within
         three (3) Trading Days after the date on which this Warrant shall have
         been exercised as aforesaid. This Warrant shall be deemed to have been
         exercised and such certificate or certificates shall be deemed to have
         been issued, and Holder or any other person so designated to be named
         therein shall be deemed to have become a holder of record of such
         shares for all purposes, as of the date the Warrant has been exercised
         by payment to the Company of the Exercise Price and all taxes required
         to be paid by Holder, if any, pursuant to Section 5 prior to the
         issuance of such shares, have been paid.

                  (b) If this Warrant shall have been exercised in part, the
         Company shall, at the time of delivery of the certificate or
         certificates representing Warrant Shares, deliver to Holder a new
         Warrant evidencing the rights of Holder to purchase the unpurchased
         shares of Common Stock called for by this Warrant, which new Warrant
         shall in all other respects be identical with this Warrant.

                  (c) If no registration statement is effective permitting the
         resale of the shares of Common Stock issued upon exercise of this
         Warrant at any time commencing one year after the issuance date hereof,
         then this Warrant shall also be exercisable by means of a "cashless
         exercise" in which the holder shall be entitled to receive a
         certificate for the number of shares equal to the quotient obtained by
         dividing [(A-B) (X)] by (A), where:

(A) = the average of the high and low trading prices per share of Common Stock
on the Trading Day preceding the date of such election on the Nasdaq Stock
Market, or if the Common Stock is


                                      E-70
<PAGE>

not traded on the Nasdaq Stock Market, then the principal market in terms of
volume, and converted into US Dollars;

(B) = the Exercise Price of the Warrants; and

(X) = the number of shares issuable upon exercise of the Warrants in accordance
with the terms of this Warrant.

         4.       NO FRACTIONAL SHARES OR SCRIP. No fractional shares or scrip
representing fractional shares shall be issued upon the exercise of this
Warrant. As to any fraction of a share which Holder would otherwise be entitled
to purchase upon such exercise, the Company shall pay a cash adjustment in
respect of such final fraction in an amount equal to the Exercise Price.

         5.       CHARGES, TAXES AND EXPENSES. Issuance of certificates for
shares of Common Stock upon the exercise of this Warrant shall be made without
charge to the holder hereof for any issue or transfer tax or other incidental
expense in respect of the issuance of such certificate, all of which taxes and
expenses shall be paid by the Company, and such certificates shall be issued in
the name of the holder of this Warrant or in such name or names as may be
directed by the holder of this Warrant; provided, however, that in the event
certificates for shares of Common Stock are to be issued in a name other than
the name of the holder of this Warrant, this Warrant when surrendered for
exercise shall be accompanied by the Assignment Form attached hereto duly
executed by the holder hereof; and the Company may require, as a condition
thereto, the payment of a sum sufficient to reimburse it for any transfer tax
incidental thereto.

         6.       CLOSING OF BOOKS. The Company will not close its shareholder
books or records in any manner which prevents the timely exercise of this
Warrant.

         7.       TRANSFER, DIVISION AND COMBINATION. (a) Subject to compliance
with any applicable securities laws, transfer of this Warrant and all rights
hereunder, in whole or in part, shall be registered on the books of the Company
to be maintained for such purpose, upon surrender of this Warrant at the
principal office of the Company, together with a written assignment of this
Warrant substantially in the form attached hereto duly executed by Holder or its
agent or attorney and funds sufficient to pay any transfer taxes payable upon
the making of such transfer. Upon such surrender and, if required, such payment,
the Company shall execute and deliver a new Warrant or Warrants in the name of
the assignee or assignees and in the denomination or denominations specified in
such instrument of assignment, and shall issue to the assignor a new Warrant
evidencing the portion of this Warrant not so assigned, and this Warrant shall
promptly be cancelled. A Warrant, if properly assigned, may be exercised by a
new holder for the purchase of shares of Common Stock without having a new
Warrant issued.
                  (b) This Warrant may be divided or combined with other
Warrants upon presentation hereof at the aforesaid office of the Company,
together with a written notice specifying the names and denominations in which
new Warrants are to be issued, signed by Holder or its agent or attorney.
Subject to compliance with Section 7(a), as to any transfer which may be
involved in such division or combination, the Company shall execute and deliver
a new Warrant or Warrants in exchange for the Warrant or Warrants to be divided
or combined in accordance with such notice.


                                      E-71
<PAGE>

                  (c) The Company shall prepare, issue and deliver at its own
expense (other than transfer taxes) the new Warrant or Warrants under this
Section 7.

                  (d) The Company agrees to maintain, at its aforesaid office,
books for the registration and the registration of transfer of the Warrants.

         8.       NO RIGHTS AS SHAREHOLDER UNTIL EXERCISE. This Warrant does not
entitle the holder hereof to any voting rights or other rights as a shareholder
of the Company prior to the exercise hereof. Upon the surrender of this Warrant
and the payment of the aggregate Exercise Price, the Warrant Shares so purchased
shall be and be deemed to be issued to such holder as the record owner of such
shares as of the close of business on the later of the date of such surrender or
payment.

         9.       LOSS, THEFT, DESTRUCTION OR MUTILATION OF WARRANT. The Company
covenants that upon receipt by the Company of evidence reasonably satisfactory
to it of the loss, theft, destruction or mutilation of this Warrant certificate
or any stock certificate relating to the Warrant Shares, and in case of loss,
theft or destruction, of indemnity or security reasonably satisfactory to it
(which shall not include the posting of any bond), and upon surrender and
cancellation of such Warrant or stock certificate, if mutilated, the Company
will make and deliver a new Warrant or stock certificate of like tenor and dated
as of such cancellation, in lieu of such Warrant or stock certificate.

         10.      SATURDAYS, SUNDAYS, HOLIDAYS, ETC. If the last or appointed
day for the taking of any action or the expiration of any right required or
granted herein shall be a Saturday, Sunday or a legal holiday, then such action
may be taken or such right may be exercised on the next succeeding day not a
Saturday, Sunday or legal holiday.

         11.      ADJUSTMENTS OF EXERCISE PRICE AND NUMBER OF WARRANT SHARES.
(a) STOCK SPLITS, ETC. The number and kind of securities purchasable upon the
exercise of this Warrant and the Exercise Price shall be subject to adjustment
from time to time upon the happening of any of the following. In case the
Company shall (i) pay a dividend in shares of Common Stock or make a
distribution in shares of Common Stock to holders of its outstanding Common
Stock, (ii) subdivide its outstanding shares of Common Stock into a greater
number of shares of Common Stock, (iii) combine its outstanding shares of Common
Stock into a smaller number of shares of Common Stock or (iv) issue any shares
of its capital stock in a reclassification of the Common Stock, then the number
of Warrant Shares purchasable upon exercise of this Warrant immediately prior
thereto shall be adjusted so that the holder of this Warrant shall be entitled
to receive the kind and number of Warrant Shares or other securities of the
Company which he would have owned or have been entitled to receive had such
Warrant been exercised in advance thereof. Upon each such adjustment of the kind
and number of Warrant Shares or other securities of the Company which are
purchasable hereunder, the holder of this Warrant shall thereafter be entitled
to purchase the number of Warrant Shares or other securities resulting from such
adjustment at an Exercise Price per Warrant Share or other security obtained by
multiplying the Exercise Price in effect immediately prior to such adjustment by
the number of Warrant Shares purchasable pursuant hereto immediately prior to
such adjustment and dividing by the number of Warrant Shares or other securities
of the Company resulting from such adjustment. An adjustment made pursuant to
this paragraph shall become effective immediately after the effective date of
such event retroactive to the record date, if any, for such event.


                                      E-72
<PAGE>

                  (b) REORGANIZATION, RECLASSIFICATION, MERGER, CONSOLIDATION OR
         DISPOSITION OF ASSETS. In case the Company shall reorganize its
         capital, reclassify its capital stock, consolidate or merge with or
         into another corporation (where the Company is not the surviving
         corporation or where there is a change in or distribution with respect
         to the Common Stock of the Company), or sell, transfer or otherwise
         dispose of all or substantially all its property, assets or business to
         another corporation and, pursuant to the terms of such reorganization,
         reclassification, merger, consolidation or disposition of assets,
         shares of common stock of the successor or acquiring corporation, or
         any cash, shares of stock or other securities or property of any nature
         whatsoever (including warrants or other subscription or purchase
         rights) in addition to or in lieu of common stock of the successor or
         acquiring corporation ("Other Property"), are to be received by or
         distributed to the holders of Common Stock of the Company, then Holder
         shall have the right thereafter to receive, upon exercise of this
         Warrant, the number of shares of common stock of the successor or
         acquiring corporation or of the Company, if it is the surviving
         corporation, and Other Property receivable upon or as a result of such
         reorganization, reclassification, merger, consolidation or disposition
         of assets by a holder of the number of shares of Common Stock for which
         this Warrant is exercisable immediately prior to such event. In case of
         any such reorganization, reclassification, merger, consolidation or
         disposition of assets, the successor or acquiring corporation (if other
         than the Company) shall expressly assume the due and punctual
         observance and performance of each and every covenant and condition of
         this Warrant to be performed and observed by the Company and all the
         obligations and liabilities hereunder, subject to such modifications as
         may be deemed appropriate (as determined in good faith by resolution of
         the Board of Directors of the Company) in order to provide for
         adjustments of shares of Common Stock for which this Warrant is
         exercisable which shall be as nearly equivalent as practicable to the
         adjustments provided for in this Section 11. For purposes of this
         Section 11, "common stock of the successor or acquiring corporation"
         shall include stock of such corporation of any class which is not
         preferred as to dividends or assets over any other class of stock of
         such corporation and which is not subject to redemption and shall also
         include any evidences of indebtedness, shares of stock or other
         securities which are convertible into or exchangeable for any such
         stock, either immediately or upon the arrival of a specified date or
         the happening of a specified event and any warrants or other rights to
         subscribe for or purchase any such stock. The foregoing provisions of
         this Section 11 shall similarly apply to successive reorganizations,
         reclassifications, mergers, consolidations or disposition of assets.

         12.      VOLUNTARY ADJUSTMENT BY THE COMPANY. The Company may at any
time during the term of this Warrant, reduce the then current Exercise Price to
any amount and for any period of time deemed appropriate by the Board of
Directors of the Company.

         13.      NOTICE OF ADJUSTMENT. Whenever the number of Warrant Shares or
number or kind of securities or other property purchasable upon the exercise of
this Warrant or the Exercise Price is adjusted, as herein provided, the Company
shall promptly mail by registered or certified mail, return receipt requested,
to the holder of this Warrant notice of such adjustment or adjustments setting
forth the number of Warrant Shares (and other securities or property)
purchasable upon the exercise of this Warrant and the Exercise Price of such
Warrant Shares (and other securities or property) after such adjustment, setting
forth a brief statement of the facts requiring such adjustment and setting forth
the computation by which such adjustment was


                                      E-73
<PAGE>

made. Such notice, in the absence of manifest error, shall be conclusive
evidence of the correctness of such adjustment.

         14.      NOTICE OF CORPORATE ACTION. If at any time:

         (a)      the Company shall take a record of the holders of its Common
Stock for the purpose of entitling them to receive a dividend or other
distribution, or any right to subscribe for or purchase any evidences of its
indebtedness, any shares of stock of any class or any other securities or
property, or to receive any other right, or

         (b)      there shall be any capital reorganization of the Company, any
reclassification or recapitalization of the capital stock of the Company or any
consolidation or merger of the Company with, or any sale, transfer or other
disposition of all or substantially all the property, assets or business of the
Company to, another corporation or,

         (c) there shall be a voluntary or involuntary dissolution,
liquidation or winding up of the Company; then, in any one or more of such
cases, the Company shall give to Holder (i) at least 30 days' prior written
notice of the date on which a record date shall be selected for such dividend,
distribution or right or for determining rights to vote in respect of any such
reorganization, reclassification, merger, consolidation, sale, transfer,
disposition, liquidation or winding up, and (ii) in the case of any such
reorganization, reclassification, merger, consolidation, sale, transfer,
disposition, dissolution, liquidation or winding up, at least 30 days' prior
written notice of the date when the same shall take place. Such notice in
accordance with the foregoing clause also shall specify (i) the date on which
any such record is to be taken for the purpose of such dividend, distribution or
right, the date on which the holders of Common Stock shall be entitled to any
such dividend, distribution or right, and the amount and character thereof, and
(ii) the date on which any such reorganization, reclassification, merger,
consolidation, sale, transfer, disposition, dissolution, liquidation or winding
up is to take place and the time, if any such time is to be fixed, as of which
the holders of Common Stock shall be entitled to exchange their shares of Common
Stock for securities or other property deliverable upon such disposition,
dissolution, liquidation or winding up. Each such written notice shall be
sufficiently given if addressed to Holder at the last address of Holder
appearing on the books of the Company and delivered in accordance with Section
16(d).

         15.      AUTHORIZED SHARES. The Company covenants that during the
period the Warrant is outstanding, it will reserve from its authorized and
unissued Common Stock a sufficient number of shares to provide for the issuance
of the Warrant Shares upon the exercise of any purchase rights under this
Warrant. The Company further covenants that its issuance of this Warrant shall
constitute full authority to its officers who are charged with the duty of
executing stock certificates to execute and issue the necessary certificates for
the Warrant Shares upon the exercise of the purchase rights under this Warrant.
The Company will take all such reasonable action as may be necessary to assure
that such Warrant Shares may be issued as provided herein without violation of
any applicable law or regulation, or of any requirements of the Principal Market
upon which the Common Stock may be listed.

                  The Company shall not by any action, including, without
limitation, amending its certificate of incorporation or through any
reorganization, transfer of assets, consolidation, merger, dissolution, issue or
sale of securities or any other voluntary action, avoid


                                      E-74
<PAGE>

or seek to avoid the observance or performance of any of the terms of this
Warrant, but will at all times in good faith assist in the carrying out of all
such terms and in the taking of all such actions as may be necessary or
appropriate to protect the rights of Holder against impairment. Without limiting
the generality of the foregoing, the Company will (a) not increase the par value
of any shares of Common Stock receivable upon the exercise of this Warrant above
the amount payable therefor upon such exercise immediately prior to such
increase in par value, (b) take all such action as may be necessary or
appropriate in order that the Company may validly and legally issue fully paid
and nonassessable shares of Common Stock upon the exercise of this Warrant, and
(c) use its best efforts to obtain all such authorizations, exemptions or
consents from any public regulatory body having jurisdiction thereof as may be
necessary to enable the Company to perform its obligations under this Warrant.

                  Before taking any action which would result in an adjustment
in the number of shares of Common Stock for which this Warrant is exercisable or
in the Exercise Price, the Company shall obtain all such authorizations or
exemptions thereof, or consents thereto, as may be necessary from any public
regulatory body or bodies having jurisdiction thereof.

         16.      Miscellaneous.

                  (a) JURISDICTION. This Warrant shall be binding upon any
successors or assigns of the Company. This Warrant shall constitute a contract
under the laws of New York, without regard to its conflict of law, principles or
rules, and be subject to arbitration pursuant to the terms set forth in the
Purchase Agreement.

                  (b) RESTRICTIONS. The holder hereof acknowledges that the
Warrant Shares acquired upon the exercise of this Warrant, if not registered,
will have restrictions upon resale imposed by state and federal securities laws.

                  (c) NONWAIVER AND EXPENSES. No course of dealing or any delay
or failure to exercise any right hereunder on the part of Holder shall operate
as a waiver of such right or otherwise prejudice Holder's rights, powers or
remedies, notwithstanding all rights hereunder terminate on the Termination
Date. If the Company fails to comply with any provision of this Warrant, the
Company shall pay to Holder such amounts as shall be sufficient to cover any
costs and expenses including, but not limited to, reasonable attorneys' fees,
including those of appellate proceedings, incurred by Holder in collecting any
amounts due pursuant hereto or in otherwise enforcing any of its rights, powers
or remedies hereunder.

                  (d) NOTICES. Any notice, request or other document required or
permitted to be given or delivered to the holder hereof by the Company shall be
delivered in accordance with the notice provisions of the Purchase Agreement.

                  (e) LIMITATION OF LIABILITY. No provision hereof, in the
absence of affirmative action by Holder to purchase shares of Common Stock, and
no enumeration herein of the


                                      E-75
<PAGE>

rights or privileges of Holder hereof, shall give rise to any liability of
Holder for the purchase price of any Common Stock or as a stockholder of the
Company, whether such liability is asserted by the Company or by creditors of
the Company.

                  (f) REMEDIES. Holder, in addition to being entitled to
exercise all rights granted by law, including recovery of damages, will be
entitled to specific performance of its rights under this Warrant. The
Company agrees that monetary damages would not be adequate compensation for
any loss incurred by reason of a breach by it of the provisions of this
Warrant and hereby agrees to waive the defense in any action for specific
performance that a remedy at law would be adequate.

                  (g) SUCCESSORS AND ASSIGNS. Subject to applicable securities
laws, this Warrant and the rights and obligations evidenced hereby shall inure
to the benefit of and be binding upon the successors of the Company and the
successors and permitted assigns of Holder. The provisions of this Warrant are
intended to be for the benefit of all Holders from time to time of this Warrant
and shall be enforceable by any such Holder or holder of Warrant Shares.

                  (h) INDEMNIFICATION. The Company agrees to indemnify and hold
harmless Holder from and against any liabilities, obligations, losses, damages,
penalties, actions, judgments, suits, claims, costs, attorneys' fees, expenses
and disbursements of any kind which may be imposed upon, incurred by or asserted
against Holder in any manner relating to or arising out of any failure by the
Company to perform or observe in any material respect any of its covenants,
agreements, undertakings or obligations set forth in this Warrant; PROVIDED,
HOWEVER, that the Company will not be liable hereunder to the extent that any
liabilities, obligations, losses, damages, penalties, actions, judgments, suits,
claims, costs, attorneys' fees, expenses or disbursements are found in a final
non-appealable judgment by a court to have resulted from Holder's negligence,
bad faith or willful misconduct in its capacity as a stockholder or
warrantholder of the Company.

                  (i) AMENDMENT. This Warrant may be modified or amended or the
provisions hereof waived with the written consent of the Company and the Holder.

                  (j) SEVERABILITY. Wherever possible, each provision of this
Warrant shall be interpreted in such manner as to be effective and valid under
applicable law, but if any provision of this Warrant shall be prohibited by or
invalid under applicable law, such provision shall be ineffective to the extent
of such prohibition or invalidity, without invalidating the remainder of such
provisions or the remaining provisions of this Warrant.

                  (k) HEADINGS. The headings used in this Warrant are for the
convenience of reference only and shall not, for any purpose, be deemed a part
of this Warrant.


                                      E-76
<PAGE>

                  IN WITNESS WHEREOF, the Company has caused this Warrant to be
executed by its officer thereunto duly authorized.

Dated: March 2, 2000

                          NETLOJIX COMMUNICATIONS, INC.

                          By: /s/ MICHAEL J. USSERY
                              ---------------------
                             Michael J. Ussery, Chief Financial Officer


                                      E-77
<PAGE>

                               NOTICE OF EXERCISE

To:      NetLojix Communications, Inc.


         (1) The undersigned hereby elects to purchase ________ shares
of Common Stock (the "Common Stock"), of NetLojix Communications, Inc.
pursuant to the terms of the attached Warrant, and tenders herewith payment
of the exercise price in full, together with all applicable transfer taxes,
if any.

         (2) Please issue a certificate or certificates representing
said shares of Common Stock in the name of the undersigned or in such other
name as is specified below:


                  ----------------------------------------
                  (Name)

                  ----------------------------------------
                  (Address)

                  ----------------------------------------




Dated:

                                                 ------------------------------
                                                 Signature


                                      E-78
<PAGE>

                                 ASSIGNMENT FORM

                    (To assign the foregoing warrant, execute
                   this form and supply required information.
                 Do not use this form to exercise the warrant.)

         FOR VALUE RECEIVED, the foregoing Warrant and all rights evidenced
thereby are hereby assigned to

_______________________________________________ whose address is

_________________________________________________________________


_________________________________________________________________

                                          Dated:  ______________, _______


           Holder's Signature:   _____________________________

           Holder's Address:     _____________________________

                                 _____________________________


Signature Guaranteed:  ___________________________________________



NOTE: The signature to this Assignment Form must correspond with the name as it
appears on the face of the Warrant, without alteration or enlargement or any
change whatsoever, and must be guaranteed by a bank or trust company. Officers
of corporations and those acting in an fiduciary or other representative
capacity should file proper evidence of authority to assign the foregoing
Warrant.


                                      E-79