pGz``Whdݤ@ǸƪܡAרO Unix-Like @~tΡAp FreeBSD, Unix, Linux Aӷ|``ť daemons oӦrA daemon OFrIHo`QHADaemon rWNNOyu@Bc]HzٯuOI_I ^_^"" C򥻤WAڭ̪ Linux D``|@ǭnDA׬OӦۥtΪnDΪ̬O Client ݪAȭnDAϥunnDӪɭԡAq`NOUU˪ daemons tdh_ӭnu@ Servers Ӥu@աI daemons ثeذ򥻪ҦAOO stand_alone P super daemon ؤ觋AUNӻ@o daemon u@AG

•  stand_alone G NrWNӻAstand alone NOyWߪҰʡzNA]NOA daemon ҰʤAN`nbOoILM|@ΨtΪ귽A̤juINOAL|@ҰʪաIҥHnDӪɭԡALN|ܧֳt^oI``Φbo@ daemon AȦp` httpd o@ӧYO@ҡI

• super daemon G ۹ stand alone 觋Ao@تAȪҰʤ觋hOǥѲΤ@@ daemon ӭtd_ӪAȡIo@ӲΤ@td daemon NO inet oAȰաILAbӪ Linux oiM󤤡AhOϥ xinet oӳ]woIڭ̳o̥H Mandrake xinet ӰCAȭnDӪɭԡAӭnD|e xinet oӪAȡAM xinet ھڸӺnDeӪƫʥ]e ( Ӥe|O IP P port ) ӱNƫʥ]eڹB@AȡIӸӪAȳoӮɭԤ~|ҰʪI̱`쪺NO ftp oAȰաIoس̤juINOSƫʥ]ӪɭԡAӪAȤ|@ڨtθ귽 ( ӪAȷ|b sleeping AaI ) AO۹諸ALɶ]|CA]٭nO@qɶhyzӪAȧrI

oرҰʪ觋@ӤnOHաIӥB٭nݸӥDu@tPڪγ~IҦpADOΨӧ@ WWW AA httpd ۵MNH stand alone Ұʤ觋ΡIƹWAڭ̱``} stand alone P super daemon pAiHȦ檺fӧ@dҡI

• stand alone G bȦ̭A]@س@AȪfAҦpsfAҥHAAݭnsɭԡAeӵfANyMHzzAȰաI

• super daemon G bȦ̭]٦t~@ؽƦXAfAPɴbBիסBڵ~ȡAAݭn𫟺@~ȪɭԡANݭneӵfAObfo~AAݨD椧A᭱@yޡIbSIӧAu@Fz򨺭ӤSN}lu@hIMӸY٦ի׻Pڵtd~ȪSOHL̦bFHKKIݬݳBܳܯoIo̴N|ޥXt~@ӰDաI]Ȧ椵ѪHSOAҥHoӵf᭱FA~٦ܦhHIQ@QAoӵfOny@ӧAӤU@ӡz٬OyA̪ڮӡAڥBzzOHIOOӤ@ˡH

@
• multi-threadedGNOڭ̴쪺AȤᤧnDLӡA@LUhAҥH@ӪAȦPɷ|tdnXӵ{ǡC
@
• single-threadedGoӴNOثeڭ̡yHȦẕ`觋աAצpAϥ@Ӥ@ӨӡAĤ@ӨSBzeA᭱бƶIKKIҥHpG client nDMjWܡAoDZߨ쪺 client ioW@I

t~Aݭn`NOAJMȦYoصfPɦsbAҥHoAb Linux tθ̭Ao daemon OiHPɦsbաI]NOAYǪAȥiHϥ stand alone ӱҰʡAӦLAȫhiHϥ xinet ( Ϊ̬O inet ) jPpNOo˰աIFIIH

---

• /etc/services

OOKIoӮɭԴNSoͤFt@ӰDoIګ򪾹DnNڪưe쨺ӵfhIxIӵfOgLOFΪܡHҥHAnsBbBΪ̬Oi״ڡAiHbPfӧA򴫨ڪpӻOA]ڭ̪ TCP ʥ]̭t port P IP aINǤwgť port QOoǵfAp@ӧA TCP ʥ]KiH̾ڤPݨDAӨF@˪ port ӯAȤFI]AAsuO FTP, WWW, smtp nA藍|QdաI
@
nFApGڷQnDo port OѨӪAȩұҰʪOHb Linux tθ̭ɮצbӵfPAȪ  ( services and ports ) IINOjW /etc/services oɮװաIڭ̨@q``ݨ쪺 port PAȪϬqӬݤ@UnFI
@

[root @test root]# vi /etc/services .... ftp-data        20/tcp ftp-data        20/udp ftp             21/tcp ftp             21/udp ssh             22/tcp                          # SSH Remote Login Protocol ssh             22/udp                          # SSH Remote Login Protocol telnet          23/tcp telnet          23/udp smtp            25/tcp          mail smtp            25/udp          mail nameserver      42/tcp          name            # IEN 116 nameserver      42/udp          name            # IEN 116 domain          53/tcp          nameserver      # name-domain server domain          53/udp          nameserver .... <daemon name>   <port PA>   < ӪAȪ >

@
WOAĤ@欰 daemon W١BĤG欰 daemon ҨϥΪ port XPƫʥ]ǰeɭԪADníw tcp ʥ]P}lֳt udp ʥ]I|ӨҤlA e-mail oHw smtp oӪAȡAӳoӪAȪϥΤ port Y 25 աINoˡI
@
• ЯSO`NIMɭԱziHǥѭק /etc/services ӧ@ӪAȪ port ALäijpA]ܦi|y@Ǩw~pIo̯S@fI]Dzn[]@ӦaUA_hܡAϥ /etc/services ]wNnաI^

---

• Daemon RWWhG

C@ӪAȪ}o̡Ab}oL̪AȮɡASOGưաILALצpAoǪAȪWٳQإߤAQW Linux ϥήɡAq`bAȪW٤|[W@ d AҦpҦʩROإߪ at, P cron oӪAȡAq`|Q٬ atd P crondAo d NNO daemon NCҥHAb귽޲z@Aڭ̨ϥΤF ps P top [{ǮɡA|o{ܦh xxxd {ǡAIq`NO@ daemon {oI

nFIڭ̤wgDF daemon @ΤAAӭnQתOAḺҰʪ scripts Ob̧rIHIUNӻ@oG

• stand alone G oөmb /etc/rc.d/init.d/ oӥؿ̭AXGҦ RPM w˪M󤧱Ұʶسbo̰աI

• super daemon G oӤu@@AȨNO xinet Ϊ̬O inet աIЪ`NA xinet ]O@ daemon OILO stand alone ҰʪA]NOL|@bťjaݨDAҥH xinet Ұ scripts gb /etc/rc.d/init.d/xinetd o scripts ̭oIObo daemon YAȤ]wةOHINOgb /etc/xinetd.conf P /etc/xinetd.d/ oӥؿ̭ɮסI

---

• /etc/rc.d/init.d/*

OKIAѤ@U stand alone daemon OҰʪOHI²Apڭ̭nҰ syslog oOnɪAȡAnҰʥLܡANUFG
• /etc/rc.d/init.d/syslog start
• service syslog start
YOɦW[W start YiAΪ̬Oϥ Red Hat ~o service script ӶiҰʪ\IpGAٰOoڭ̫eX`L shell scripts ܡAγ\ٰOo case ..... esac oӦܩʪتykaIHSIoXAȴNOH bash scripts Y case ykgI]Aun[W᭱ѼơAp@ӡA scripts N|۰ʪhMɨӰoIpG쪺ܡAiHbAtθ̭ӥؿU}@ɮר[ݤ@UANDpgoI

---

• /etc/xinetd.conf

oɮ״NO]w xinet AȪѼɮװաI

---

• /etc/xinetd.d/*

oӥؿ̭Ҧɮ״NOӧOW xinet ҦAȰաIҦpW wu-ftpd telnet P pop3 I

@ӨAb /etc/rc.d/init.d/ ̭ scripts Ooi̤ RPM ҴѪApGzۦoiAn骺ܡAiHHo˪觋ӿW߱ҰʪILAڭ̤]iHg super daemon Ӻ޲zڭ̪AȡA]o super daemon iHѬ۷h\AרOwʤ譱\AҥHAڭ̴Nӽͤ@ͦpϥγoӪFaI
@
Ӭݤ@ݹw] /etc/xinetd.conf oɮתeOaI
@

# # Simple configuration file for xinetd # # Some defaults, and include /etc/xinetd.d/ defaults {         instances               = 60         log_type                = SYSLOG authpriv         log_on_success          = HOST PID         log_on_failure          = HOST         cps                     = 25 30 } includedir /etc/xinetd.d

e榡G service <service_name> {        <attribute> <assign_op> <value> <value> ...        ... }

@
bWw]dҷAOGypGSw services ( defaults ) N {} ̭]wӰ椧Iz`pUIWҤlrҥܡA <> YƧڭ̥ӻ@UGG assign_op DnTاΦAOpUG

 = G ܫ᭱]wѼƴNOo˰աI
+= G ܫ᭱]wybӪ]wY[JsѼz
-+ G ܫ᭱]wybӪѼƱ˱o̿JѼIz

γ~ӬۦPAqЯdNInFIUAӻ@ attribute P value I
 

attribute (\)	assing_op (\ʧ@)	(d)
@]wءG
disable	yes no	\ server iHΪ̬OI ]w yes ܸӪAȤI
socket_type	stream dgram raw	su TCP ʥ]ɡAhϥ stream su UDP ʥ]ɡAhϥ dgram  raw N server ݭnP IP ͡I
protocol	tcp udp ...	oӪF軡OAsuAϥΪO@بwIHUӨwNiHѦ /etc/protocols eI~ADOAۤv]wAȡA_hoӥiHγ]wաI
wait	yes no	oNOڭ̭责쪺 Multi-threaded P single-threaded 觋աI@ӻAڭ̧ƱjanDiHPɳQҥΡAҥHiH]w wait = no
user	UID root	ٰOoڭ̦b b޲z @g쪺 UID ܡHաIo UID NO UID աIn`NOApAAȱҰʪ̤nH root DܡAoӦaNiHܨLϥΪ̡AҦp nobody IoөNN]|w@sbI~Aݭn`No UID sb /etc/passwd C
group	GID	user NۦPIuOo GID ϥΪ̤]sb /etc/group I
instances	number UNLIMITED	oӬOybP@ɶAP@ӪAȥiH\suƥzNAAiHgJ@ӡyƦrzӱsuƥءA]iHϥ UNLIMITED ӧiDtΡySWzoIҦpAbPɬqȤ\ ftp su 30 ӡAo̴NiHJ 30 աI
nice	-19 ~ 19	ٰOoڭ̦b {Ǻ޲z ̭ͨ쪺 nice OܡHIաIo̴NOoӪFoIƦrVp( t )Nӵ{ǶVuQI
server	program /usr/sbin/in.ftpd	oӴNOXoӪAȪҰʵ{IҦpnҰ ftp ܡANO in.ftpd o{աIҥHoӮɭԦbo̿J server = /usr/sbin/in.ftpd
server_args	@ǰѼ	oӿJNOA server ̻ݭnJ@ǰѼưաIҦp in.ftpd Aڭ̥iNݭnJ -l -a oӰѼƻI
log_on_success	PID HOST USERID EXIT DURATION	by\nJzAݭnOءGPID server ҰʮɭԪ process ID AHOST ݥD IPBUSERID nJ̪bBEXTI }ɭ԰OءBDURATION ӨϥΪ̨ϥΦAȦh[H
log_on_failure	HOST USERID ATTEMPT RECORD	nJѤQ syslog nJءGHOSTݥD IPAUSERIDnJ̱bBATTEMPTOnJѪ̥ϪNϬBRECORDOݥDTIHά󥻾 server Ұʪ]IDn login, shell, exec, finger OiHϥΦbo̡I( 򥻤WAiHb /etc/hosts.allow /etc/hosts.deny Ѽge )C
i]wءG
env	'name=value'	o@ӶإiHA]wܼơAܼƪ]wWhiHѦ { BASH Shell C
port	number	o̥iH]wPAȻP port AOаOA port PAȦW٥P /etc/services OۦP~I
redirect	IP_Address port	N client ݹڭ server nDAt@DWhIIoӦnIҦpHnϥΧA ftp ɡAAiHNLt@WhI IP_Address NNt@ݥD IP oI
includedir	directory_path	ܱNYӥؿUҦɮ׳Li xinetd.conf oӳ]wYIoF観ΦhFAp@ӧڭ̥iH@Ӥ@ӳ]wPءIӤݭnNҦAȳgb xinetd.conf IAiHb /etc/xinetd.conf o{oӳ]wI
w޶ءG
bind	IP_Address	oӬO]wy\ϥΦ@AȪdzNI|ӨҤlӻAA Linux DW IP AӧAuQn IP1 iHϥΦ@AȡA IP2 ϥΦAȡAo̴NiHN IP1 gJYiI IP2 NiHϥΦ@ server oI
interface	IP_Address	bind ۦPI
only_from	0.0.0.0 192.168.1.0/24 host_name domain_name	oFΦbwWA]NOިyuo̭Ww IP Ϊ̬ODW٥iHnJIzpGO 0.0.0.0 ܩҦ PC ҥinJApGO 192.168.1.0/24 hܬ C class IY 192.168.1.1 ~ 192.168.1.255 ҥinJIt~A]iH domain name AҦp .ev.ncku.edu.tw NiHjut IP nJADϥθ server I
no_access	0.0.0.0 192.168.1.0/24 host_name domain_name	only_from thաINOΨӺ޲zi_iJA Linux DҥΧA server AȪ޲zءI no_access ܡyinJz PC oI
access_times	00:00-12:00 HH:MM-HH:MM	oӶئb]wyӪA server ҰʪɶzAϥΪO 24 pɪ]wIҦpA ftp nb 8 I 16 I}񪺸ܡANOG 08:00-16:00C
umask	000 777 022	ٰOob ɮv ̭L umask oӪFܡHISINOӰNoIiH]wϥΪ̫إߥؿΪ̬Oɮ׮ɭԪݩʡItΫijȬO 022 C

MWѼƤݭnCӳ]wաIun]wݭnNiHաIӦb /etc/xinetd.conf oɮ׷A@w|ݨy includedir = /etc/xinetd.d zo@IoOAF /etc/xinetd.conf ~AҦb /etc/xinetd.d ɮ׳OiHΨӳ]wաIInFAڭ̨|²檺 telnet ҤlaINO /etc/xinetd.d/telnet oɮסApGA Mandrake 9.0 SoɮסA٨Swtelnet-server-krb5-1.2.5-1mdkoӮMAХw˥LaIMALeIoˡG
@

service telnet { @@@@disable@@@@ = yes@@@@@@@@ <==Aȹw]O @@@@flags@@@@@ = REUSE@@@@@@@ <==B~ϥΪѼ @@@@socket_type@@ = stream@@@@@@@<==ϥ tcp ʥ]`ΪsuA @@@@wait@@@@@@= no @@@@@@@@ <==ݵݡAiHPɤ\hӳsu @@@@user@@@@@@= root@@@@@@@@<==Ұʵ{ǪϥΪ̨ @@@@server@@@@@= /usr/sbin/telnetd@ <==AȱҰʪ{ @@@@server_args@@ = -a none @@@@@@<==Wӵ{Ѽ @@@@log_on_failure@+= USERID @@@@@@<==~nJɡAnOUӪe }

@
W椤AwgFC@ѼƪNqIpG쥻w]ȧAäNAAiHק令wPh@IC]Ao Linux O@DAӥBLAOO~ 140.116.44.125 P鷺 192.168.0.254 oӡApGAQn鷺PAӹ~YAAiHo˪ӳ]wOG
@

# w鷺Pӳ]wG service telnet { @@@@disable@@@@ = no@@@@@@@@  <==w]NOҰ telnet A @@@@bind @@@@@ = 192.168.0.254@@@ <==u\gѳoӤdʥ]i @@@@only_from @@@= 192.168.0.0/24@@@<==u\ 192.168.0.0/24 oӺq @@@@@@@@@@@@@@@@@@@@@@@@ DsuiӨϥ telnet A @@@@instances @@@= UNLIMITED @@@@@<==Pɤ\suI @@@@nice @@@@@ = 0 @@@@@@@@@<==ϥΪuǸ @@@@flags@@@@@ = REUSE @@@@@@@<==B~ϥΪѼ @@@@socket_type @@= stream@@@@@@@<==ϥ tcp ʥ]`ΪsuA @@@@wait@@@@@@= no@@@@@@@@@<==ݵݡAiHPɤ\hӳsu @@@@user@@@@@@= root@@@@@@@@<==Ұʵ{ǪϥΪ̨ @@@@server @@@@ = /usr/sbin/telnetd @<==AȱҰʪ{ @@@@server_args@@ = -a none @@@@@@<==Wӵ{Ѽ @@@@log_on_failure@+= USERID @@@@@@<==~nJɡAnOUӪe } # Aw~suӶi歭OI service telnet { @@@@disable@@@@ = no                  <==w]NOҰ telnet A @@@@bind @@@@@ = 140.116.44.125      <==u\gѳoӤdʥ]i @@@@only_from @@@= 140.116.0.0/16      <==u\ 140.116.0.0 ~ 140.116.255.255                                                 oӺqsuiӨϥ telnet A @@@@only_from @@@= .edu.tw             <==Ƴ]wAuаȬɤ~suI @@@@no_access @@@= 140.116.32.{10,26}  <==\o PC nJ @@@@access_times@@= 1:00-9:00 20:00-23:59                                               <==CѥuoӮɬq}A @@@@umask @@@@@= 022                 <==إɮ׮ɪw]ݩʳ]w @@@@instances @@@= 10                  <==Pɥu\ 10 ӳsu @@@@nice@@@@@@= 10                  <==ϥΪuǸC @@@@flags @@@@@= REUSE               <==B~ϥΪѼ @@@@socket_type @@= stream              <==ϥ tcp ʥ]`ΪsuA @@@@wait@@@@@@= no                  <==ݵݡAiHPɤ\hӳsu @@@@user@@@@@@= root                <==Ұʵ{ǪϥΪ̨ @@@@server@@@@@= /usr/sbin/telnetd   <==AȱҰʪ{ @@@@server_args @@= -a none             <==Wӵ{Ѽ @@@@log_on_failure@+= USERID             <==~nJɡAnOUӪe }

IpW]wAڭ̥iHN telnet ҰʶضihIp@ӡANUڭ̪w@OIרpGiHw藍Pӳ]wAKKIN[oILAЪ`NIpGӤW]wAzDWN|}F 23 port AOOӤӨϥΪOIIun?P˪AA]iHwۤvߦnӳ]wAL daemon ϥLb xinetd UOI

nFAۤUӧڭ̭nӻ@AF xinetd ~A٦t@ӥiHקQάYǪAȶiJ Linux DkANO``ϥΪ /etc/hosts.allow P /etc/hosts.deny oIoӤ觋Oڭ̱``bϥΪkAo̥XӤ²檺]w觋IG TCP_Wrappers ]iH@ӳ̤hFA]O̤hAҥHMn]wYoI
@
s TCP_Wrappers OH wrappers ]qNAҥHAoӮM󥻨\NObR TCP ƫʥ]աIڭ̵yLڭ̺ʥ]ƥDnOH TCP ʥ]DAo TCP ʥ]YܤְOFӷPإD IP P port A]AYǥѤR TCP ʥ]ANiHݧڭnnoӸƶiJḒoIҥHաAڭ̭nϥ TCP_Wrappers ӱުANO

1. ӷ IP
2. port (NOAȰ)

TCP_Wrappers ]w TCP ʥ]O_iHiJ]wɦb /etc/hosts.allow P /etc/hosts.deny C]A򥻤WApG@ӪAȬO xinetd TCP_Wrappers ɡAӪAȴN| hosts.allow P hosts.deny ޲zFIӦpGAۤvw˪M( Yϥ Tarball w˪觋M )ADۦwq䴩 TCP_Wrappers \ A_hNLkϥγoӪNoIKKI
@
oɮ׬OFΪH褣OLILDnOΨӳWd TCP ʥ]WhAҥHOA̭OMNOGyY IP bSwAȤO_iJDzIngHoɮתe򥻪ykOG
@

<service> : <IP, domain, hostname...> : <allow|deny>

@
ҥHڭ̭nXӨ service_name ~AҦpHڭ̭𫍧 telnet ҡA service_name OOHNOW server oӳ]w᭱{WٰաIҥHA telnet b Mandrake UW٬ telnetd ( `NAbL distribution AoӦW٥i|ܡAҦp Red Hat OpenLinux OH in.telnetd WIҥHo̽аѦұztθ̭]wөwI)C ]ApGAQ 140.116.44.202 oӦ} 140.116.32.0/255.255.255.0 o C class iJADܡAiHo˦b /etc/hosts.deny ̭]wG
@

[root @test root]# vi /etc/hosts.deny telnetd:  140.116.44.202 : deny telnetd:  140.116.32.0/255.255.255.0 : deny

@
oˤ@ӡANLkH telnet iJADաIKaILAJMpAn]w /etc/hosts.allow /etc/hosts.deny ɮשOHI򥻤WAL̨ӪYG

1. ɮ /etc/hosts.allow sbɡAhHɮפ]wǡF
2. Ӧb /etc/hosts.allow SWw쪺ƶANb /etc/hosts.deny ~]wI

]NOA /etc/hosts.allow ]wu /etc/hosts.deny oIAѤFܡH򥻤WAun hosts.allow ]NFA]ڭ̥iHN allow P deny gbP@ɮפAuOoˤ@ӦGoIõLA]Aq`ڭ̳OG

1. \iJgb /etc/hosts.allow F
2. \iJhgb /etc/hosts.deny C

 Ajդ@A service_name yݡzA xinetd Ϊ̬O /etc/rc.d/init.d/* ̭{W٭nۦPCnFAڭ٬OH telnet ҤlӻnFA{b]@Ӥwy{ӳ]wANOG

1. u\ 140.116.44.0/255.255.255.0 P 140.116.79.0/255.255.255.0 oӺA 140.116.141.99 oӥDiHiJڭ̪ telnet AF
2. ~AL IP ױI

o˫hiH]w /etc/hosts.allow oɮצG
@

[root @test root]# vi /etc/hosts.allo telnetd:  140.116.44.0/255.255.255.0 : allow telnetd:  140.116.79.0/255.255.255.0 : allow telnetd:  140.116.141.99             : allow

@
AӡA]w /etc/hosts.deny yױzAG
@

[root @test root]# vi /etc/hosts.deny telnetd:  ALL     : deny

@
ALL NyzNIIܴΧaI򦳨Sw]wAҦpALH˧ڪ telnet port ɡAڴNNL IP OIHӪd߻P{ҤΡIAiHN /etc/hosts.deny oɮק令oӼˤlG
@

[root @test root]# vi /etc/hosts.deny telnetd: ALL : spawn (echo Security notice from host `/bin/hostname`; \ echo; /usr/sbin/safe_finger @%h ) | \ /bin/mail -s "%d-%h security" root & \ : twist ( /bin/echo -e "\n\nWARNING connection not allowed. Your attempt has been logged. \n\n\nĵiz|\nJAzsuN|QAåB@H᪺Ѧ\n\n ". )

@
bWҤlArry root zAiHgAӤHbΪ̨L e-mail AHKܤ֥H root nJ Linux DɡAeyDpAt~A̫XAY :twist ᪺X欰P@Cp@ӡAg\qյnJADɡA𫍧ùWN|ܤW̫@AåBNL IP H root ]Ϊ̬OAۤvHc^̥hI]GYǨSw tcp_wrappers M distribution AѩS safe_finger {AҥHLk\AoIٽЦh[`NOI^

nFA{b]zwgDF daemons ҰɮשmؿA]DFAȻP port AnpdߥثetΤWwgҰʤFAȩOHnAVFIwgǹLF ps P top ӭn|Τ~CIISAiHϥ ps P top ӧMwgҰʤFAȪ{ǻPL PID OILAڭ̫򪾹DӪAȱҰʪ port O@ӡHInDIiHϥ netstat oӺA[Oˬdڭ̪ port OIƦܥL]iHڭ̧ port {ǩO( PID )InFAڭ̴NӸլݬݳoӫOΪkaI

• netstat

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[root @test /root]# netstat [-r] [-i interface]  [root @test /root]# netstat [-antulp]  ѼƻG  -r  GܥX route NF  -i  GܥX interface eA ifconfig աI  -a  GܥXثeҦsuAI  -n  Gw]pAܥX host |H host name {AY n hiH port P host HƦr  -t  G tcp ʥ]su欰  -u  G udp ʥ]suA  -l  G LISTEN e  -p  GPܦ@su PID I(`NGu root ~Ϧ\I)  dҡG  [root @test /root]# netstat -r <==KKIܥXثeѪI  Kernel IP routing table  Destination     Gateway         Genmask         Flags   MSS Window  irtt Iface  140.116.141.253 *               255.255.255.255 UH       40 0          0 ppp0  192.168.1.0     *               255.255.255.0   U        40 0          0 eth0  192.168.0.0     *               255.255.255.0   U        40 0          0 eth0  127.0.0.0       *               255.0.0.0       U        40 0          0 lo  default         140.116.141.253 0.0.0.0         UG       40 0          0 ppp0  [root @test /root]# netstat -i eth0  <==ݬݩUܥXeAO_ ifconfig eth0 rIH  Kernel Interface table  Iface   MTU Met   RX-OK RX-ERR RX-DRP RX-OVR   TX-OK TX-ERR TX-DRP TX-OVR Flg  eth0   1500   077199373      0      0      169616342      0      0      0 BMRU  lo    16436   0 1130485      0      0      0 1130485      0      0      0 LRU  [root @test /root]# netstat -an  <==ܩҦsuAAåBHƦrA  [root @test /root]# netstat -tul<== LISTEN tcp P udp suAApUG  Active Internet connections (only servers)  Proto Recv-Q Send-Q Local Address           Foreign Address         State  tcp        0      0 *:mysql                 *:*                     LISTEN  tcp        0      0 *:netbios-ssn           *:*                     LISTEN  tcp        0      0 *:pop3                  *:*                     LISTEN  tcp        0      0 *:http                  *:*                     LISTEN  tcp        0      0 *:ftp                   *:*                     LISTEN  tcp        0      0 *:ssh                   *:*                     LISTEN  tcp        0      0 *:smtp                  *:*                     LISTEN  udp        0      0 *:netbios-ns            *:*  `NGW LISTEN ܸ port Owgb ť AȰաIӥ䪺 tcp O tcp ʥ]I  [root @test /root]# netstat -anp | more<==oӫOܱ`UFIаOoI

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netstat iOܤF_OA@wnǷ|IרLiHڭAѥثeADsuAIP}Ҫ port ǡIҥH@woǷ|~rIpGAOUFG
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netstat -a  | more
netstat -an | more
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@w|o{I_ǡH򦳪 port |HAȦW(ҦpWҤl̪ pop3 ...)|H port XܩOIHKKINO /etc/services H -n oӰѼƪγ~աIAiHo{OApG netstat -a ɡAܥXӪ port Xb /etc/services sbAȦW٪ɭԡAw]LN|ܥXӪAȦWٰաIOYb /etc/services 䤣ɮתܡA۵MN٬OH port XܪI[WF -n ѼƫAצpAL|H port IP ܰաI
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t~A -p ]ܦIרOb@DzW䧮suX{ɡAiH netstat Vanp | mored PID AMAHڭ̤eͨ쪺 tθ귽޲z AQ kill ӱ PID {ǡI ~Aϥ netstat Vtlp ]iHoثeb LISTEN port AȦW١AKKI˴NiHD port Oӵ{ǨӱҰʪIܫKQz?
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• ProtoGOʥ]Ϊ̬OqTwաI tcp , udp O`I
• Local AddressGaݪ IP P Port ApG /etc/services sbAȦW١ANHAȦWܡF
• Foreign Address Gť@ӦaϻP port F
• stateGACNܦhաI򥻪G
• LISTEN GYťA port I
• ESTABLISHEDGwإ߳susup
• TIME_WAITGӳsubثewgOݪAFIHɦi|_uI
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netstat iHdo۷hTIרb port ɡI]ڭnN ftp Anϥ ntsysv, chkconfig Hάݤ@U /etc/rc.d/rc.local Y]woIЪ`NAoӮɭԶȬONy}w]ҰzӤwAèSثeAȡA]zo{ ftp ٦bҰʪءAAnNLANG@

1. ϥ ntsysv chkconfig N wu-ftpd eŸF
2. XAH /etc/rc.d/init.d/xinet restart Ϊ̬O service xinet restart ӭsҰ xinet oӪAȡF
3. AH netstat -a | more ݤ@U ftp O_٦b LISTEN OH
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oˤ~OIPzioIn sshd HIKKIۤvլݬoI(`NGƹWAb Linux tΤAny}Y port zANOݭnyҰʩYӪAȡzաI]AAiHXY port AȡA{AȡAiӱҰʩLA򨺭ӸgѸӪAȦӱҰʪ port A۵MN|FI)

UO@ linux tΤW` daemons AjaiHѦҬݬI
 

AȦW	Ѽ w]ϥ port O_ݭn
anacron	/etc/anacrontab Sϥ port A Linux DäOѭԶ}ɭԡAo anacron NiHAby crontab zJwɶS檺u@I|ӨҤlӻAADbߤW 12:00 |۰AO crontab oӨҦʤu@Ob 4:00 u@AoӮɭԨҦʤu@OSܡHI anacron NiHϥΰաI pGDwg 24 pɶ}AӥBF cron Aoӵ{NݭnҰʤFC
apmd	/etc/sysconfig/apmd Sϥ port apmd O Adventage Power Management daemon YgAUWqAiHΨAѨtΪyqqqzApGⴣq~ݭnaڷQI 򥻤WAڭ̨ϥΪWΪ̬O@}AjPWݭnϥΦ@ daemonC
arpwatch	/etc/sysconfig/arpwatch Sϥ oOΨӫʴdy Hardware IP (MAC) P Software IP (TCP/IP IP) z daemonA٥iH e-mail qtκ޲zI @몺Dӻݭno daemon I
atd	/etc/at.allow, /etc/at.deny Sϥ port o`ӤͤFaINO@ϥΪҦʩROoIpGѰOFIhdݤ@UI oӳq`ݭnҰʰաILApGA@볣Oϥ cron AoӪF褣ҰʼvT]ܤjI
autofs	/etc/rc.d/init.d/autofs Sϥ port oӪFϥΦb۰ʱ@Ǹ˸m daemon ݭn}I
xinet chargen  chargen-udp	oFDn port O 19 F Dn\b󴣨ݥrNNaIڤ]O.... @ӻAαҰʰաI
crond	/etc/crontab Sϥ port ΨӰ ҦʩRO daemonI ȥҰI
xinet daytime  daytime-udp	oFϥ 13 port I Ψӧ@ daytime AȡAoO NTP (Network Time Protocol) W@NA تbiɶեu@CLA]L|psuL{𺢮ɶA åBOHWXǰeA]FSت~Aثewgܤ֨ϥγoNFI αҰ
xinet echo  echo-udp	ϥ port 7  αҰʰI
xinet finger	/etc/xinetd.d/finger port 79 ̤j\NOݪϥΪ̥iHdݥaݪϥΪ̸T ѩ󦳦wWU{ASnܡAnҰI
gpm	/etc/sysconfig/mouse Sϥ port brҦ̭iHϥ mouse ӱqơyƻsBKWBʴСz\I SnܡAijOyzI
httpd	/etc/httpd/conf/httpd.conf ϥ 80 port H() 443  oӴNOjW WWW DAȶ}Ҫ{աI ݧAݨDoI WWW hnҰʡI