我们不仅可以通过相应工具识别目标主机上的服务指纹信息，还可以进行系统指纹信息识别。常见的系统指纹信息有操作系统类型、系统版本和内核版本等。本文介绍系统识别的方法。
1.Nmap系统识别
在Nmap工具中，提供了一些选项可以用来实施系统识别。下面介绍具体的实现方法。
（1）识别操作系统
在Nmap工具中提供了一个-O选项，可以用来识别操作系统。用于识别操作系统的语法格式如下：
nmap-O[host]
其中，-O选项用于识别操作系统类型。注意，这里的选项-O是大写字母O，不是0。
识别目标主机192.168.33.152的操作系统类型。执行命令如下：
root@daxueba:~#nmap-O192.168.33.152
StartingNmap7.70(https://nmap.org)at2021-08-0215:22CST
Nmapscanreportfor192.168.33.152(192.168.33.152)
Hostisup(0.00036slatency).
Notshown:997closedports
PORTSTATESERVICE
21/tcpopenftp
22/tcpopenssh
80/tcpopenhttp
MACAddress:00:0C:29:FD:58:4B(VMware)#MAC地址
Devicetype:generalpurpose#设备类型
Running:Linux3.X|4.X#运行的系统
OSCPE:cpe:/o:linux:linux_kernel:3cpe:/o:linux:linux_kernel:4#操作系统中央处理单元
OSdetails:Linux3.2-4.9#操作系统详细信息
NetworkDistance:1hop#网络距离，即从源到目标经过的网络节点
OSdetectionperformed.Pleasereportanyincorrectresultsathttps://nmap.
org/submit/.
Nmapdone:1IPaddress(1hostup)scannedin1.86seconds
从以上输出信息中可以看到，目标主机的操作系统类型为Linux，内核版本为3.2。如果Nmap不能够判断出目标操作系统的话，将会提供指纹信息给Nmap的系统数据库。例如，识别目标主机10.10.1.11的操作系统。执行命令如下：
root@daxueba:~#nmap-O10.10.1.11
StartingNmap7.70(https://nmap.org)at2021-08-0215:29CST
……
NoexactOSmatchesforhost(IfyouknowwhatOSisrunningonit,seehttp://nmap.org/submit/).
TCP/IPfingerprint:
OS:SCAN(V=5.00%D=12/16%OT=3001%CT=1%CU=32781%PV=Y%DS=1%G=Y%M=00204A%TM=4B29
OS:4048%P=i686-pc-windows-windows)SEQ(CI=I%II=I%TS=U)OPS(O1=M400%O2=%O3=%O4
OS:=%O5=%O6=)OPS(O1=M400%O2=M400%O3=%O4=%O5=%O6=)OPS(O1=%O2=M400%O3=M400%O4
OS:=%O5=%O6=)OPS(O1=%O2=%O3=M400%O4=%O5=%O6=)OPS(O1=M400%O2=%O3=M400%O4=%O5
OS:=%O6=)WIN(W1=7FF%W2=0%W3=0%W4=0%W5=0%W6=0)WIN(W1=7FF%W2=7FF%W3=0%W4=0%W5
OS:=0%W6=0)WIN(W1=0%W2=7FF%W3=7FF%W4=0%W5=0%W6=0)WIN(W1=0%W2=0%W3=7FF%W4=0%
OS:W5=0%W6=0)WIN(W1=7FF%W2=0%W3=7FF%W4=0%W5=0%W6=0)ECN(R=Y%DF=Y%T=40%W=0%O=
OS:%CC=N%Q=)T1(R=Y%DF=Y%T=40%S=O%A=S+%F=AS%RD=0%Q=)T1(R=Y%DF=Y%T=40%S=O%A=O
OS:%F=AS%RD=0%Q=)T1(R=Y%DF=Y%T=40%S=Z%A=S+%F=AR%RD=0%Q=)T2(R=Y%DF=Y%T=40%W=
OS:0%S=Z%A=S+%F=AR%O=%RD=0%Q=)T3(R=Y%DF=Y%T=40%W=0%S=Z%A=S+%F=AR%O=%RD=0%Q=
OS:)T4(R=Y%DF=Y%T=40%W=0%S=A%A=Z%F=R%O=%RD=0%Q=)T5(R=Y%DF=Y%T=40%W=0%S=Z%A=
OS:S+%F=AR%O=%RD=0%Q=)T6(R=Y%DF=Y%T=40%W=0%S=A%A=Z%F=R%O=%RD=0%Q=)T7(R=Y%DF
OS:=Y%T=40%W=0%S=Z%A=S+%F=AR%O=%RD=0%Q=)U1(R=Y%DF=Y%T=40%IPL=38%UN=0%RIPL=G
OS:%RID=G%RIPCK=G%RUCK=G%RUD=G)IE(R=Y%DFI=S%T=40%CD=S)
以上输出信息就是Nmap向数据库提交的指纹信息，这些指纹信息是自动生成的，并且标识了目标系统的操作系统。
（2）指定识别的操作系统
当扫描多个主机时，可以使用--osscan-limit选项来指定识别特定主机的操作系统类型。这样，使用该选项进行操作系统识别可以节约大量的时间。指定识别主机的操作系统类型语法格式如下：
nmap-O--osscan-limit[host]
其中，--osscan-limit选项表示针对指定的目标进行操作系统检测。如果发现一个打开和关闭的TCP端口时，操作系统检测会更有效。使用该选项，Nmap只对满足这个条件的主机进行操作系统检测。这样可以节约时间，特别是在使用-P0扫描多个主机时。该选项仅在使用-O或-A进行操作系统检测时起作用。
使用Nmap针对指定的目标进行操作系统检测。执行命令如下：
root@daxueba:~#nmap-P0192.168.1.0/24-O--osscan-limit
StartingNmap7.70(https://nmap.org)at2021-08-0216:02CST
Nmapscanreportfor192.168.1.1(192.168.1.1)
Hostisup(0.00073slatency).
Notshown:994closedports
PORTSTATESERVICE
21/tcpopenftp
80/tcpopenhttp
445/tcpopenmicrosoft-ds
5678/tcpopenrrac
8080/tcpopenhttp-proxy
52869/tcpopenunknown
MACAddress:70:85:40:53:E0:35(Unknown)
Devicetype:generalpurpose
Running:Linux3.X|4.X
OSCPE:cpe:/o:linux:linux_kernel:3cpe:/o:linux:linux_kernel:4
OSdetails:Linux3.2-4.9#操作系统详细信息
NetworkDistance:1hop
Nmapscanreportforkdkdahjd61y369j(192.168.1.3)
Hostisup(0.000085slatency).
All1000scannedportsonkdkdahjd61y369j(192.168.1.3)arefiltered
MACAddress:1C:6F:65:C8:4C:89(Giga-byteTechnology)
Nmapscanreportfortest-pc(192.168.1.5)
Hostisup(0.00047slatency).
Notshown:982closedports
PORTSTATESERVICE
21/tcpopenftp
22/tcpopenssh
80/tcpopenhttp
135/tcpopenmsrpc
139/tcpopennetbios-ssn
443/tcpopenhttps
445/tcpopenmicrosoft-ds
902/tcpopeniss-realsecure
912/tcpopenapex-mesh
1433/tcpopenms-sql-s
2383/tcpopenms-olap4
5357/tcpopenwsdapi
49152/tcpopenunknown
49153/tcpopenunknown
49154/tcpopenunknown
49155/tcpopenunknown
49157/tcpopenunknown
49158/tcpopenunknown
MACAddress:00:0C:29:21:8C:96(VMware)
Devicetype:generalpurpose
Running:MicrosoftWindows7|2008|8.1
OSCPE:cpe:/o:microsoft:windows_7::-cpe:/o:microsoft:windows_7::sp1
cpe:/o:microsoft:windows_server_2008::sp1cpe:/o:microsoft:windows_server_
2008:r2cpe:/o:microsoft:windows_8cpe:/o:microsoft:windows_8.1
OSdetails:MicrosoftWindows7SP0-SP1,WindowsServer2008SP1,Windows
Server2008R2,Windows8,orWindows8.1Update1#操作系统详细信息
NetworkDistance:1hop
Nmapscanreportfor192.168.1.6(192.168.1.6)
Hostisup(0.00057slatency).
Notshown:977closedports
PORTSTATESERVICE
21/tcpopenftp
22/tcpopenssh
23/tcpopentelnet
25/tcpopensmtp
53/tcpopendomain
80/tcpopenhttp
111/tcpopenrpcbind
139/tcpopennetbios-ssn
445/tcpopenmicrosoft-ds
512/tcpopenexec
513/tcpopenlogin
514/tcpopenshell
1099/tcpopenrmiregistry
1524/tcpopeningreslock
2049/tcpopennfs
2121/tcpopenccproxy-ftp
3306/tcpopenmysql
5432/tcpopenpostgresql
5900/tcpopenvnc
6000/tcpopenX11
6667/tcpopenirc
8009/tcpopenajp13
8180/tcpopenunknown
MACAddress:00:0C:29:3E:84:91(VMware)
Devicetype:generalpurpose
Running:Linux2.6.X
OSCPE:cpe:/o:linux:linux_kernel:2.6
OSdetails:Linux2.6.9-2.6.33#操作系统详细信息
NetworkDistance:1hop
Nmapscanreportforkali(192.168.1.9)
Hostisup(0.00093slatency).
All1000scannedportsonkali(192.168.1.9)areclosed
MACAddress:00:0C:29:6C:C4:92(VMware)
Nmapscanreportfordaxueba(192.168.1.4)
Hostisup(0.000010slatency).
All1000scannedportsondaxueba(192.168.1.4)areclosed
OSdetectionperformed.Pleasereportanyincorrectresultsat
https://nmap.org/submit/.
Nmapdone:256IPaddresses(6hostsup)scannedin7.64seconds
从以上输出信息可以看到，如果探测到目标主机上存在开放的端口，则推测出了其操作系统类型；如果目标主机上不存在开放的端口，则无法推测其操作系统类型。
（3）推测操作系统
当Nmap无法确定所探测的操作系统时，会尽可能地提供最相近的匹配。为了对目标系统推测得更准确，可以使用--osscan-guess或--fuzzy选项来实现。语法格式如下：
nmap-O--osscan-guess;--fuzzy[host]
其中，--osscan-guess;--fuzzy选项用于推测操作系统检测结果，将以百分比的方式给出对操作系统信息的猜测。当Nmap无法确定所检测的操作系统时，会尽可能地提供最相近的匹配。Nmap默认进行这种匹配，使用任意一个选项将使得Nmap的推测更加有效。
推测目标主机www.163.com的操作系统类型。执行命令如下：
root@daxueba:~#nmap-O--osscan-guesswww.163.com
StartingNmap7.70(https://nmap.org)at2021-08-0216:08CST
Nmapscanreportforwww.163.com(124.163.204.105)
Hostisup(0.015slatency).
Otheraddressesforwww.163.com(notscanned):2408:8726:5100::4f
rDNSrecordfor124.163.204.105:105.204.163.124.in-addr.arpa
Notshown:955closedports
PORTSTATESERVICE
80/tcpopenhttp
81/tcpopenhosts2-ns
82/tcpopenxfer
84/tcpopenctf
88/tcpopenkerberos-sec
135/tcpfilteredmsrpc
139/tcpfilterednetbios-ssn
443/tcpopenhttps
445/tcpfilteredmicrosoft-ds
……省略部分内容
Devicetype:generalpurpose|firewall|mediadevice|phone|broadbandroutersecurity-misc
Running(JUSTGUESSING):Linux3.X|2.6.X|4.X(92%),IPCop2.X(91%),Tiandy
embedded(91%),GoogleAndroid5.X(90%),D-Linkembedded(90%),Draytek
embedded(89%)
OSCPE:cpe:/o:linux:linux_kernel:3.2cpe:/o:linux:linux_kernel:2.6.32
cpe:/o:ipcop:ipcop:2.0cpe:/o:linux:linux_kernel:4.9cpe:/o:google:
android:5.0.1cpe:/h:dlink:dsl-2890alcpe:/o:linux:linux_kernel:2.6.25.20
cpe:/h:draytek:vigor_2960
AggressiveOSguesses:Linux3.2(92%),IPCop2.0(Linux2.6.32)(91%),Linux
2.6.32(91%),Linux4.9(91%),TiandyNVR(91%),Android5.0.1(90%),Linux
3.18(90%),D-LinkDSL-2890ALADSLrouter(90%),OpenWrtKamikaze8.09(Linux
2.6.25.20)(90%),Linux2.6.18-2.6.22(89%)
NoexactOSmatchesforhost(testconditionsnon-ideal).
NetworkDistance:9hops
OSdetectionperformed.Pleasereportanyincorrectresultsathttps://nmap.org/submit/.
Nmapdone:1IPaddress(1hostup)scannedin5.65seconds
以上输出信息显示了目标主机可能使用的操作系统列表。这里列举可能的系统类型，并以百分比形式显示每种类型的概率。从输出结果显示的比例中可以看到，目标主机的操作系统类型可能是Linux3.2。
2.Ping系统识别
Ping是Windows、UNIX和Linux系统下的一个命令，使用该命令可以检查网络是否连通。如果目标主机正确响应的话，在响应包中将包括有对应的TTL值。TTL是TimeToLive（生成时间）的缩写，该字段指定IP包被路由器丢弃之前允许通过的最大网段数量。其中，不同操作系统类型响应的TTL值不同。所以我们可以使用Ping命令进行系统识别。下面介绍使用Ping命令实施系统识别的方法。
为了能够快速地确定一个目标系统的类型，下面给出了一个操作系统初始TTL值列表，如表1所示。
表1各个操作系统的初始TTL值
使用Ping测试目标主机（192.168.33.152）的操作系统类型（该目标主机的操作系统类型为Linux）。执行命令如下：
root@daxueba:~#ping192.168.33.152
PING192.168.33.152(192.168.33.152)56(84)bytesofdata.
64bytesfrom192.168.33.152:icmp_seq=1ttl=64time=0.242ms
64bytesfrom192.168.33.152:icmp_seq=2ttl=64time=0.431ms
64bytesfrom192.168.33.152:icmp_seq=3ttl=64time=0.431ms
64bytesfrom192.168.33.152:icmp_seq=4ttl=64time=0.440ms
从输出的信息可以看到，响应包中的TTL值为64。根据前面列出的表格6.1，可以看到这是Linux操作系统。
使用Ping测试目标主机（192.168.33.229）的操作系统类型（该目标主机的操作系统类型为Windows7）。执行命令如下：
root@daxueba:~#ping192.168.33.229
PING192.168.33.229(192.168.33.229)56(84)bytesofdata.
64bytesfrom192.168.33.229:icmp_seq=1ttl=128time=1.57ms
64bytesfrom192.168.33.229:icmp_seq=2ttl=128time=1.01ms
64bytesfrom192.168.33.229:icmp_seq=3ttl=128time=0.276ms
64bytesfrom192.168.33.229:icmp_seq=4ttl=128time=1.52ms
从输出的信息可以看到，该响应包中的TTL值为128。由此可以说明，这是一个Windows操作系统。
3.xProbe2系统识别
xProbe2是一款远程主机操作系统探查工具，该工具通过ICMP协议来获得指纹。xProbe2通过模糊矩阵统计分析主动探测数据报文对应的ICMP数据报特征，进而探测得到远端操作系统的类型。下面介绍使用xProbe2工具实施操作系统指纹识别的方法。使用xProbe2工具实施系统识别的语法格式如下：
xProbe2[host]
使用xProbe2工具对目标主机www.163.com实施系统识别。执行命令如下：
root@Kali:~#xprobe2www.163.com
Xprobe2v.0.3Copyright(c)2002-2005fyodor@o0o.nu,ofir@sys-security.com,meder@o0o.nu
[+]Targetiswww.163.com#目标地址
[+]Loadingmodules.#正在加载模块
[+]Followingmodulesareloaded:#被加载的模块
[x][1]ping:icmp_ping-ICMPechodiscoverymodule
[x][2]ping:tcp_ping-TCP-basedpingdiscoverymodule
[x][3]ping:udp_ping-UDP-basedpingdiscoverymodule
[x][4]infogather:ttl_calc-TCPandUDPbasedTTLdistancecalculation
[x][5]infogather:portscan-TCPandUDPPortScanner
[x][6]fingerprint:icmp_echo-ICMPEchorequestfingerprintingmodule
[x][7]fingerprint:icmp_tstamp-ICMPTimestamprequestfingerprintingmodule
[x][8]fingerprint:icmp_amask-ICMPAddressmaskrequestfingerprintingmodule
[x][9]fingerprint:icmp_port_unreach-ICMPportunreachablefingerprintingmodule
[x][10]fingerprint:tcp_hshake-TCPHandshakefingerprintingmodule
[x][11]fingerprint:tcp_rst-TCPRSTfingerprintingmodule
[x][12]fingerprint:smb-SMBfingerprintingmodule
[x][13]fingerprint:snmp-SNMPv2cfingerprintingmodule
[+]13modulesregistered
[+]Initializingscanengine#初始化扫描引擎
[+]Runningscanengine#正在实施扫描
[-]ping:tcp_pingmodule:noclosed/openTCPportsknownon124.163.204.105.
Moduletestfailed
[-]ping:udp_pingmodule:noclosed/openUDPportsknownon124.163.204.105.
Moduletestfailed
[-]Nodistancecalculation.124.163.204.105appearstobedeadornoportsknown
[+]Host:124.163.204.105isup(Guessprobability:50%)#主机是活动的
[+]Target:124.163.204.105isalive.Round-TripTime:0.01503sec
[+]SelectedsafeRound-TripTimevalueis:0.03007sec
[-]fingerprint:tcp_hshakeModuleexecutionaborted(noopenTCPportsknown)
[-]fingerprint:smbneedeitherTCPport139or445torun
[-]fingerprint:snmp:needUDPport161open
[+]Primaryguess:#主要猜测
[+]Host124.163.204.105RunningOS:"LinuxKernel2.4.19"(Guess
probability:100%)
[+]Otherguesses:#其他猜测
[+]Host124.163.204.105RunningOS:"LinuxKernel2.4.20"(Guess
probability:100%)
[+]Host124.163.204.105RunningOS:"LinuxKernel2.4.21"(Guess
probability:100%)
[+]Host124.163.204.105RunningOS:"LinuxKernel2.4.22"(Guess
probability:100%)
[+]Host124.163.204.105RunningOS:"LinuxKernel2.4.23"(Guess
probability:100%)
[+]Host124.163.204.105RunningOS:"LinuxKernel2.4.24"(Guess
probability:100%)
[+]Host124.163.204.105RunningOS:"LinuxKernel2.4.25"(Guess
probability:100%)
[+]Host124.163.204.105RunningOS:"LinuxKernel2.4.26"(Guess
probability:100%)
[+]Host124.163.204.105RunningOS:"LinuxKernel2.4.27"(Guess
probability:100%)
[+]Host124.163.204.105RunningOS:"LinuxKernel2.4.28"(Guess
probability:100%)
[+]Cleaningupscanengine
[+]Modulesdeinitialized
[+]Executioncompleted.
从输出的信息中可以看到，通过xProbe2工具成功解析出了目标主机的IP地址，并且识别出了其操作系统类型。其中，目标主机的IP地址为124.163.204.105，操作系统类型为Linux，内核版本在2.4.19～2.4.28之间。
xProbe2工具在NAT模式下存在Bug，扫描后会出现HP的位置或者直接报错，具体如下：
root@Kali:~#xprobe2www.163.com
Xprobe2v.0.3Copyright(c)2002-2005fyodor@o0o.nu,ofir@sys-security.com,meder@o0o.nu
[+]Targetiswww.163.com
[+]Loadingmodules.
[+]Followingmodulesareloaded:
[x][1]ping:icmp_ping-ICMPechodiscoverymodule
[x][2]ping:tcp_ping-TCP-basedpingdiscoverymodule
[x][3]ping:udp_ping-UDP-basedpingdiscoverymodule
[x][4]infogather:ttl_calc-TCPandUDPbasedTTLdistancecalculation
[x][5]infogather:portscan-TCPandUDPPortScanner
[x][6]fingerprint:icmp_echo-ICMPEchorequestfingerprintingmodule
[x][7]fingerprint:icmp_tstamp-ICMPTimestamprequestfingerprintingmodule
[x][8]fingerprint:icmp_amask-ICMPAddressmaskrequestfingerprintingmodule
[x][9]fingerprint:icmp_port_unreach-ICMPportunreachable
fingerprintingmodule
[x][10]fingerprint:tcp_hshake-TCPHandshakefingerprintingmodule
[x][11]fingerprint:tcp_rst-TCPRSTfingerprintingmodule
[x][12]fingerprint:smb-SMBfingerprintingmodule
[x][13]fingerprint:snmp-SNMPv2cfingerprintingmodule
[+]13modulesregistered
[+]Initializingscanengine
[+]Runningscanengine
[-]ping:tcp_pingmodule:noclosed/openTCPportsknownon124.163.204.105.
Moduletestfailed
[-]ping:udp_pingmodule:noclosed/openUDPportsknownon124.163.204.105.
Moduletestfailed
[-]Nodistancecalculation.124.163.204.105appearstobedeadornoportsknown
[+]Host:124.163.204.105isup(Guessprobability:50%)
[+]Target:124.163.204.105isalive.Round-TripTime:0.01528sec
[+]SelectedsafeRound-TripTimevalueis:0.03056sec
[-]fingerprint:tcp_hshakeModuleexecutionaborted(noopenTCPportsknown)
[-]fingerprint:smbneedeitherTCPport139or445torun
[-]fingerprint:snmp:needUDPport161open
[+]Primaryguess:
[+]Host124.163.204.105RunningOS:"HPJetDirectROMG.07.02EEPROMG.07.17"(Guessprobability:83%)
[+]Otherguesses:
[+]Host124.163.204.105RunningOS:"HPJetDirectROMG.07.02EEPROMG.07.20"(Guessprobability:83%)
[+]Host124.163.204.105RunningOS:"HPJetDirectROMG.07.02EEPROMG.08.04"(Guessprobability:83%)
[+]Host124.163.204.105RunningOS:"HPJetDirectROMG.07.19EEPROMG.07.20"(Guessprobability:83%)
[+]Host124.163.204.105RunningOS:"HPJetDirectROMG.07.19EEPROMG.08.03"(Guessprobability:83%)
[+]Host124.163.204.105RunningOS:"HPJetDirectROMG.07.19EEPROMG.08.04"(Guessprobability:83%)
[+]Host124.163.204.105RunningOS:"HPJetDirectROMG.08.08EEPROMG.08.04"(Guessprobability:83%)
[+]Host124.163.204.105RunningOS:"HPJetDirectROMG.08.21EEPROMG.08.21"(Guessprobability:83%)
[+]Host124.163.204.105RunningOS:"HPJetDirectROMH.07.15EEPROMH.08.20"(Guessprobability:83%)
[+]Host124.163.204.105RunningOS:"HPJetDirectROMG.06.00EEPROMG.06.00"(Guessprobability:83%)
[+]Cleaningupscanengine
[+]Modulesdeinitialized
[+]Executioncompleted.
从以上输出的信息中可以看到，执行结果出错了（HPJetDirectROMG.07.02EEPROMG.07.17）。
在KaliLinux的新版本中，xProbe2工具运行后，测试的结果中操作系统类型显示为乱码。具体如下：
[+]Primaryguess:
[+]Host192.168.1.8RunningOS:????U(Guessprobability:100%)
[+]Otherguesses:
[+]Host192.168.1.8RunningOS:?????U(Guessprobability:100%)
[+]Host192.168.1.8RunningOS:?????U(Guessprobability:100%)
[+]Host192.168.1.8RunningOS:?????U(Guessprobability:100%)
[+]Host192.168.1.8RunningOS:????U(Guessprobability:100%)
[+]Host192.168.1.8RunningOS:?????U(Guessprobability:100%)
[+]Host192.168.1.8RunningOS:????U(Guessprobability:100%)
[+]Host192.168.1.8RunningOS:?????U(Guessprobability:100%)
[+]Host192.168.1.8RunningOS:?????U(Guessprobability:100%)
[+]Host192.168.1.8RunningOS:?????U(Guessprobability:100%)
[+]Cleaningupscanengine
[+]Modulesdeinitialized
[+]Executioncompleted.
4.p0f系统识别
p0f是一款用于识别远程操作系统的工具，该工具与前面介绍的其他工具不同，它是一个完全被动地识别操作系统指纹信息的工具，不会直接作用于目标系统。当启动该工具后，即可监听网络中的所有数据包。通过分析监听到的数据包，即可找出与系统相关的信息。下面介绍使用p0f工具来实施操作系统指纹识别的方法。
使用p0f工具对目标主机实施系统识别。执行命令如下：
1）启动p0f工具。执行命令如下：
root@daxueba:~#p0f
---p0f3.09bbyMichalZalewski<lcamtuf@coredump.cx>---
[+]Closed1filedescriptor.
[+]Loaded322signaturesfrom'/etc/p0f/p0f.fp'.
[+]Interceptingtrafficondefaultinterface'eth0'.
[+]Defaultpacketfilteringconfigured[+VLAN].
[+]Enteredmaineventloop.
从以上输出信息中可以看到，p0f工具仅显示了几行信息，无法捕获到其他信息。但是，p0f会一直处于监听状态。
2）此时，当有其他主机在网络中产生数据流量的话，将会被p0f工具监听到。例如，在另一台主机上通过浏览器访问一个站点，然后返回到p0f所在的终端，将看到如下信息：
.-[192.168.1.4/38934->65.200.22.161/80(httprequest)]-#HTTP请求
|client=192.168.1.4/38934#客户端
|app=Safari5.1-6#应用
|lang=English#语言
|params=dishonest#程序
|raw_sig=1:Host,User-Agent,Accept=[*/*],Accept-Language=[en-US,en;q=0.5],Accept-Encoding=[gzip,deflate],?Cache-Control,Pragma=[no-cache],Connection=[keep-alive]:Accept-Charset,Keep-Alive:Mozilla/5.0(X11;Linuxx86_64;rv:60.0)Gecko/20100101Firefox/60.0#数据内容
----
.-[192.168.1.4/38934->65.200.22.161/80(uptime)]-
|server=65.200.22.161/80#服务器
|uptime=30days0hrs22min(modulo45days)#时间
|raw_freq=1048.46Hz#频率
----
.-[192.168.1.4/38934->65.200.22.161/80(httpresponse)]-
|server=65.200.22.161/80
|app=???
|lang=none
|params=none
|raw_sig=1:Content-Type,?Content-Length,?Last-Modified,?ETag,Accept-Ranges=[bytes],Server,X-Amz-Cf-Id=[X7nIiIIBBeQOTeLSHRH3U4SM6xDHfgwK1EaKf8bdyemtuUoR8JK9Xg==],?Cache-Control,Date,Connection=[keep-alive]:Keep-Alive:AmazonS3
----
.-[192.168.1.4/32854->52.27.184.151/443(syn)]-
|client=192.168.1.4/32854
|os=Linux3.11andnewer
|dist=0
|params=none
|raw_sig=4:64+0:0:1460:mss*20,7:mss,sok,ts,nop,ws:df,id+:0
----
.-[192.168.1.4/32854->52.27.184.151/443(hostchange)]-
|client=192.168.1.4/32854
|reason=tstampport
|raw_hits=0,1,1,1
----
.-[192.168.1.4/32854->52.27.184.151/443(mtu)]-
|client=192.168.1.4/32854
|link=Ethernetormodem
|raw_mtu=1500
----
.-[192.168.1.4/32856->52.27.184.151/443(syn)]-
|client=192.168.1.4/32856
|os=Linux3.11andnewer
|dist=0
|params=none
|raw_sig=4:64+0:0:1460:mss*20,7:mss,sok,ts,nop,ws:df,id+:0
----
以上输出的信息，就是执行监听到客户端访问的数据信息。从以上输出的信息可以看到，探测到客户端的操作系统类型为Linux3.11或更新的内核版本。