????3??lsof??????????
[root@DB-ServerServer]#servicemysqlstart
StartingMySQL......[OK]
[root@DB-ServerServer]#lsof-i:3306
COMMANDPIDUSERFDTYPEDEVICESIZENODENAME
mysqld7860mysql15uIPv644714TCP*:mysql(LISTEN)
[root@DB-ServerServer]#servicemysqlstop
ShuttingdownMySQL..[OK]
[root@DB-ServerServer]#lsof-i:3306
[root@DB-ServerServer]#

[root@DB-ServerServer]#lsof-iTCP|fgrepLISTEN
cupsd3153root4uIPv49115TCPlocalhost.localdomain:ipp(LISTEN)
portmap3761rpc4uIPv410284TCP*:sunrpc(LISTEN)
rpc.statd3797rpcuser7uIPv410489TCP*:1011(LISTEN)
sshd4020root3uIPv612791TCP*:ssh(LISTEN)
sendmail4042root4uIPv412876TCPlocalhost.localdomain:smtp(LISTEN)
????4?????telnet??????????
??????????????????????????????????iptables???????????????????÷???????????????
????5??netcat??????????????
[root@DB-Server~]#nc-vv192.168.42.1281521
Connectionto192.168.42.1281521port[tcp/ncube-lm]succeeded!
[root@DB-Server~]#nc-z192.168.42.1281521;echo$?
Connectionto192.168.42.1281521port[tcp/ncube-lm]succeeded!
0
[root@DB-Server~]#nc-vv192.168.42.1281433
nc:connectto192.168.42.128port1433(tcp)failed:Noroutetohost
???????????????
???????????????????????????????????????ж?????????????????????????????????????????????????????MySQL???????3306??????????????MySQL????????3306??????????
[root@DB-ServerServer]#servicemysqlstart
StartingMySQL......[OK]
[root@DB-ServerServer]#lsof-i:3306
COMMANDPIDUSERFDTYPEDEVICESIZENODENAME
mysqld7860mysql15uIPv644714TCP*:mysql(LISTEN)
[root@DB-ServerServer]#servicemysqlstop
ShuttingdownMySQL..[OK]
[root@DB-ServerServer]#lsof-i:3306
[root@DB-ServerServer]#
?????????????????Щ????????????????????????????????????ù????Щ?????????????????????????????????????????????????????????????????????????????????????????й????????????????