????????????????????????????????????????????????????????????
??????????????
?????????缼???У?????Port????????????????????????????????????????????????????ADSLModem??????????????????·???????????????????????豸???????RJ-45????SC?????????????????????????????????????????TCP/IPЭ???е?????????????Χ??0??65535?????????????????????80????????FTP?????21??????????????????????????????????????????????????????????????????
?????????????????3????
????1?????????WellKnownPort??
????????????0??1023?????????????Щ????????????FTP?????????21??????/etc/services?????????????????????
????2????????RegisteredPorts):
??????1024??49151???????????????Щ?????????????????????Щ??????Щ????????????????????.
????3:???????ж???Dynamicand/orPrivatePorts??
????????????????????privateportnumbers?????????????????????κ?????????????????????????????????????Э?飬?????????Э?顣??????????49152??65535
????Linux?????????????÷?Χ???????????????????Щ???????????????????????Χ??/proc/sys/net/ipv4/ip_local_port_range?????????TCP/UDP?????Χ?????????/etc/sysctl.conf???漲??net.ipv4.ip_local_port_range=102465000
????[root@localhost~]#cat/proc/sys/net/ipv4/ip_local_port_range
????3276861000
????[root@localhost~]#echo102465535>/proc/sys/net/ipv4/ip_local_port_range
?????????????????????ù????????????????????????????????????????????????????????????ν?????????????Щ????????????????????????????????????????????Щ????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????д????????????Щ?????????Щ????????????????????????????????????????????????????????????????????????????????????????????????????????????????磬??????????????????????????????????????????????????ó???????????????IP????
???????????????
??????????????????????????????IP?????????????????????????Web????FTP????SMTP????????Щ??????????????1??IP????????????????????????????????????????????????????IP????????IP????????????????????????????????????“IP???+????”???????????????
????????????????????????????/etc/services????У????????п?????????????
??????μ??????????????????????????????????????
????1??nmap??????????
????nmap?????????????????????????nmap??????????????????rpm????????
[root@DB-ServerServer]#rpm-ivhnmap-4.11-1.1.x86_64.rpm
warning:nmap-4.11-1.1.x86_64.rpm:HeaderV3DSAsignature:NOKEY??keyID37017186
Preparing...###########################################[]
1:nmap###########################################[]
[root@DB-ServerServer]#rpm-ivhnmap-frontend-4.11-1.1.x86_64.rpm
warning:nmap-frontend-4.11-1.1.x86_64.rpm:HeaderV3DSAsignature:NOKEY??keyID37017186
Preparing...###########################################[]
1:nmap-frontend###########################################[]
[root@DB-ServerServer]#
????????nmap????????????????д??д??????????????????????nmap127.0.0.1??????????????????????ж????????????????????????????
[root@DB-ServerServer]#nmap127.0.0.1
StartingNmap4.11(http://www.insecure.org/nmap/)at2016-06-2215:46CST
Interestingportsonlocalhost.localdomain(127.0.0.1):
Notshown:1674closedports
PORTSTATESERVICE
22/tcpopenssh
25/tcpopensmtp
111/tcpopenrpcbind
631/tcpopenipp
1011/tcpopenunknown
3306/tcpopenmysql
Nmapfinished:1IPaddress(1hostup)scannedin0.089seconds
Youhavenewmailin/var/spool/mail/root
[root@DB-ServerServer]#

????2??netstat??????????
[root@DB-ServerServer]#netstat-anlp|grep3306
tcp00:::3306:::*LISTEN7358/mysqld
[root@DB-ServerServer]#netstat-anlp|grep22
tcp00:::22:::*LISTEN4020/sshd
tcp052::ffff:192.168.42.128:22::ffff:192.168.42.1:43561ESTABLISHED6198/2
[root@DB-ServerServer]#

????????????????????о????nmap?????????????????nmap???????