ѬOݨ즳BͦbWszGyڪqڡIz٦_ǪOyڡIɳqɤqzDA oDDniHkwDPn]wDCw骺D·СA]ݭnzL@ǱM˸mӤRwF ܩn譱AjO]w~Ϊ̬O[~ӤwAnBz (ĥ|ͨ쪺NOnD)I OKIڭ̥Ӭݬݺb̥i|XDaI

6.1.1 wDGuB]ơBGu

bĤG¦ڭ̴ܦh¦A HΤ@²檺w@DCH@²檺PγsuӻAڭ̥iH]L[cpPUϩҥܡG

6.1-1BϰsuAܷN

bWϥܷA"Linux PC3" ns Internet WhܡAݭnzLuB洫B NAT D (Linux A IP ɾ)BADSL ƾھAqܽuBISP ۤvХ洫AH Internet WҦC] (]AѾBBLu)FǦai|XDڡH

uDG

bWϥܤAiHo{AP]ƤAϥγ̦hNOuաIn`NuuPu (RJ-45Y)AӨäOҦ]Ƴ䴩۰ʤuPu\઺I ҥHAnAѨA] (Hub/Switch/ƾھ) Ҥ䴩uFt~ApGAugL_BΪ̬OeWBA ܦiѩg`ʪWɭPqlT}AҥHAݭn`N@UoǨƱG
- uQI_F
- uLקᦱܧγyT}F
- ۻsY (p RJ-45 uY) ~褣}F
- YP] (p Hub) Ĳ}F
dBHub Router ]ƪDG

t~A٦@Ǻ]Ƥ]|DA`DpUG
- díwB~褣ΡAΪ̻PtΪۮeפ (d]O|a)F
- U]ƪYΡAĲ}AyTI (g`޴Nio)F
- ѩ]ƩҦbҴcH (ҦpL) ɭPD (g`DJ switch D)F
- U]ƨϥΤk}Ay]ƥ\I (switch ``q/_qea)F
]ưtmWhG

bUӳ]ƪtmWO@wWhAӳ̮eoͪDNOӪu|yTIA ɭPsuɶӪƦܵLksuCڭ̴b¦͹LAӺ̪䴩Z (10BASE5 ̪iF 500m)A ٦@ǨLCtmDAoG
- ϥο~uA̱`oͦbuPuO ({b֨oӰDF)I
- []uLAɭPTIYCҦpAӺ CAT5e uz׭פjOb 90 إk (M 10BASE5 iF 500m)AYӳ] (Hub/D) פj 90 خɡA۵MNeX{ToͰDFI
- LTzZA̱`oͦbuΪ̺]Ʈ𨷿ӱjϪiF
- ϰWA`IΪ̨L]ƤӦhALhڭ̱`Hҿת 543 hӻG(1)
  - 5 Ӻq (segment)Cҿ segment NbzsW̱񪺤@չqAb@ BNC q̭̦hu౵ 30 xqMBu`WL 185mC
  - 4 ӼWq (repeater)C]NONHj˸mC
  - 3 ӹqs (population)CoӤnzѡM]NOeһ 5 segment A u঳ 3 ӥiH˹qA䥦ӤC

WzO@ǳ̱`wDAMաAɭԬO]ƥNDAӧڭ̦b¦̭ͨ쪺ӫܭny Gu zpA]OyyγqP_n]oIҥHAwDP_xIC n㧐Uڭ̦AӲ@n]wDC

6.1.2 nDGIP ѼƳ]wBѳ]wBAȻP]w

ҿתnDAjNO IP ѼƳ]w~ڡAѤڡA٦ DNS IP ]w~A oǰDOݩn]wաIunN]w@AQΤ@ǰnd@dANDDXb̤FI򥻪DG

d IP/netmask ]w~G
ҦpGP@ IP bP@ӺqX{y IP ĬBlBn]w~BdXʵ{ϥο~Bd IRQB I/O Address ]wĬ𵥵F
ѪD (route table)G
̱`NOw] (default gateway) ]w~FIΪ̬OѤũҾɭPDA ϱoƫʥ]SkQeXhC
qTw۲G
̱`oͦbP@~tΤqTǿAҦp Windows 98 P Windows 2000 yڡz YnFqAh Windows 98 n[ NetBEUI oӳqTw~CSҦpⳡ Linux DnzL NFS qTwǿƮɡA䳣on䴩 portmap oӱҰ RPC w{~I oǳqTwڭ̳|b᭱`OЪաI
tD (loading)G
Pɦjqƫʥ]i Server Ϊ̬O Hub Ϊ̬OP@Ӻ줤A NiyyƦܱIIt~ApGϺHϥ BT (P2P n) Ϊ̬OHrɭPįΥRӰϺA]|yyDF
LDG
ҦpG@ port QצFAyLkYǺ귽Fε{ Bug DFε{ϥΪ̪]w~FHΤP@~tΪۮeʰDC

6.1.3 DBz

JMDoͤFANnhBzLڡIpBzOHHWPγsuϥܬҡAⴤӭhG

ѦۨҰ_AiHѦۨ PC Wdd_AuB Hub AƾھwˬdC boӨBJA̦nΪnNO ping AӧA̦n঳ⳡHWDӶisuաF
TwwSDFAAӫҳn骺]wDI

ڤWApGqɡAAiḨǳo˳BzG

AѰDGoӰDOo͡H٬O]eڰFʧ@ӾɭPLksuH ҦpegsL@Ӯ֤ߡAGӮ֤ߨäXʳsd...
T{ IPGݬݦۤvdLXʡH_oT IP ѼƨӳsuH
T{ϺsuGQ ping ӷqⳡD (Ѿ IP ɾ)ATwuP~ hub/switch u@`F
T{~suGݥD IP ɾ_̾ĥ|kQo IP ѼơAåH ping kTw~suOiH\ (Ҧp ping 168.95.1.1)F
T{ DNS dGQ nslookup host dig ˬd www.google.com ݬݡF
T{ Internet `IGiHQ traceroute ˬdU`IO_SDH
T{A`AGO_AuHΥLFH
T{ڤAGpGOOHsWڳoDAˬdDYǪAȥTҰʧ_HiQ netstat ˬdCάO_YǦwnS]wnAҦp SELinux oF
vDGO_ѩv]w~ҭPH O_ѩAѰOҥΥisufҭPHoӥiHzL tcpdump ӳBzI

zLoǳBzʧ@A@ӻAӳiHѨMALkWDFIMաApGOw骺DA򳾭]LkAA Ai̻ݭnO......yeקaĤlIz

JMDWwgͨ쪺XӤpIFAUӷMO@Ӥ@ӪLBzڡI Uڭ̴Non@B@}L}lˬdy{ڡI

6.2.1 BJ@Gdu@T{

A@XDɭԡAAӱqۤviHˬdaˬd_A]A ̭naNOˬdAdO_u@DաIˬddO_`u@kpUG

TwdwgXʦ\G
pGdSXʦ\ALAK͡IҥHAMݭnXʧAd~IT{dO_QXʡAiHQ lspci H dmesg oөNNӬd߬]ƻPҲժCԱаѦҡGĥ|C AjաAdXʵ{AFۤvsĶ~AAʶR@iKydIۥΡAOQkI
TwiHʪإ IP ѼơG
bQJdҲաAåByodNzAڭ̥iHQ ifconfig ip ӪӺd@Ӻ}լݬݡI ݯ_ IP ]wOHҦpG
[root@www ~]# ifconfig eth0 192.168.1.100
Ӫإ߸Ӻd IP AM᪽J ifconfig ݯ_d\]wnѼƧYiC pGiHإ߰_ IP ANH ping ˴ݬݡG
[root@www ~]# ping 192.168.1.100
pG^ܡAܳoӺd]wӬOSDFIAӫhO}l˴@UϰUӳswաI

6.2.2 BJGGϰUs]˴

bT{F̭nd]wAåBTwdO`AAۤUӫhOϰspFI]AO 6.1-1 ҳ]wPγsuϰ[cAAnDӡyzI

쪺G
_\[]XϺAP쪺IҥHAAnDҿת 192.168.1.0/24 oغ쪺F觋ҥNNqA BlBn (Netmask) Nq]oAѡCpGѰOFAЦ^hĤG¦A½@½C
Gateway P DNS ]wG
Gateway P DNS ̮eQdVoӨëDOgA Linux D IP IӬOng IP ɾ ( NAT D) IP b Gateway Ag 168.95.1.1 b DNS IP ]wIdڡI
Windows ݪu@sջPqWG
pAٻݭn귽ɡAANb windows tΤ}ɮפɡA åBĳҦqNyu@sաz]wۦPAyqW١zhۦPILAoӥuPڤ SAMBA AC

]AϺҦD IP ]wTFA򱵤UӧANiHϥ ping ӴըⳡϺDsuA oӳsuʧ@iHAըⳡDU]ơA]AuBHub/Switch NNI pGLkզ\ANAѤ@UG

IP ѼƬO_]wTG
AjաAMw IP/netmask O諸IbWҪɭԱ``o{PǵLksڪDWA @gϥ ifconfig ~o{L̻Pڪ IP bP@ӺqANO|o˪poͰڡI
suuDG
]Aڭ̫e쪺ulBL¶yTIDA t~AǤª Hub/Switch Ϊ̬O ADSL ƾھAѩS Auto MDI/MDIX \AҥHLk۰ʪuP_A AοuɭԡA]NLkqաIt~Aڭ̱``|A ²P_CDO_Qs Hub/Switch iHzLs Switch WOӧP_A LAѩ󦳮ɭԺuT}AMO٬O|GALNOLks Switch p (ۤvNo͹L)AɡABͭɤ@ OK uӴլݬݧaI
d Hub/Switch XDG
@Lkb~s쳾DAhìOIFAGĨDҦb줽ǹݡAxI DOnnI|LksuOH]O...Ǥҳq}A[W Switch ҦbBū׹LA [Wª switch ynzaFAINoˡy switch z bsҰ switch (ޱAWqu) N`FCҥHoAܦhpO|oͪA ӰϰҤ]ܮevTsu~ڡI

TwۤvD IP PdSDA[WϺzL ping ]չLSDAUӴNOnyoiH~su IP ѼơzաIoӭnI

6.2.3 BJTGoT IP Ѽ

syoT IP ѼơzڡHٰOoڭ̽͹LpGnQsW Internet ܡA niH public IP i淾q~AӻP public IP oqkAbxW` ADSL, Cable modem, ǳN, qܼCb CentOS Aڭ̥iHzLק /etc/sysconfig/network-scripts/ifcfg-eth0AΪ̬OQ rp-pppoe Ӷi漷A LצpAANOonsY ISP hNOF

bAT{ҦϺSDAѦҤ@Uĥ|СAsWAߧYH ifconfig ݬݦS쥿T IP ڡH bxWpGϥ ADSL suܡAAӥiHQo@եT Public IP ѼƪI

~ؤHBͨӫHAL̨ϥ ADSL ᳺMo@ Private IP A `L̨Sk[IL̷Qаݳo˪pO_XzCpGAxѬA M|DGyoMXzIzA]Ao IP uOFns ISP hӤwA ISP PADMiHzL Private IP ӳsuڡIpGOo˪ܡAAN֩wLk[FI ^_^

t~A̱`o{LkQo IP ~NOyBOOTPROTOzoӳ]wȳ]wFI] static P dhcp wҲͪ IP nDO@˪ڡIٰOoaInSOdb ifcfg-eth0 ̭]wѼƳIt~ApGAOϥ ADSL A OѬOLk\AĳAiHo˸լݬݡG

N ADSL ƾھAN Switch/Hub ]qF
RݤQAoǳ]ƤyD֡z@IAAsWqF
N Linux s ADSL d (] eth0) b ifcfg-eth0 AyONBOOTz]w noA sҰʺ (/etc/init.d/network restart)AMA adsl-start
pG٬OLk\AåBAwgT{SDAФعqHu{HABzaI

]ܦhɭԳOѩCLA]iD@ǺѼƦIDA ҥHAܴNnҰʺdA adsl-start ۰ʥhҰʺdYiI pGQo IP Ao٬OLkQs Internet WɡAAıo٦ǦaݭnBzOH

FקK switch H ADSL ƾھAHΤ@ǭ׺ϥΪ̪B͡ANRFWpqAtXwɾ (timer) өwɪVoӳ]Ƨj㬰ԣݭnwɾH]߹q@}۷|N...

6.2.4 BJ|GT{ѪWh

pGAwgQoT IP ѼƪܡA򱵤UӴNOդ@UO_iHsW Internet ڡI ĳAiHըϥ ping ӳss Hinet DNS DA]NO 168.95.1.1 աI

[root@www ~]# ping -c 3 168.95.1.1

pG^ANܧAy򥻤WwgSDAiHs Internet FIzA pGS^OHoFT IP oLks~DA֩wIISI ٰOoڭ̦b줺ƪǿiHzL MAC ӶǰeA pGbϺơAhݭnzLѡAרOӹw] (default route) ໼ʥ]aI ҥHApGA public IP Lks~ (Ҧp 168.95.1.1) Ai઺DNXbѻPWFC]ASҰʨADNYpѤUo ѪDpˬdHN route -n ˬdڡI

]Өϥ ADSL Linux DALѪpUAAıoXFDH

Destination     Gateway       Genmask         Flags Metric Ref    Use Iface
59.104.200.1    0.0.0.0       255.255.255.255 UH    0      0        0 ppp0
192.168.1.0     0.0.0.0       255.255.255.0   U     0      0        0 eth0
169.254.0.0     0.0.0.0       255.255.0.0     U     0      0        0 eth0
127.0.0.0       0.0.0.0       255.0.0.0       U     0      0        0 lo
0.0.0.0         192.168.1.2   0.0.0.0         UG    0      0        0 eth0

JӬݨWѿXAĤ@O ppp0 ͪ public IP AĤGO eth0 줶AAݨ̫@ 0.0.0.0/0.0.0.0 oӹw]ѡAMO쪺 eth0 gateway HXzA̤jDӬOXb ifcfg-eth0 ̭p߳]wFyGATEWAY=192.168.1.2z ҭPAѨMkG

ifcfg-eth0 GATEWAY=192.168.1.2 @A(ӦiX{b /etc/sysconfig/network )
sҰʺ /etc/init.d/network restart
si漷G adsl-stop; adsl-start

t~@ӥioͪpANOGyѰO]ww]ѡzաIҦpϥ ifconfig ʭs]wLd IP AѳWhO|QsAҥHw]ѥiN|FIӮɭԧANonQ route add ӼW[w]oI

6.2.5 BJGDWٻP IP dߪ DNS ~

pGAo{iH ping 168.95.1.1 o Internet WDAoLkϥsb}Cs http://www.google.com ܡA֩w 99% HWDOӦ۩ DNS ѪRxZIѨMkNO /etc/resolv.conf hݬݳ]wȹ藍ڡI@`eOo˪G

[root@www ~]# vim /etc/resolv.conf
nameserver 168.95.1.1
nameserver 139.175.10.20

̱`~Oy nameserver rgFIzuO̱`Dt~ApG client ݬO Windows tΩOH``Ǫ̷|daNOb windows ]wFIn`NGWindows ݪ DNS ]wPD /etc/resolv.conf eۦPYiIܦhǪ̳H TCP/IP DNS DOWۤv Linux DAoO諸 (DAۤv Linux W DNS A) IAunWA ISP A DNS D IP mNiHF

t~AC@D|DW (hostname) Aw]DWٷ|O localhost AoӥDWٷ|@ 127.0.0.1 IP b /etc/hosts CpGAgקLADW١AӥDW٫oLk@ӥT IP A ADb}ɡAi|nXQC ҥHoA /etc/hosts PADWٹA󤺳pӻAO۷n]wةOI

6.2.6 BJGLinux NAT A IP ɾXD

NAT A²檺\NO IP ɾաINAT D@wOѾAҥHAnb Linux W[nTѸTC_h֩wDCt~A NAT DW]wO_XzH IP ɾWO_]wתA|vT~suO_\DIC NAT Pڭ̷|b򪺳`~򤶲ЪաI

6.2.7 BJCGInternet D

Internet ]|XDIMաSFO|XDI|ҨӻAnX~exW詤]IuYA ɭPn_FluQ_AGɭP Internet yqj먮IoNO Internet D٦AƦ~e Study Area maIѩѾ]wXFItA GɭPsutתwCCoODXDAӬO Internet WYӸ`IXFpC QnT{O_DӦ Internet ܡANϥ traceroute aI dݰDOӦۨӦaAI

6.2.8 BJKGAD

pGWzBz OK AoLknJYDɡAڷQA̤jDNOX{bD]wաIo]AG

AèS}ӶAȡGҦpDF telnet AAϥ telnet hsuAOLksWաI
Dv]w~GҦpANYӥؿ]w drwx------ Aӥؿ֦̬ root A AoNӥؿ} WWW sAѩ WWW LkiJӥؿAҥHMLkTΤsڡI oǪ嫬v]w~pڡI
w]w~GҦp SELinux OΨӧӷLޥDs@خ֤߾AGAҰʪOtέ䴩A SELinux Ϧӥi|׸ӪAȪѡIӨLҦp /etc/hosts.deny, PAM ҲյA iyϥΪ̵LknJDIoNODAӬODysuLk\I
DG]w~]O@ӫܱ`DAAiHϥ tcpdump Ӱlܫʥ]yVA HQAѨO_]w~C

򥻤WA@ӺҪ˴u@iOTyNӥB``oAܦhg窥D ЧA``@yXhťťݤjagAh google ݬݤHaѨMkA UA󻴩ѨMDI ^_^I]NWzʧ@W@Ӭy{ϡAѦҬݬݡG

6.2-1BDѨMy{