-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 RUsYw6TRLeJNsljKzpWz8BbA8rJ5Upd5+zy1l+4NVlLzLACtq+fnEkwi+xehEo8n
 liTjO1/NAr/ddKwzVZOX8w==

<SEC-DOCUMENT>0000919574-11-000321.txt : 20110125
<SEC-HEADER>0000919574-11-000321.hdr.sgml : 20110125
<ACCEPTANCE-DATETIME>20110125180732
ACCESSION NUMBER:		0000919574-11-000321
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20110120
FILED AS OF DATE:		20110125
DATE AS OF CHANGE:		20110125

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			AUERBACH JONATHAN A G
		CENTRAL INDEX KEY:			0001176208

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-15288
		FILM NUMBER:		11547394

	MAIL ADDRESS:	
		STREET 1:		215 E 73RD STREET
		CITY:			NEW YORK
		STATE:			NY
		ZIP:			10021

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			NETWORK 1 SECURITY SOLUTIONS INC
		CENTRAL INDEX KEY:			0001065078
		STANDARD INDUSTRIAL CLASSIFICATION:	SERVICES-PREPACKAGED SOFTWARE [7372]
		IRS NUMBER:				113027591
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		445 PARK AVENUE
		STREET 2:		SUITE 1018
		CITY:			NEW YORK
		STATE:			NY
		ZIP:			10022
		BUSINESS PHONE:		2128295770

	MAIL ADDRESS:	
		STREET 1:		445 PARK AVENUE
		STREET 2:		SUITE 1018
		CITY:			NEW YORK
		STATE:			NY
		ZIP:			10022

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Hound Partners, LLC
		CENTRAL INDEX KEY:			0001353316
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-15288
		FILM NUMBER:		11547396

	BUSINESS ADDRESS:	
		STREET 1:		101 PARK AVENUE
		STREET 2:		48TH FLOOR
		CITY:			NEW YORK
		STATE:			NY
		ZIP:			10178
		BUSINESS PHONE:		212-984-2500

	MAIL ADDRESS:	
		STREET 1:		101 PARK AVENUE
		STREET 2:		48TH FLOOR
		CITY:			NEW YORK
		STATE:			NY
		ZIP:			10178

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Hound Performance, LLC
		CENTRAL INDEX KEY:			0001375882
		STATE OF INCORPORATION:			DE

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-15288
		FILM NUMBER:		11547395

	BUSINESS ADDRESS:	
		STREET 1:		101 PARK AVENUE
		STREET 2:		48TH FLOOR
		CITY:			NEW YORK
		STATE:			NY
		ZIP:			10178
		BUSINESS PHONE:		(212) 984-2500

	MAIL ADDRESS:	
		STREET 1:		101 PARK AVENUE
		STREET 2:		48TH FLOOR
		CITY:			NEW YORK
		STATE:			NY
		ZIP:			10178
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>p1166310.xml
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2011-01-20</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001065078</issuerCik>
        <issuerName>NETWORK 1 SECURITY SOLUTIONS INC</issuerName>
        <issuerTradingSymbol>NSSI</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001353316</rptOwnerCik>
            <rptOwnerName>Hound Partners, LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>101 PARK AVENUE</rptOwnerStreet1>
            <rptOwnerStreet2>48TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10178</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001375882</rptOwnerCik>
            <rptOwnerName>Hound Performance, LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>101 PARK AVENUE</rptOwnerStreet1>
            <rptOwnerStreet2>48TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10178</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001176208</rptOwnerCik>
            <rptOwnerName>AUERBACH JONATHAN A G</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>101 PARK AVENUE</rptOwnerStreet1>
            <rptOwnerStreet2>48TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10178</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common stock $.01 par value per share</value>
            </securityTitle>
            <transactionDate>
                <value>2011-01-20</value>
            </transactionDate>
            <deemedExecutionDate>
                <value>2011-01-20</value>
            </deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>35884</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>1.60</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1488611</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Hound Partners Offshore Fund, LP</value>
                    <footnoteId id="F1"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common stock $.01 par value per share</value>
            </securityTitle>
            <transactionDate>
                <value>2011-01-20</value>
            </transactionDate>
            <deemedExecutionDate>
                <value>2011-01-20</value>
            </deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>5016</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>1.60</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>153872</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Hound Partners, LLC</value>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common stock $.01 par value per share</value>
            </securityTitle>
            <transactionDate>
                <value>2011-01-24</value>
            </transactionDate>
            <deemedExecutionDate>
                <value>2011-01-24</value>
            </deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>45052</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>1.60</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1443559</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Hound Partners Offshore Fund, LP</value>
                    <footnoteId id="F1"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common stock $.01 par value per share</value>
            </securityTitle>
            <transactionDate>
                <value>2011-01-24</value>
            </transactionDate>
            <deemedExecutionDate>
                <value>2011-01-24</value>
            </deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>6318</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>1.60</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>147554</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Hound Partners, LLC</value>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">The securities may be deemed to be beneficially owned by (a) Hound Performance, LLC, the general partner of Hound Partners Offshore Fund, LP; (b) Hound Partners, LLC, the investment manager of Hound Partners Offshore Fund, LP and (c) Jonathan Auerbach, the managing member of Hound Performance, LLC and Hound Partners, LLC.  Each Reporting Person disclaims beneficial ownership in the securities reported on this Form 4 except to the extent of his or its pecuniary interest, if any, therein, and this report shall not be deemed to be an admission that such Reporting Person is the beneficial owner of such securities for purposes of Section 16 or for any other purpose.</footnote>
        <footnote id="F2">The securities may be deemed to be beneficially owned by (a) Hound Partners, LLC; (b) a separately managed account managed by Hound Partners, LLC and (c) Jonathan Auerbach, the managing member of Hound Partners, LLC.  Each Reporting Person disclaims beneficial ownership in the securities reported on this Form 4 except to the extent of his or its pecuniary interest, if any, therein, and this report shall not be deemed to be an admission that such Reporting Person is the beneficial owner of such securities for purposes of Section 16 or for any other purpose.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Hound Partners, LLC, By: /s/ Jonathan Auerbach, Managing Member</signatureName>
        <signatureDate>2011-01-25</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Hound Performance, LLC, By: /s/ Jonathan Auerbach, Managing Member</signatureName>
        <signatureDate>2011-01-25</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Jonathan Auerbach</signatureName>
        <signatureDate>2011-01-25</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
-----END PRIVACY-ENHANCED MESSAGE-----
