<PAGE>   1


                                                                    EXHIBIT 10.6


THE SECURITIES REPRESENTED BY THIS CERTIFICATE HAVE NOT BEEN REGISTERED UNDER
THE SECURITIES ACT OF 1933, AS AMENDED. THESE SECURITIES MAY NOT BE OFFERED OR
SOLD IN THE ABSENCE OF SUCH REGISTRATION OR AN EXEMPTION FROM REGISTRATION UNDER
SUCH ACT.

                         THE TRANSFER OF THIS WARRANT IS
                         RESTRICTED AS DESCRIBED HEREIN.

                       FASTCOMM COMMUNICATIONS CORPORATION

               Warrant for the Purchase of Shares of Common Stock,
                            par value $0.01 per Share


No. KB-1                                                          200,000 Shares


              THIS CERTIFIES that, for value received, KAUFMAN BROS., L.P., 800
Third Avenue - 25th Floor, New York, New York 10022 (the "Holder"), is entitled
to subscribe for and purchase from FASTCOMM COMMUNICATIONS CORPORATION, a
Delaware corporation (the "Company"), upon the terms and conditions set forth
herein, at any time or from time to time after February 1, 2000, and before 5:00
P.M. on January 31, 2003, New York time (the "Exercise Period"), 200,000 shares
of the Company's Common Stock, par value $0.01 per share ("Common Stock"), at a
price of $7.50 per share (the "Exercise Price"). As used herein the term "this
Warrant" shall mean and include this Warrant and any Common Stock or Warrants
hereafter issued as a consequence of the exercise or transfer of this Warrant in
whole or in part. This Warrant may not be sold, transferred, assigned or
hypothecated except that it may be transferred, in whole or in part, to (i) not
more that ten officers or partners of the Holder (or the officers or partners of
any such partner); (ii) a successor to the Holder, or the officers or partners
of such successor; (iii) a purchaser of substantially all of the assets of the
Holder; or (iv) by operation of law; and the term the "Holder" as used herein
shall include any transferee to whom this Warrant has been transferred in
accordance with the above.

              The number of shares of Common Stock issuable upon exercise of the
Warrant (the "Warrant Shares") and the Exercise Price may be adjusted from time
to time as hereinafter set forth.

              1.     This Warrant may be exercised during the Exercise Period,
as to the whole or any lesser number of whole Warrant Shares, by the surrender
of this Warrant (with the election at the end hereof duly executed) to the
Company at its office at 45472 Holiday Drive, Dulles, Virginia, 20166 or at such
other place as is designated in writing by the Company, together with a
certified or bank cashier's check payable to the order of the Company in an


<PAGE>   2


amount equal to the Exercise Price multiplied by the number of Warrant Shares
for which this Warrant is being exercised (the "Stock Purchase Price").

              2.     (a)    In lieu of the payment of the Stock Purchase Price,
       the Holder shall have the right (but not the obligation), to require the
       Company to convert this Warrant, in whole or in part, into shares of
       Common Stock (the "Conversion Right") as provided for in this Section 2.
       Upon exercise of the Conversion Right, the Company shall deliver to the
       Holder (without payment by the Holder of any of the Stock Purchase Price)
       that number of shares of Common Stock (the "Conversion Shares") equal to
       the quotient obtained by dividing (x) the value of this Warrant (or
       portion thereof as to which the Conversion Right is being exercised if
       the Conversion Right is being exercised in part) at the time the
       Conversion Right is exercised (determined by subtracting the aggregate
       Stock Purchase Price of the shares of Common Stock as to which the
       Conversion Right is being exercised in effect immediately prior to the
       exercise of the Conversion Right from the aggregate Current Market Price
       (as defined in Section 6(d) hereof) of the shares of Common Stock as to
       which the Conversion Right is being exercised) by (y) the Current Market
       Price of one share of Common Stock immediately prior to the exercise of
       the Conversion Right.

                     (b)    The Conversion Right provided under this Section 2
       may be exercised in whole or in part and at any time and from time to
       time while this Warrant remains outstanding. In order to exercise the
       Conversion Right, the Holder shall surrender to the Company, at its
       offices, this Warrant with the Notice of Conversion at the end hereof
       duly executed. The presentation and surrender shall be deemed a waiver of
       the Holder's obligation to pay all or any portion of the aggregate
       purchase price payable for the shares of Common Stock as to which such
       Conversion Right is being exercised. This Warrant (or so much thereof as
       shall have been surrendered for conversion) shall be deemed to have been
       converted immediately prior to the close of business on the day of
       surrender of such Warrant for conversion in accordance with the foregoing
       provisions.

              3.     Upon each exercise of the Holder's rights to purchase
Warrant Shares or Conversion Shares, the Holder shall be deemed to be the holder
of record of the Warrant Shares or Conversion Shares issuable upon such exercise
or conversion, notwithstanding that the transfer books of the Company shall then
be closed or certificates representing such Warrant Shares or Conversion Shares
shall not then have been actually delivered to the Holder. As soon as
practicable after each such exercise or conversion of this Warrant, the Company
shall issue and deliver to the Holder a certificate or certificates for the
Warrant Shares or Conversion Shares issuable upon such exercise or conversion,
registered in the name of the Holder or its designee. If this Warrant should be
exercised or converted in part only, the Company shall, upon surrender of this
Warrant for cancellation, execute and deliver a new Warrant evidencing the right
of the Holder to purchase the balance of the Warrant Shares (or portions
thereof) subject to purchase hereunder.


<PAGE>   3


              4.     Any Warrant issued upon the transfer or exercise or
conversion in part of this Warrant shall be numbered and shall be registered in
a Warrant Register as they are issued. The Company shall be entitled to treat
the registered holder of any Warrant on the Warrant Register as the owner in
fact thereof for all purposes and shall not be bound to recognize any equitable
or other claim to or interest in such Warrant on the part of any other person,
and shall not be liable for any registration or transfer of Warrants which are
registered or to be registered in the name of a fiduciary or the nominee of a
fiduciary unless made with the actual knowledge that a fiduciary or nominee is
committing a breach of trust in requesting such registration or transfer, or
with the knowledge of such facts that its participation therein amounts to bad
faith. This Warrant shall be transferable only on the books of the Company upon
delivery thereof duly endorsed by the Holder or by his duly authorized attorney
or representative, or accompanied by proper evidence of succession, assignment,
or authority to transfer. In all cases of transfer by an attorney, executor,
administrator, guardian, or other legal representative, duly authenticated
evidence of his or its authority shall be produced. Upon any registration of
transfer, the Company shall deliver a new Warrant or Warrants to the person
entitled thereto. This Warrant may be exchanged, at the option of the Holder
thereof, for another Warrant, or other Warrants of different denominations, of
like tenor and representing in the aggregate the right to purchase a like number
of Warrant Shares (or portions thereof), upon surrender to the Company or its
duly authorized agent. Notwithstanding the foregoing, the Company shall have no
obligation to cause Warrants to be transferred on its books to any person if, in
the opinion of counsel to the Company, such transfer does not comply with
applicable law, including without limitations, the provisions of the Securities
Act of 1933, as amended (the "Act"), and the rules and regulations thereunder
and any state securities laws or regulations.

              5.     The Company shall at all times reserve and keep available
out of its authorized and unissued Common Stock, solely for the purpose of
providing for the exercise of the rights to purchase all Warrant Shares and/or
Conversion Shares granted pursuant to this Warrant, such number of shares of
Common Stock as shall, from time to time, be sufficient therefor. The Company
covenants that all shares of Common Stock issuable upon exercise of this
Warrant, upon receipt by the Company of the full Exercise Price therefor, and
all shares of Common Stock issuable upon conversion of this Warrant, shall be
validly issued, fully paid, non-assessable, and free of preemptive rights.

              6.     (a)    In case the Company shall at any time after the date
       hereof (i) declare a dividend on the outstanding shares of Common Stock
       payable solely in the shares of its capital stock, (ii) subdivide the
       outstanding Common Stock, (iii) combine the outstanding Common Stock into
       a smaller number of shares, or (iv) issue any shares of its capital stock
       by reclassification of the Common Stock (including any such
       reclassification in connection with a consolidation or merger in which
       the Company is the continuing corporation), then, in each case, the
       Exercise Price, and the number and kind of securities issuable upon
       exercise or conversion of this Warrant, in effect at the time of the
       record date for such dividend or of the effective date of such
       subdivision, combination, or reclassification, shall be proportionately
       adjusted so that the Holder after such time shall be entitled to receive
       the aggregate number and kind of shares


<PAGE>   4


       which, if such Warrant had been exercised or converted immediately prior
       to such time, he would have owned upon such exercise or conversion and
       been entitled to receive by virtue of such dividend, subdivision,
       combination, or reclassification. Such adjustment shall be made
       successively whenever any event listed above shall occur.

                     (b)    In case the Company shall issue or fix a record date
       for the issuance to all holders of Common Stock of rights, options, or
       warrants to subscribe for or purchase Common Stock (or securities
       convertible into or exchangeable for Common Stock) at a price per share
       (or having a conversion or exchange price per share, if a security
       convertible into or exchangeable for Common Stock) less than the Current
       Market Price per share of Common Stock on such record date, then, in each
       case, the Exercise Price shall be adjusted by multiplying the Exercise
       Price in effect immediately prior to such record date by a fraction, the
       numerator of which shall be the number of shares of Common Stock
       outstanding on such record date plus the number of shares of Common Stock
       which the aggregate offering price of the total number of shares of
       Common Stock so to be offered (or the aggregate initial conversion or
       exchange price of the convertible or exchangeable securities so to be
       offered) would purchase at such Current Market Price and the denominator
       of which shall be the number of shares of Common Stock outstanding on
       such record date plus the number of additional shares of Common Stock to
       be offered for subscription or purchase (or into which the convertible or
       exchangeable securities so to be offered are initially convertible or
       exchangeable). Such adjustment shall become effective at the close of
       business on such record date; provided, however, that, to the extent the
       shares of Common Stock (or securities convertible into or exchangeable
       for shares of Common Stock) are not delivered, the Exercise Price shall
       be readjusted after the expiration of such rights, options, or warrants
       (but only with respect to Warrants exercised after such expiration), to
       the Exercise Price which would then be in effect had the adjustments made
       upon the issuance of such rights, options, or warrants been made upon the
       basis of delivery of only the number of shares of Common Stock (or
       securities convertible into or exchangeable for shares of Common Stock)
       actually issued. In case any subscription price may be paid in a
       consideration part or all of which shall be in a form other than cash,
       the value of such consideration shall be as determined in good faith by
       the board of directors of the Company, whose determination shall be
       conclusive absent manifest error. Shares of Common Stock owned by or held
       for the account of the Company or any majority-owned subsidiary shall not
       be deemed outstanding for the purpose of any such computation.

                     (c)    In case the Company shall distribute to all holders
       of Common Stock (including any such distribution made to the stockholders
       of the Company in connection with a consolidation or merger in which the
       Company is the continuing corporation) evidences of its indebtedness or
       assets (other than cash dividends or distributions and dividends payable
       in shares of Common Stock), or rights, options, or warrants to subscribe
       for or purchase Common Stock, or securities convertible into or
       exchangeable for shares of Common Stock (excluding those with respect to
       the issuance


<PAGE>   5


of which an adjustment of the Exercise Price is provided pursuant to Section
6(b) hereof), then, in each case, the Exercise Price shall be adjusted by
multiplying the Exercise Price in effect immediately prior to the record date
for the determination of stockholders entitled to receive such distribution by a
fraction, the numerator of which shall be the Current Market Price per share of
Common Stock on such record date, less the fair market value (as determined in
good faith by the board of directors of the Company, whose determination shall
be conclusive absent manifest error) of the portion of the evidences of
indebtedness or assets so to be distributed, or of such rights, options, or
warrants or convertible or exchangeable securities, applicable to one share, and
the denominator of which shall be such Current Market Price per share of Common
Stock. Such adjustment shall be made whenever any such distribution is made, and
shall become effective on the record date for the determination of stockholders
entitled to receive such distribution.

              (d)    For the purpose of any computation under this Section 6,
the Current Market Price per share of Common Stock on any date shall be
deemed to be the average of the daily closing prices for the 30 consecutive
trading days immediately preceding the date in question. The closing price for
each day shall be the last reported sales price regular way or, in case no such
reported sale takes place on such day, the closing bid price regular way, in
either case on the principal national securities exchange (including, for
purposes hereof, the NASDAQ SmallCap Market) on which the Common Stock is listed
or admitted to trading or, if the Common Stock is not listed or admitted to
trading on any national securities exchange, the highest reported bid price for
the Common Stock as furnished by the National Association of Securities Dealers,
Inc. through NASDAQ or a similar organization if NASDAQ is no longer reporting
such information. If on any such date the Common Stock is not listed or admitted
to trading on any national securities exchange and is not quoted by NASDAQ or
any similar organization, the fair value of a share of Common Stock on such
date, as determined in good faith by the board of directors of the Company,
whose determination shall be conclusive absent manifest error, shall be used.

              (e)    No adjustment in the Exercise Price shall be required if
such adjustment is less than $.05; provided, however, that any adjustments which
by reason of this Section 6 are not required to be made shall be carried forward
and taken into account in any subsequent adjustment. All calculations under this
Section 6 shall be made to the nearest cent or to the nearest one-thousandth of
a share, as the case may be.

              (f)    In any case in which this Section 6 shall require that an
adjustment in the Exercise Price be made effective as of a record date for a
specified event, the Company may elect to defer, until the occurrence of such
event, issuing to the Holder, if the Holder exercised or converted this Warrant
after such record date, the shares of Common Stock, if any, issuable upon such
exercise or conversion over and above the shares of Common Stock, if any,
issuable upon such exercise or conversion on the basis of the Exercise Price in
effect prior to such adjustment; provided, however,


<PAGE>   6



that the Company shall deliver to the Holder a due bill or other appropriate
instrument evidencing the Holder's right to receive such additional shares upon
the occurrence of the event requiring such adjustment.

              (g)    Upon each adjustment of the Exercise Price as a result of
the calculations made in Sections 6(b) or 6(c) hereof, this Warrant shall
thereafter evidence the right to purchase, at the adjusted Exercise Price, that
number of shares (calculated to the nearest thousandth) obtained by dividing (i)
the product obtained by multiplying the number of shares purchasable upon
exercise of this Warrant prior to adjustment of the number of shares by the
Exercise Price in effect prior to adjustment of the Exercise Price, by (ii) the
Exercise Price in effect after such adjustment of the Exercise Price.

              (h)    Whenever there shall be an adjustment as provided in this
Section 6, the Company shall promptly cause written notice thereof to be sent by
registered mail, postage prepaid, to the Holder, at its address as it shall
appear in the Warrant Register, which notice shall be accompanied by an
officer's certificate setting forth the number of Warrant Shares purchasable
upon the exercise of this Warrant and the Exercise Price after such adjustment
and setting forth a brief statement of the facts requiring such adjustment and
the computation thereof, which officer's certificate shall be conclusive
evidence of the correctness of any such adjustment absent manifest error.

              (j)    The Company shall not be required to issue fractions of
shares of Common Stock or other capital stock of the Company upon the exercise
or conversion of this Warrant. If any fraction of a share would be issuable on
the exercise or conversion of this Warrant (or specified portions thereof), the
Company shall purchase such fraction for an amount in cash equal to the same
fraction of the Current Market Price of such share of Common Stock on the date
of exercise or conversion of this Warrant.

       7.     (a)    In case of any consolidation with or merger of the Company
with or into another corporation (other than a merger or consolidation in which
the Company is the surviving or continuing corporation), or in case of any sale,
lease, or conveyance to another corporation of the property and assets of any
nature of the Company as an entirety or substantially as an entirety, such
successor, leasing, or purchasing corporation, as the case may be, shall (i)
execute with the Holder an agreement providing that the Holder shall have the
right thereafter to receive upon exercise or conversion of this Warrant solely
the kind and amount of shares of stock and other securities, property, cash, or
any combination thereof receivable upon such consolidation, merger, sale, lease,
or conveyance by a holder of the number of shares of Common Stock for which this
Warrant might have been exercised or converted immediately prior to such
consolidation, merger, sale, lease, or conveyance, and (ii) make effective
provision in its certificate of incorporation or otherwise, if necessary, to
effect such agreement. Such agreement shall provide for adjustments which shall
be as nearly equivalent as practicable to the adjustments in Section 6.


<PAGE>   7




              (b)    In case of any reclassification or change of the shares of
Common Stock issuable upon exercise or conversion of this Warrant (other than a
change in par value or from no par value to a specified par value, or as a
result of a subdivision or combination, but including any change in the shares
into two or more classes or series of shares), or in case of any consolidation
or merger of another corporation into the Company in which the Company is the
continuing corporation and in which there is a reclassification or change
(including a change to the right to receive cash or other property) of the
shares of Common Stock (other than a change in par value, or from no par value
to a specified par value, or as a result of a subdivision or combination, but
including any change in the shares into two or more classes or series of
shares), the Holder shall have the right thereafter to receive upon exercise or
conversion of this Warrant solely the kind and amount of shares of stock and
other securities, property, cash, or any combination thereof receivable upon
such reclassification, change, consolidation, or merger by a holder of the
number of shares of Common Stock for which this Warrant might have been
exercised or converted immediately prior to such reclassification, change,
consolidation, or merger. Thereafter, appropriate provision shall be made for
adjustments which shall be as nearly equivalent as practicable to the
adjustments in Section 6.

              (c)    The above provisions of this Section 7 shall similarly
apply to successive reclassifications and changes of shares of Common Stock and
to successive consolidations, mergers, sales, leases, or conveyances.

       8.     In case at any time the Company shall propose

              (a)    to pay any dividend or make any distribution on shares of
Common Stock in shares of Common Stock or make any other distribution (other
than regularly scheduled cash dividends which are not in a greater amount per
share than the most recent such cash dividend) to all holders of Common Stock;
or

              (b)    to issue any rights, warrants, or other securities to all
holders of Common Stock entitling them to purchase any additional shares of
Common Stock or any other rights, warrants, or other securities; or

              (c)    to effect any reclassification or change of outstanding
shares of Common Stock, or any consolidation, merger, sale, lease, or conveyance
of property, described in Section 7; or

              (d)    to effect any liquidation, dissolution, or winding-up of
the Company; or

              (e)    to take any other action which would cause an adjustment to
the Exercise Price;


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then, and in any one or more of such cases, the Company shall give written
notice thereof, by registered mail, postage prepaid, to the Holder at the
Holder's address as it shall appear in the Warrant Register, mailed at least 15
days prior to (i) the date as of which the holders of record of shares of Common
Stock to be entitled to receive any such dividend, distribution, rights,
warrants, or other securities are to be determined, (ii) the date on which any
such reclassification, change of outstanding shares of Common Stock,
consolidation, merger, sale, lease, conveyance of property, liquidation,
dissolution, or winding-up is expected to become effective, and the date as of
which it is expected that holders of record of shares of Common Stock shall be
entitled to exchange their shares for securities or other property, if any,
deliverable upon such reclassification, change of outstanding shares,
consolidation, merger, sale, lease, conveyance of property, liquidation,
dissolution, or winding-up, or (iii) the date of such action which would require
an adjustment to the Exercise Price.

              9.     The issuance of any shares or other securities upon the
exercise or conversion of this Warrant, and the delivery of certificates or
other instruments representing such shares or other securities, shall be made
without charge to the Holder for any tax or other charge in respect of such
issuance. The Company shall not, however, be required to pay any tax which may
be payable in respect of any transfer involved in the issue and delivery of any
certificate in a name other than that of the Holder and the Company shall not be
required to issue or deliver any such certificate unless and until the person or
persons requesting the issue thereof shall have paid to the Company the amount
of such tax or shall have established to the satisfaction of the Company that
such tax has been paid.

              10.   (a)     If, at any time prior to February 1, 2003, while any
       Warrant or Warrant Shares are outstanding, the Company shall file a
       registration statement with the Securities and Exchange Commission (the
       "Commission") to register the sale any of its equity securities for its
       own account (and not for the account of a security holder or holders) for
       cash, other than (w) a registration relating to employee benefit plans,
       (x) a registration relating to a corporate reorganization or other
       transaction under Rule 145, (y) a registration relating to the Company's
       equity line of credit with Cambois Finance, Inc., or (z) a registration
       on any registration form that does not permit secondary sales, the
       Company shall give the Holder at least 15 days prior written notice of
       the filing of such registration statement. If requested by the Holder in
       writing within 10 days after receipt of any such notice, the Company
       shall, at the Company's sole expense (other than the fees and
       disbursements of counsel for the Holder and the underwriting discounts,
       if any, payable in respect of the Warrant Shares sold by the Holder),
       register or qualify all or, at the Holders' option, any portion of the
       Warrant Shares of the Holder concurrently with the registration of such
       other securities, all to the extent requisite to permit the public
       offering and sale of the Warrant Shares through the facilities of all
       appropriate securities exchanges and the over-the-counter market. As a
       condition to the registration of any Warrant Shares in an underwritten
       public offering, the Holder shall (together with the Company and the
       other holders of securities of the Company with registration rights to
       participate therein distributing their securities through such


<PAGE>   9


underwriting) enter into an underwriting agreement in customary form with the
representative of the underwriter or underwriters selected by the Company.
Notwithstanding the foregoing, if the representative of the underwriter or
underwriters of any such offering shall advise the Company in writing that, in
its opinion, the distribution of all or a portion of the Warrant Shares
requested to be included in the registration concurrently with the securities
being registered by the Company would adversely affect the distribution of such
securities by the Company for its own account, the number of shares that may be
included in such registration in such offering shall be allocated as follows:
(i) first, the Company shall be permitted to include all shares of capital stock
to be registered thereby and (ii) second, the Holder shall be allowed to include
such additional amount as the lead managing underwriter deems appropriate, such
amount to be allocated among such Holder and any other selling stockholders on a
pro rata basis based on the total number of shares of capital stock held
thereby. As used herein, "Warrant Shares" shall mean the Warrant Shares and the
Conversion Shares which, in each case, have not been previously sold pursuant to
a registration statement or Rule 144 promulgated under the Act.

              (b)    In the event of a registration pursuant to the provisions
of this Section 10, the Company shall use its best efforts to cause the Warrant
Shares so registered to be registered or qualified for sale under the securities
or blue sky laws of such jurisdictions as the Holder may reasonably request;
provided, however, that the Company shall not be required to qualify to do
business in any state by reason of this Section 10(b) in which it is not
otherwise required to qualify to do business.

              (c)    The Company shall keep effective any registration or
qualification contemplated by this Section 10 and shall from time to time amend
or supplement each applicable registration statement, preliminary prospectus,
final prospectus, application, document, and communication for such period of
time as shall be required to permit the Holder to complete the offer and sale of
the Warrant Shares covered thereby. The Company shall in no event be required to
keep any such registration or qualification in effect for a period in excess of
90 days from the date on which the Holder is first free to sell such Warrant
Shares; provided, however, that, if the Company is required to keep any such
registration or qualification in effect with respect to securities other than
the Warrant Shares beyond such period, the Company shall keep such registration
or qualification in effect as it relates to the Warrant Shares for so long as
such registration or qualification remains or is required to remain in effect in
respect of such other securities.

              (d)    In the event of a registration pursuant to the provisions
of this Section 10, the Company shall furnish to the Holder such number of
copies of the registration statement and of each amendment and supplement
thereto (in each case, including all exhibits), such reasonable number of copies
of each prospectus contained in such registration statement and each supplement
or amendment thereto (including each preliminary prospectus), all of which shall
conform to the requirements of the Act


<PAGE>   10


and the rules and regulations thereunder, and such other documents, as the
Holder may reasonably request to facilitate the disposition of the Warrant
Shares included in such registration.

              (e)    In the event of a registration pursuant to the provisions
of this Section 10, the Company shall furnish the Holder so registered with an
opinion of its counsel covering such matters as are customarily the subject of
opinions of issuer's counsel provided to underwriters in underwritten public
offerings.

              (f)    The Company agrees that until the Warrant has expired or
all of the Warrant Shares have been sold under a registration statement or
pursuant to Rule 144 under the Act, it shall keep current in filing all reports,
statements and other materials required to be filed with the Commission to
permit the Holder to sell the Warrant Shares under Rule 144.

       11.    (a)    Subject to the conditions set forth below, the Company
agrees to indemnify and hold harmless the Holder, its officers, directors,
partners, employees, agents, and counsel, and each person, if any, who controls
any such person within the meaning of Section 15 of the Act or Section 20(a) of
the Securities Exchange Act of 1934, as amended (the "Exchange Act"), from and
against any and all loss, liability, charge, claim, damage, and expense
whatsoever (which shall include, for all purposes of this Section 11, but not be
limited to, attorneys' fees and any and all reasonable expense whatsoever
incurred in investigating, preparing, or defending against any litigation,
commenced or threatened, or any claim whatsoever, and any and all amounts paid
in settlement of any claim or litigation), as and when incurred, arising out of,
based upon, or in connection with (i) any untrue statement or alleged untrue
statement of a material fact contained (A) in any registration statement,
preliminary prospectus, or final prospectus (as from time to time amended and
supplemented), or any amendment or supplement thereto, relating to the sale of
the Warrant Shares, or (B) in any application or other document or communication
(in this Section 11 collectively called an "application") executed by or on
behalf of the Company or based upon written information furnished by or on
behalf of the Company filed in any jurisdiction in order to register or qualify
any of the Warrant Shares under the securities or blue sky laws thereof or filed
with the Commission or any securities exchange; or any omission or alleged
omission to state a material fact required to be stated therein or necessary to
make the statements therein not misleading, unless such statement or omission
was made in reliance upon and in conformity with written information furnished
to the Company with respect to the Holder by or on behalf of the Holder
expressly for inclusion in any registration statement, preliminary prospectus,
or final prospectus, or any amendment or supplement thereto, or in any
application, as the case may be, or (ii) any breach of any representation,
warranty, covenant, or agreement of the Company contained in this Warrant. The
foregoing agreement to indemnify shall be in addition to any liability the
Company may otherwise have, including liabilities arising under this Warrant.


<PAGE>   11



       If any action is brought against the Holder or any of its officers,
directors, partners, employees, agents, or counsel, or any controlling persons
of such person (an "indemnified party") in respect of which indemnity may be
sought against the Company pursuant to the foregoing paragraph, such indemnified
party or parties shall promptly notify the Company in writing of the institution
of such action (but the failure so to notify shall not relieve the Company from
any liability pursuant to this Section 11(a) except to the extent that such
failure shall result in prejudice to the Company) and the Company shall promptly
assume the defense of such action, including the employment of counsel
(reasonably satisfactory to such indemnified party or parties) and payment of
expenses. Such indemnified party or parties shall have the right to employ its
or their own counsel in any such case, but the fees and expenses of such counsel
shall be at the expense of such indemnified party or parties unless the
employment of such counsel shall have been authorized in writing by the Company
in connection with the defense of such action or the Company shall not have
promptly employed counsel reasonably satisfactory to such indemnified party or
parties to have charge of the defense of such action or such indemnified party
or parties shall have reasonably concluded that there may be one or more legal
defenses available to it or them or to other indemnified parties which are
different from or additional to those available to the Company, in any of which
events such fees and expenses shall be borne by the Company and the Company
shall not have the right to direct the defense of such action on behalf of the
indemnified party or parties. The Company shall not be obligated to pay the fees
and expenses of more than one such separate counsel for any one such action or
proceeding in any one jurisdiction. Anything in this Section 11 to the contrary
notwithstanding, the Company shall not be liable for any settlement of any such
claim or action effected without its written consent, which shall not be
unreasonably withheld. The Company shall not, without the prior written consent
of each indemnified party that is not released as described in this sentence,
settle or compromise any action, or permit a default or consent to the entry of
judgment in or otherwise seek to terminate any pending or threatened action, in
respect of which indemnity may be sought hereunder (whether or not any
indemnified party is a party thereto), unless such settlement, compromise,
consent, or termination includes an unconditional release of each indemnified
party from all liability in respect of such action. The Company agrees promptly
to notify the Holder of the commencement of any litigation or proceedings
against the Company or any of its officers or directors in connection with the
sale of any Warrant Shares or any preliminary prospectus, prospectus,
registration statement, or amendment or supplement thereto, or any application
relating to any sale of any Warrant Shares.

              (b)    The Holder agrees to indemnify and hold harmless the
Company, each director of the Company, each officer of the Company who shall
have signed any registration statement covering Warrant Shares held by the
Holder, each other person, if any, who controls the Company within the meaning
of Section 15 of the Act or Section 20(a) of the Exchange Act, and its or their
respective counsel, to the same extent as the foregoing indemnity from the
Company to the Holder in Section 11(a), but only with


<PAGE>   12


respect to statements or omissions, if any, made in any registration statement,
preliminary prospectus, or final prospectus (as from time to time amended and
supplemented), or any amendment or supplement thereto, or in any application, in
reliance upon and in conformity with written information furnished to the
Company by or on behalf of the Holder expressly for inclusion in any such
registration statement, preliminary prospectus, or final prospectus, or any
amendment or supplement thereto, or in any application, as the case may be. If
any action shall be brought against the Company or any other person so
indemnified based on any such registration statement, preliminary prospectus, or
final prospectus, or any amendment or supplement thereto, or in any application,
and in respect of which indemnity may be sought against the Holder pursuant to
this Section 11(b), the Holder shall have the rights and duties given to the
Company, and the Company and each other person so indemnified shall have the
rights and duties given to the indemnified parties, by the provisions of Section
11(a).

              (c)    To provide for just and equitable contribution, if (i) an
indemnified party makes a claim for indemnification pursuant to Section 11(a) or
11(b) (subject to the limitations thereof) but it is found in a final judicial
determination, not subject to further appeal, that such indemnification may not
be enforced in such case, even though this Agreement expressly provides for
indemnification in such case, or (ii) any indemnified or indemnifying party
seeks contribution under the Act, the Exchange Act or otherwise, then the
Company (including for this purpose any contribution made by or on behalf of any
director of the Company, any officer of the Company who signed any such
registration statement, any controlling person of the Company, and its or their
respective counsel), as one entity, and the Holder (including for this purpose
any contribution by or on behalf of an indemnified party), as a second entity,
shall contribute to the losses, liabilities, claims, damages, and expenses
whatsoever to which any of them may be subject, on the basis of relevant
equitable considerations such as the relative fault of the Company and such
Holder in connection with the facts which resulted in such losses, liabilities,
claims, damages, and expenses. The relative fault, in the case of an untrue
statement, alleged untrue statement, omission, or alleged omission, shall be
determined by, among other things, whether such statement, alleged statement,
omission, or alleged omission relates to information supplied by the Company or
by such Holder, and the parties' relative intent, knowledge, access to
information, and opportunity to correct or prevent such statement, alleged
statement, omission, or alleged omission. The Company and the Holder agree that
it would be unjust and inequitable if the respective obligations of the Company
and the Holder for contribution were determined by pro rata or per capita
allocation of the aggregate losses, liabilities, claims, damages, and expenses
(even if the Holder and the other indemnified parties were treated as one entity
for such purpose) or by any other method of allocation that does not reflect the
equitable considerations referred to in this Section 11(c). In no case shall the
Holder be responsible for a portion of the contribution obligation imposed on it
in excess of its pro rata share based on the number of shares of Common Stock
owned (or which would be owned upon exercise of all Warrant or Warrant Shares)
by it and included in such registration as compared to the total number of
shares of Common

<PAGE>   13


       Stock included in such registration. No person guilty of a fraudulent
       misrepresentation (within the meaning of Section 11(f) of the Act) shall
       be entitled to contribution from any person who is not guilty of such
       fraudulent misrepresentation. For purposes of this Section 11(c), each
       person, if any, who controls the Holder within the meaning of Section 15
       of the Act or Section 20(a) of the Exchange Act and each officer,
       director, partner, employee, agent, and counsel of each such Holder or
       control person shall have the same rights to contribution as such Holder
       or control person and each person, if any, who controls the Company
       within the meaning of Section 15 of the Act or Section 20(a) of the
       Exchange Act, each officer of the Company who shall have signed any such
       registration statement, each director of the Company, and its or their
       respective counsel shall have the same rights to contribution as the
       Company, subject in each case to the provisions of this Section 11(c).
       Anything in this Section 11(c) to the contrary notwithstanding, no party
       shall be liable for contribution with respect to the settlement of any
       claim or action effected without its written consent. This Section 11(c)
       is intended to supersede any right to contribution under the Act, the
       Exchange Act or otherwise.

              12.    Unless registered pursuant to the provisions of Section 10
hereof, the Warrant Shares or Conversion Shares issued upon exercise or
conversion of the Warrants shall be subject to a stop transfer order and the
certificate or certificates evidencing such Warrant Shares shall bear the
following legend:

       "THE SECURITIES HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933
       OR QUALIFIED UNDER THE SECURITIES LAWS OF ANY STATE. THESE SECURITIES
       CANNOT BE SOLD OR TRANSFERRED WITHOUT SUCH REGISTRATION AND QUALIFICATION
       UNLESS AN EXEMPTION FROM SUCH REGISTRATION AND QUALIFICATION IS AVAILABLE
       AND THE COMPANY HAS RECEIVED AN OPINION OF COUNSEL SATISFACTORY TO THE
       COMPANY TO THAT EFFECT."

              13.    Upon receipt of evidence satisfactory to the Company of the
loss, theft, destruction, or mutilation of this Warrant (and upon surrender of
this Warrant if mutilated), and upon reimbursement of the Company's reasonable
incidental expenses, the Company shall execute and deliver to the Holder thereof
a new Warrant of like date, tenor, and denomination.

              14.    The Holder shall not have, solely on account of such
status, any rights of a stockholder of the Company, either at law or in equity,
or to any notice of meetings of stockholders or of any other proceedings of the
Company, except as provided in this Warrant.

              15.    This Warrant shall be construed in accordance with the laws
of the State of New York applicable to contracts made and performed within such
State, without regard to principles of conflicts of law.


<PAGE>   14




              16.    The Company irrevocably consents to the jurisdiction of the
courts of the federal courts located in the City of New York in connection with
any action or proceeding arising out of or relating to this Warrant, any
document or instrument delivered pursuant to, in connection with or
simultaneously with this Warrant, or a breach of this Warrant or any such
document or instrument. In any such action or proceeding, the Company waives
personal service of any summons, complaint or other process and agrees that
service thereof may be made by registered mail, return receipt requested. Within
30 days after such service, or such other time as may be mutually agreed upon in
writing by the attorneys for the parties to such action or proceeding, the
Company shall appear to answer such summons, complaint or other process. Should
the Company so served fail to appear or answer within such 30-day period or such
extended period, as the case may be, the Company shall be deemed in default and
judgment may be entered against the Company for the amount as demanded in any
summons, complaint or other process so served. The Company and Holder (by
Holder's acceptance of this Warrant) agree that if any action or proceeding is
brought to construe or enforce the terms and conditions of this Warrant or the
rights of the parties hereunder, the losing party shall pay to the prevailing
party all court costs and reasonable attorneys' fees and costs (at the
prevailing party's attorneys then-current rates) incurred in such action or
proceeding. A party that voluntarily dismisses an action or proceeding shall be
considered a losing party for purposes of this provision.



Dated: January 31, 2000



                         FASTCOMM COMMUNICATIONS CORPORATION





                         By:
                            ----------------------------------------------
                            Peter C. Madsen, Chairman & Chief Executive Officer


<PAGE>   15




                               FORM OF ASSIGNMENT


(To be executed by the registered holder if such holder is permitted to transfer
the attached Warrant.)

              FOR VALUE RECEIVED, _________________ hereby sells, assigns, and
transfers unto __________________ a Warrant to purchase __________ shares of
Common Stock, par value $.01 per share, of FastComm Communications Corporation
(the "Company"), together with all right, title, and interest therein, and does
hereby irrevocably constitute and appoint _______________________ attorney to
transfer such Warrant on the books of the Company, with full power of
substitution.


                                     Dated:
                                           -------------------------


                                     By:
                                        -----------------------------------
                                        Signature

       The signature on the foregoing Assignment must correspond to the name as
written upon the face of this Warrant in every particular, without alteration or
enlargement or any change whatsoever.


<PAGE>   16


To: FastComm Communications Corporation


                              ELECTION TO EXERCISE

       The undersigned hereby exercises his or its rights to purchase _______
Warrant Shares covered by the within Warrant and tenders payment herewith in the
amount of $_________ in accordance with the terms thereof, and requests that
certificates for such securities be issued in the name of, and delivered to:



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

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

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

(Print Name, Address and Social Security
or Tax Identification Number)

and, if such number of Warrant Shares shall not be all the Warrant Shares
covered by the within Warrant, that a new Warrant for the balance of the Warrant
Shares covered by the within Warrant be registered in the name of, and delivered
to, the undersigned at the address stated below.



                                     Dated:
                                           ------------------------

                                     By:
                                        ---------------------------------
                                        Print Name




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



Address:


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

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

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


<PAGE>   17


To:  FastComm Communications Corporation



                             CASHLESS EXERCISE FORM
            (To be executed upon conversion of the attached Warrant)


       The undersigned hereby irrevocably elects to surrender its Warrant for
the number of shares of Common Stock as shall be issuable pursuant to the
cashless exercise provisions of the within Warrant, in respect of __________
shares of Common Stock underlying the within Warrant, and requests that
certificates for such securities be issued in the name of and delivered to:


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

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

--------------------------------------------------------------------------------
                    (Print Name, Address and Social Security
                          or Tax Identification Number)

and, if such number of shares shall not be all the shares exchangeable or
purchasable under the within Warrant, that a new Warrant for the balance of the
Warrant Shares covered by the within Warrant be registered in the name of, and
delivered to, the undersigned at the address stated below.


Dated:                                      Name
      ----------------------------               -------------------------------
                                                               (Print)

Address:
        ----------------------------------------------------------------



                                            ------------------------------------
                                                 (Signature)