Overview of services running on Port 2121 TCP.
~397 Thousand IP addresses observed from May to December 2012
To get raw lists of the data go to Download. For an explanation of what this data is and how it was obtained, see Paper.

Servicename	Product	Version	Info	OS	Devicetype	Count	Percent
ftp	Netgear broadband router or ZyXel VoIP adapter ftpd	1.0				148413	37.364
ftp	Pure-FTPd					57230	14.408
ftp	D-Link DSL-2750U ftp firmware update				WAP	36482	9.185
no match						33578	8.454
ftp	vsftpd	2.0.8 or later				13233	3.332
http						12059	3.036
ftp						11670	2.938
ftp	Microsoft ftpd			Windows		8556	2.154
http	CCProxy					7861	1.979
ssh	OpenSSH	4.3	protocol 2.0			4805	1.21
irc	Dancer ircd					4014	1.011
http	SonicWALL				firewall	3647	0.918
ftp	FileZilla ftpd	0.9.40 beta		Windows		2955	0.744
chat	AIM or ICQ server					2071	0.521
ftp	Serv-U ftpd	6.4		Windows		1832	0.461
telnet						1787	0.45
socks-proxy	CCProxy socks proxy		unauthorized			1569	0.395
telnet	Cisco IOS telnetd			IOS	switch	1557	0.392
ftp	ProFTPD	1.3.3c		Unix		1503	0.378
ftp	FileZilla ftpd	0.9.41 beta		Windows		1365	0.344
ftp-proxy	Frox ftp proxy					1356	0.341
http-proxy	EZproxy web proxy					1185	0.298
ftp	MikroTik router ftpd	5.14			router	1133	0.285
ssl	SSLv3					1095	0.276
ftp	FileZilla ftpd	0.9.37 beta		Windows		1005	0.253
ftp	vsftpd (before 2.0.8) or WU-FTPD					954	0.24
ftp	ProFTPD	1.3.4a		Unix		900	0.227
ftp	oftpd			Unix		850	0.214
ftp	DrayTek Vigor router ftpd	1.0			router	845	0.213
ftp	DrayTek Vigor 2820 ADSL router ftpd	1.0			broadband router	755	0.19
telnet	Cisco 1721 router telnetd			IOS	router	750	0.189
ftp	FileZilla ftpd	0.9.34 beta		Windows		707	0.178
ftp	ProFTPD			Unix		698	0.176
ftp	FileZilla ftpd	0.9.39 beta		Windows		690	0.174
http	AIM	1.0				606	0.153
ftp	ProFTPD	1.3.1		Unix		589	0.148
ftp	ProFTPD	1.3.3a		Unix		577	0.145
ftp	MikroTik router ftpd	3.30			router	567	0.143
ftp	ProFTPD	1.3.2e		Unix		546	0.137
ftp	ProFTPD	1.3.2c		Unix		486	0.122
ftp	FileZilla ftpd	0.9.31 beta		Windows		483	0.122
ftp	Serv-U ftpd	6.0		Windows		464	0.117
ftp	MikroTik router ftpd	5.7			router	462	0.116
ftp	Synology DiskStation NAS ftpd				storage-misc	435	0.11
ftp	MikroTik router ftpd	2.9.27			router	419	0.105
http	lighttpd	1.4.29				418	0.105
ssh	OpenSSH	5.8p1-hpn13v10	protocol 2.0			413	0.104
http	lighttpd	1.4.19				402	0.101
ftp	MikroTik router ftpd	5.18			router	369	0.093
ftp	FileZilla ftpd	0.9.33 beta		Windows		367	0.092
ftp	Microsoft ftpd	5.0		Windows		363	0.091
ftp	Serv-U ftpd	6.3		Windows		338	0.085
ftp	MikroTik router ftpd	5.11			router	312	0.079
ftp	FileZilla ftpd	0.9.36 beta		Windows		305	0.077
ftp	MikroTik router ftpd	4.17			router	300	0.076
ftp	MikroTik router ftpd	5.12			router	296	0.075
ftp	MikroTik router ftpd	4.11			router	295	0.074
ftp-proxy	CCProxy ftp proxy		unregistered	Windows		290	0.073
http-proxy	CCProxy http proxy			Windows		262	0.066
ftp	MikroTik router ftpd	5.17			router	249	0.063
ftp	ProFTPD	1.3.0		Unix		247	0.062
http	Microsoft IIS httpd	6.0		Windows		246	0.062
ftp	MikroTik router ftpd	5.15			router	246	0.062
ftp	Dreambox ftpd			Linux	media device	245	0.062
ftp	MikroTik router ftpd	5.16			router	237	0.06
ftp	Gene6 ftpd	3.10.0 build 2		Windows		235	0.059
ftp	MikroTik router ftpd	5.8			router	221	0.056
ftp	ProFTPD	1.3.3d		Unix		216	0.054
http	WangWnagSimpleServer	1.0				212	0.053
ftp	MikroTik router ftpd	5.6			router	210	0.053
ftp	MikroTik router ftpd	5.2			router	210	0.053
ftp	Dreambox ftpd		German	Linux	media device	210	0.053
ftp	MikroTik router ftpd	5.5			router	199	0.05
ftp	Serv-U ftpd	6.2		Windows		187	0.047
ftp	ProFTPD	1.3.2		Unix		187	0.047
ssh	OpenSSH	5.3	protocol 2.0			185	0.047
http	Gateway-Webs					178	0.045
ftp	ProFTPD	1.3.3g		Unix		178	0.045
ftp	ProFTPD	1.3.3e		Unix		176	0.044
http	GoAhead-Webs httpd					168	0.042
ftp	ProFTPD	1.3.3		Unix		168	0.042
ssh	OpenSSH	3.9p1	protocol 1.99			166	0.042
ftp	MikroTik router ftpd	5.9			router	164	0.041
ftp	ProFTPD	1.3.4		Unix		160	0.04
http	Microsoft HTTPAPI httpd	2.0	SSDP/UPnP	Windows		158	0.04
ftp	FileZilla ftpd	0.9.24 beta		Windows		154	0.039
http	Httpd	1.0				153	0.039
http	Avtech AVN801 network camera	1.0	UPnP 1.0		webcam	150	0.038
ftp	MikroTik router ftpd	4.16			router	142	0.036
ssh	OpenSSH	4.3	protocol 1.99			136	0.034
ftp	MikroTik router ftpd	4.10			router	136	0.034
http	Apache	2.2.3	(CentOS)			133	0.033
ftp	FileZilla ftpd	0.9.32 beta		Windows		133	0.033
http	Microsoft IIS httpd					128	0.032
ftp	MikroTik router ftpd	5.13			router	126	0.032
http	Netwave IP camera http config				webcam	109	0.027
http	Apache	2.2.3				108	0.027
ftp	ZyXEL ZXDSL 831CII ADSL modem telnetd	1.0			broadband router	107	0.027
ftp	ProFTPD	1.3.3rc4		Unix		100	0.025
http	Apache Tomcat/Coyote JSP engine	1.1				98	0.025
ftp	FreeBSD ftpd	6.00LS		FreeBSD		94	0.024
ssh			protocol 1.5			93	0.023
ftp	MikroTik router ftpd	4.5			router	90	0.023
ftp	MikroTik router ftpd	4.14			router	90	0.023
ftp	glFTPd	2.01		Linux		90	0.023
ftp	ProFTPD		requires SSL			88	0.022
ftp	ProFTPD	1.3.2b		Unix		86	0.022
ssh	OpenSSH	5.9p1-hpn13v11	protocol 2.0			84	0.021
ftp	ProFTPD	1.3.4rc2		Unix		84	0.021
ftp	ProFTPD	1.2.10		Unix		82	0.021
ftp	Serv-U ftpd	6.1		Windows		81	0.02
http	Apache	2.2.8	(Ubuntu) PHP/5.2.4-2ubuntu5.24 with Suhosin-Patch			80	0.02
ftp	MikroTik router ftpd	2.9.6			router	78	0.02
ftp	MikroTik router ftpd	5.4			router	77	0.019
ftp	NET Disk/NetStore ftpd					76	0.019
ftp	MikroTik router ftpd	3.20			router	75	0.019
http	Boa HTTPd	0.94.14rc21				73	0.018
http	Apache					71	0.018
ftp	Microsoft IIS ftpd		IP address rejected	Windows		71	0.018
ssh	OpenSSH	4.6	protocol 1.99			69	0.017
ftp	FileZilla ftpd	0.9.27 beta		Windows		68	0.017
ftp	FileZilla ftpd	0.9.23 beta		Windows		68	0.017
ftp	bftpd	1.6.6				68	0.017
ftp	FileZilla ftpd	0.9.29 beta		Windows		67	0.017
ftp	Draytek ADSL router ftpd					65	0.016
ftp	Gene6 ftpd	3.9.0 build 2		Windows		64	0.016
ftp	Gene6 ftpd	3.8.0 build 34		Windows		61	0.015
ftp	FileZilla ftpd		IP blocked	Windows		61	0.015
http	thttpd	2.24				59	0.015
ftp	Cerberus FTP Server		Personal Edition; Unregistered	Windows		59	0.015
irc-proxy	psyBNC	2.3.1				58	0.015
http	PDR-M800	1.0				58	0.015
http	FC					58	0.015
mongodb	MongoDB	39				55	0.014
ftp	ProFTPD	1.2.10rc3		Unix		55	0.014
ftp	Comtrend FTP firmware update utility					55	0.014
ftp	Balance Servers TCAdmin game hosting ftpd			Windows		55	0.014
ftp	MikroTik router ftpd	4.9			router	54	0.014
ftp	ACLogic CesarFTPd	0.99g		Windows		54	0.014
ftp	Quick 'n Easy ftpd			Windows		53	0.013
vnc	VNC		protocol 3.8			52	0.013
ssh	OpenSSH	5.1p1 Debian 5	protocol 2.0	Linux		52	0.013
ftp	MikroTik router ftpd	3.22			router	52	0.013
ftp-proxy	AVM KEN! ftp proxy					51	0.013
mongodb	MongoDB	33				49	0.012
ftp	vsftpd	2.0.4+ (ext.3)				49	0.012
mongodb	MongoDB	37				48	0.012
ftp	Serv-U ftpd	10.5		Windows		48	0.012
ftp	ProFTPD		No server available			48	0.012
telnet	Cisco router telnetd			IOS	router	47	0.012
ftp	Serv-U ftpd	8.0		Windows		47	0.012
ftp	Serv-U ftpd	5.0		Windows		46	0.012
ssh	OpenSSH	3.6.1p2	protocol 1.99			45	0.011
ftp	Serv-U ftpd	4.0		Windows		45	0.011
ftp	MikroTik router ftpd	4.13			router	45	0.011
ftp	Serv-U ftpd	5.1		Windows		42	0.011
ftp-proxy	Squid ftp proxy					41	0.01
ftp-proxy	JanaServer ftp proxy			Windows		41	0.01
arcserve	ARCserve Discovery					41	0.01
tandem-print	Sharp printer tandem printing				printer	40	0.01
ssh	OpenSSH	5.5	protocol 2.0			40	0.01
ftp	ProFTPD	1.3.3f		Unix		40	0.01
ftp	bftpd	2.2.1				40	0.01
http	uTorrent WebUI			Windows		39	0.01
http	Cross Web Server					39	0.01
ssh	OpenSSH	5.3p1 Debian 3ubuntu7	Ubuntu Linux; protocol 2.0	Linux		38	0.01
http	nginx	1.0.11				38	0.01
ftp	WinFtpd			Windows		37	0.009
ftp	MikroTik router ftpd	2.9.2			router	36	0.009
http	mini_httpd	1.19 19dec2003				35	0.009
http	Apache		SSL-only mode			35	0.009
ftp	Serv-U ftpd	11.1		Windows		35	0.009
telnet	KRASNET!					34	0.009
ssh	Dropbear sshd	0.52	protocol 2.0	Linux		34	0.009
http	Boa httpd					34	0.009
ftp	MikroTik router ftpd	3.24			router	34	0.009
ssh	OpenSSH	5.5p1 Debian 6+squeeze2	protocol 2.0	Linux		33	0.008
ssh	OpenSSH	5.5p1 Debian 6+squeeze1	protocol 2.0	Linux		33	0.008
http	dcs-lig-httpd					33	0.008
ftp	MikroTik router ftpd	3.13			router	33	0.008
ftp	MikroTik router ftpd	3.11			router	33	0.008
http	GoAhead-Webs					32	0.008
ftp	Serv-U ftpd	7.3		Windows		32	0.008
ftp	Serv-U ftpd	11.2		Windows		32	0.008
ssl	TLS	1.0				31	0.008
ssh	OpenSSH	4.2	protocol 1.99			31	0.008
ssh	OpenSSH	5.2	protocol 2.0			30	0.008
http-proxy	Squid http proxy	2.7.STABLE9				30	0.008
http	GeoVision GeoHttpServer for webcams				webcam	30	0.008
ftp	Xlight ftpd	3.6		Windows		30	0.008
ftp	TYPSoft ftpd	1.10		Windows		30	0.008
http	uc-httpd	1.0.0				29	0.007
http	GoAhead-Webs embedded httpd					29	0.007
ftp	WS FTPd	3.1.4		Windows		29	0.007
ftp	Serv-U ftpd	11.0		Windows		29	0.007
ftp	MikroTik router ftpd	3.10			router	29	0.007
ftp	IBM OS/400 FTPd			OS/400		29	0.007
nntp	INN nntpd		posting ok			28	0.007
http	Hikvision-Webs					28	0.007
ftp	ProFTPD	1.2.9		Unix		28	0.007
ssh	MikroTik RouterOS sshd		protocol 2.0	Linux	router	27	0.007
ftp	WU-FTPD	wu-2.6.2		Unix		27	0.007
ftp	Serv-U ftpd	9.3		Windows		27	0.007
ftp	MikroTik router ftpd	2.9.7			router	27	0.007
telnet	Linux telnetd			Linux		26	0.007
http	YAZ Z39.50 http interface	2.1.30				26	0.007
http	Microsoft IIS httpd	5.1		Windows		26	0.007
http	Boa HTTPd	0.94.13				26	0.007
ftp	zFTPServer			Windows		26	0.007
ftp	Xlight ftpd	3.7		Windows		26	0.007
ftp	Serv-U ftpd	10.3		Windows		26	0.007
ftp	bftpd	1.5				26	0.007
directconnect	Direct Connect P2P			Windows		26	0.007
ssh	OpenSSH	5.8	protocol 2.0			25	0.006
http	Apache	2.2.14	(Fedora)			25	0.006
ftp	Serv-U ftpd	10.4		Windows		25	0.006
ftp	pyftpdlib	0.5.2				25	0.006
ssh	OpenSSH	5.9p1 Debian 5ubuntu1	Ubuntu Linux; protocol 2.0	Linux		24	0.006
ftp	ProFTPD	1.3.3b		Unix		24	0.006
ftp	MikroTik router ftpd	4.6			router	24	0.006
ftp	MikroTik router ftpd	4.15			router	24	0.006
ftp	bftpd	1.6				24	0.006
ftp	ALFTP					24	0.006
mongodb	MongoDB	34				23	0.006
http	thttpd	2.25b				23	0.006
ftp	Serv-U ftpd	5.2		Windows		23	0.006
ftp	Serv-U ftpd	10.0		Windows		23	0.006
ftp	ProFTPD	1.3.2a		Unix		23	0.006
ftp	FileZilla ftpd	0.9.18 beta		Windows		23	0.006
http	Microsoft IIS httpd	7.0		Windows		22	0.006
ftp	vsftpd	2.0.7+ (ext.1)				22	0.006
ftp	stupid-ftpd					22	0.006
ftp	Serv-U ftpd	11.3		Windows		22	0.006
ftp	MikroTik router ftpd	3.31			router	22	0.006
ftp	Guild ftpd	0.999.14		Windows		22	0.006
ftp	AD Network Video Dedicated Micros DVR ftpd				webcam	22	0.006
ssh			protocol 2.0			21	0.005
http	Apache	2.2.15	(CentOS)			21	0.005
ftp	WS FTPd	5.0.5		Windows		21	0.005
ftp	TYPSoft ftpd	0.99.6		Windows		21	0.005
ftp-proxy	kingate ftp proxy	1.6		Windows		21	0.005
ftp	MikroTik router ftpd	5.0			router	21	0.005
mongodb	MongoDB	40				20	0.005
http	thttpd	2.24 26oct2003				20	0.005
http	Microsoft IIS httpd	7.5		Windows		20	0.005
http	HttpFileServer httpd	2.3 beta		Windows		20	0.005
ftp	vsftpd		Misconfigured	Unix		20	0.005
ftp	Sonic FTP Server	1.06a				20	0.005
ftp	Serv-U ftpd	12.0		Windows		20	0.005
ftp	Serv-U ftpd	10.2		Windows		20	0.005
ftp	Rumpus ftpd			Mac OS X		20	0.005
ftp	GNU Inetutils FTPd	1.4.1				20	0.005