b}l Router eAڭ̥N@ӹdih IP ]wӧ@СAMAڨӻ Router []aI
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ݭnh IP H
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nn@dAݭnh IP OHDOSƧƧ@HIKKIڤSOoWAFSƧƧ@OHIh IP YǮɭԬO䥲nʪաIbɭԡyiz|ΪWOHo˻nF{bzϰAѩ󦳨ǪBͤ@}l]w~AG@ Hub oFӺAOO192.168.1.xx 192.168.0.xx AOzB̫ͭoSQܥL̪]wAoӮɭԫHy]P줧ƫʥ]ઽ۷qzoӷ٨SѰOaHIҥH 192.168.1.xx 192.168.0.xx NઽqoI]AzpGnP 192.168.1.xx qAz IP N]wbӺ줺AoӮɭԥt@Ӻ 192.168.0.xx ƫoSLkqFIҥHzNn``ܧ IP oIzSQ``ܧz IP AIoӮɭԦh IP NWγաIziHb@dWPɳ]w 192.168.0.xx 192.168.1.xx IP AphztΥiPɱӦ۳oӤP쪺ơIKI٤aI
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~A٦ܦhΪh IP aաIҦp Router ]wAɫ]|ϥΪ쪺It~AbըtΪɭԡA]``|ϥΨh IP ]wI򥻤WAh IP γ~٤ִNOFI
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p@H
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h IP b@dW]w²աINunOo@ӷNFANOɭd( Network Interface Card, NIC )Pɭ( Interface )@˪FI@ӬOɭA@ӫhOsuҲͪɭĄäۦPIO Interface ݭn[cb NIC ιڪC (pƾھ) W~InFIڭ̨ӽͤ@͹ڭaI
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pGzٰOo Linux Uw˸mOHɮרӥNܡANӪD Linux Ĥ@dN eth0 aHIOKIboӺdWĤ@ӵɭ( Interface )NOOHNO eth0:0 oIĤGӵɭh eth0:1 .....HInҰ eth0:0 ɡA eth0 ȥnQҰʡA eth0 ɡAҦ eth0:n ( n OƦrA0, 1....)N|QIoNOW쪺yɭO[cbɭWzNIIѩ]w觋DnSiHHy command line zʱҰʡA]iHϥΡy ˸m]wɮ zӳ]wIڭ̤OpUoI
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command line ʳ]wh IP G
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b Linux `ΫOg ̭ڭ̴g ifconfig iHΨӹFh IP ]w\ILDn]wykPdҬG

[root@test root]# ifconfig <device> <ip> netmask <nip> broadcast <bip> <action> ѼƻG <device>@@G˸mNAҦp eth0, eth0:0, eth0:1.... <ip>@@@@GӸ˸mN IP I netmask@@ GӸ˸mNlBn]wѼƦW <nip>@@@ GNOڪ netmask AҦp C Class h 255.255.255.0 boradcast@ Gs}]wѼ <bip>@@@ GYڪs} <action> @ Gʧ@IҦp up ҰʻP down I dҡG @ # 1. ק@ eth0 netmask Aѭ 255.255.255.0 ܦ 255.255.255.128 [root@test root]# ifconfig eth0 eth0      Link encap:Ethernet  HWaddr 00:50:FC:22:9C:57           inet addr:192.168.1.2  Bcast:192.168.1.255  Mask:255.255.255.0<=I           UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1           RX packets:5972569 errors:0 dropped:0 overruns:0 frame:0           TX packets:6263943 errors:0 dropped:0 overruns:0 carrier:0           collisions:1331 txqueuelen:100           RX bytes:557413197 (531.5 Mb)  TX bytes:2810197942 (2680.0 Mb)           Interrupt:10 Base address:0x6100 [root@test root]# ifconfig eth0 netmask 255.255.255.128 [root@test root]# ifconfig eth0 eth0      Link encap:Ethernet  HWaddr 00:50:FC:22:9C:57           inet addr:192.168.1.2  Bcast:192.168.1.255  Mask:255.255.255.128<=ק           UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1           RX packets:5972745 errors:0 dropped:0 overruns:0 frame:0           TX packets:6264165 errors:0 dropped:0 overruns:0 carrier:0           collisions:1331 txqueuelen:100           RX bytes:557431640 (531.6 Mb)  TX bytes:2810221471 (2680.0 Mb)           Interrupt:10 Base address:0x6100 [root @test /root]# ifconfig eth0 netmask 255.255.255.0<==էOo^ӡI @ 2. sW@Ӻɭ eth0:0 AӥBL IP 192.168.0.2 [root@test root]# ifconfig eth0:0 192.168.0.2 netmask 255.255.255.0 \ > broadcast 192.168.0.255 up [root@test root]# ifconfig eth0; ifconfig eth0:0 eth0      Link encap:Ethernet  HWaddr 00:50:FC:22:9C:57           inet addr:192.168.1.2  Bcast:192.168.1.255  Mask:255.255.255.0           UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1           RX packets:5973506 errors:0 dropped:0 overruns:0 frame:0           TX packets:6265264 errors:0 dropped:0 overruns:0 carrier:0           collisions:1331 txqueuelen:100           RX bytes:557511152 (531.6 Mb)  TX bytes:2810327518 (2680.1 Mb)           Interrupt:10 Base address:0x6100 eth0:0    Link encap:Ethernet  HWaddr 00:50:FC:22:9C:57           inet addr:192.168.0.2  Bcast:192.168.0.255  Mask:255.255.255.0           UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1           Interrupt:10 Base address:0x6100 ݡI²aIzɭNwg@XӤFIثez eth0 odWN 192.168.1.2 192.168.0.2 oӬɭsbFI~AoӳsuɭOϥΦP@ӹɭdIHHHݤ@UW HWaddr A eth0 P eth0:0 OϥΦP@ MAC OIٰOoܡHC@Ӻd@ӡyW@LGzw}AӴNO MAC OWܪ HWaddr IJMOϥΦP@ HWaddr AMNOӳsuɭϥΪOP@ӹɭoI @ ۫HܴNӴդ@UaI [root@test root]# ping -c 3 192.168.1.2; ping -c 3 192.168.0.2 PING 192.168.1.2 (192.168.1.2) from 192.168.1.2 : 56(84) bytes of data. 64 bytes from 192.168.1.2: icmp_seq=0 ttl=255 time=482 usec 64 bytes from 192.168.1.2: icmp_seq=1 ttl=255 time=188 usec 64 bytes from 192.168.1.2: icmp_seq=2 ttl=255 time=196 usec --- 192.168.1.2 ping statistics --- 3 packets transmitted, 3 packets received, 0% packet loss round-trip min/avg/max/mdev = 0.188/0.288/0.482/0.138 ms PING 192.168.0.2 (192.168.0.2) from 192.168.0.2 : 56(84) bytes of data. 64 bytes from 192.168.0.2: icmp_seq=0 ttl=255 time=289 usec 64 bytes from 192.168.0.2: icmp_seq=1 ttl=255 time=213 usec 64 bytes from 192.168.0.2: icmp_seq=2 ttl=255 time=203 usec --- 192.168.0.2 ping statistics --- 3 packets transmitted, 3 packets received, 0% packet loss round-trip min/avg/max/mdev = 0.203/0.235/0.289/0.038 ms @ 3. eth0:0 oӬɭ [root@test root]# ifconfig eth0:0 down

KKKKIp@ӡAzodWNwgӬɭաIOO 192.168.0.2 192.168.1.2 I²aILAo٬OIDANOC}zobʪJ@( Dg /etc/rc.d/rc.local oɮ׷ )AnFIUڭ̴NФ@UpH˸m]w觋ӳ]wh IP kaI
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˸m]wɳ]wh IPG
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oӪF]IٰOoڭ̦b sW Internet @AgdѼƳ]wɧaISINO /etc/sysconfig/network-scripts/ifcfg-eth0 oInFIڭ̥ثeOH˸m eth0:0 ˸mNA۵MɦWNݭn@աIҥHziHo˰@AӹFPW command line ]wۦPpI

[root@test root]# cd /etc/sysconfig/network-scripts [root@test network-scripts]# cp ifcfg-eth0 ifcfg-eth0:0 @@ Ъ`NA ifcfg ɦWOnA eth0:0 hO˸mNIҥHШ̱zݨDӳ]wɦWIҦpzn]w eth0:1 AhɦWӼg ifcfg-eth0:1 ~I @ 1. }l]wѼɡI [root@test network-scripts]# vi ifcfg-eth0:0 # This file is just to be used to test the more IPs DEVICE=eth0:0@@@@@@<==o̽иɦWag@ˡIY˸mNI ONBOOT=no@@@@@@@@<==O_}ɱҰʡIѩP馉AҥHAL @@@@@@@@@@@@@@o̳]wA}unҰ eth0 Aho̴N|QҰʡI BOOTPROTO=static@@@@ <==ϥΪ}]ww IPADDR=192.168.0.2@@@ <==ڳ]w IPI NETMASK=255.255.255.0@@<==NOlBn NETWORK=192.168.0.0@@@<==NO BROADCAST=192.168.0.255@<==NOs}աI @ 2. TҰʡI [root@test network-scripts]# ifup eth0:0 [root@test network-scripts]# ifconfig eth0:0 eth0:0    Link encap:Ethernet  HWaddr 00:50:FC:22:9C:57           inet addr:192.168.0.2  Bcast:192.168.0.255  Mask:255.255.255.0           UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1           Interrupt:10 Base address:0x6100 @ 3. TI [root@test network-scripts]# ifdown eth0:0

²aIo˴NiHFzh IP bP@dWؼoI
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ݭn`NaG
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@ӨAӤHOVyϥΰѼƳ]wɮת觋zӶiڪh IP ]wIo˦ܦhnBաI]AڥiHb ifcfg-eth0:0 oɮ׸YAH # ѲŸ᭱ӻ@UڬnظmoɮסAHΥiHϥɮתAAѤ@Uڪ]wɡAAӡAѩҦdѼɮ׳boӥؿUy /etc/sysconfig/network-scriptszAҥHڥiHܻN]woIҥHA˳oӤ觋ILAH@id]wh IP ݭnSOdNaG
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• ѩ eth0:n O̪b eth0 oӤWAҥH}ɭԡA eth0:n ̭]w ONBOOT Aun eth0 ]w ONBOOT=yesA}AҦP eth0 |QҰʰ_ӡAt~A eth0:n WQҰʡA eth0 @wnҰʤ~I

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• JMiH]wh IP AyqO_iHW[HI׬Oy_zA]WeOwAzdNO@AMLkW[yqFCҥH@id]wh IP ɡA IP NnbP@Ӻ줺FI

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O Router H
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ٰOoڭ̦b ¦ ̭LXӪFܡHyP쪺ƬyAݭnzL Router ĶzA]NOAڭ̥ݭnǥ router ӷqP줧ưաIq`ڭ̵o{ router aAObP줧ۤsq`IWAnFAڭ̤]o Router O@ӡyܶQzAI Linux iH router ܡHKKIܦnILiHI
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GѾP IP ɾ(Ϊ̬O Linux W[] Network Address Translation, NAT )OӤ@˪өNNAڭ̥ͫܰQ Router \(]\ӦhFIiHĶƫ~HAo̧ڭ̤ͳoǡI)Aª Router \uObq Router WӥHWƶǿAҥHbP쪺ƶǿɡANݭnzL Router FCLAo̯SOAjդ@UA@ IP P p IP OLkqAҥHU@zӤOO Public IPP Private IP ɡA² Router NLkNoӤƧ@qFI]Oؤ@˪ IP IoӮɭԴNݭnb Router Wҥ NAT \FCNAT ޳NiHNӦ Private IP ƫʥ]ANӷ ( M]iHקت ) IP ק令 NAT D Public IP Ӷi Internet ǰeIҥHA NAT DPɤ]O Router A~A]L㦳Nƫʥ]˪\AҥHiHzL NAT D Private IP ˫AӻP Internet Public IP ӷqIh NAT ޳Nڭ̦b򪺳`|AΡI
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ݭn Router H
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JM Router @άOsqPAڪqҦqunbP@Ӻ줧ANoFIڥNΤ Router ILAnѰOFڭ̦b ¦̭NVjaLyʥ]IzPy`I̤jǿqzI|ӨҤlӻnFG
@
• zqݭn 200 qnFAoӮɭ԰pz٬ONҦ 200 qLbP@Ӻ줧A@qnNƥXӪɭԡAKKIҦdN|y@ULzsIo|y۷jtI~Ab Hub YAҦƳbYy«Az|o{zƫܮe}lӵLksupIo|yjt....
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• γ\z|GypG Hub AڱNL Switch `iHFaI Switch OiHNʥ]Iv̧ܳCܡHzOIzSIOܤAzR Switch ӬO 10/100Mbps aIGMpܡAz Switch ̤jYɶǿq 12.5 MBytes kApGtz 200 qܡAC@WeOh֡H׬O 60 KBytes kIKIbϰqyq|oCHIר@ӤHRYqƪɭԡANGILHWeN|CI
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oӮɭԩγ\ Router \NiH{XoI򻡩OH]P줧ઽiƪqAҥHzݭnNO}ӡAӰ]H 200 q 5 ӺnFAoӮɭԤ@Ӻ̭u 40 qAboӱpUAGue( w 40 qӻ )AӥBѩ󤣦P줧|ۤzZAҥHzzs޿sɲͪypN|֫D`hIp@ӡAzϰyqνwAN۷jUqIyЯSOdNAq`jϰ( qƶqh~ )ApGW}Ahz~suɭԡA̤jtײ~ViӦ۩󤺳IoO] loading _~nyCܦhIz]sp( ҦpھF귽ɡBLɡBɮצAɵ )N|ɭPz Switch/Hub WeQΥFIz
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@뤣QnިƪޤHA̳wNGu]pUҼˡG
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@
o˰̤jnBNOy²zAzunޤ@ A NFILΥhzLAޥLʥ]IAϥz loading Ӥj]SYAikޤHӻALڥNho....oӮɭԱzyqiu|tܤjաIɡA۷ij]wUҼˡI
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@ o˦ӦnBաIzAWd(Ϊ̻OӤP쪺, Interface )AOtdPAѩoӺ줧j}ӤFA]ʥ]isɪy{HBʥ]IP Hub/Switch yqpN|νw@ǡIӨӤP줧ƤɩOHKKIhiHzLA[] Router \ӹFrIo˱ziHAѬݭn]woӼҼˤFaHI
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[PקѡG
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NpPeA Router ̤jγ~NONP쪺Ƥ۬yqAӭnqoǸơAMNݭnҿתy, routezoӪFFIHڪpҡAڬOH ADSL W Internet AOڦӤA192.168.1.0/24 o@ӤsbAҥHbڪ Linux UJ route ɡA|opUGG

[root@test root]# route Kernel IP routing table Destination     Gateway         Genmask         Flags Metric Ref    Use Iface 140.116.142.253 *               255.255.255.255 UH    0      0        0 ppp0 192.168.1.0     *               255.255.255.0   U     0      0        0 eth0 127.0.0.0       *               255.0.0.0       U     0      0        0 lo default         140.116.142.253 0.0.0.0         UG    0      0        0 ppp0

WܤNqOH²檺ANOG
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1. ڦ@ӫʥ]ne 192.168.1.0/24 oӺɡAڪX eth0 oӤF
2. ڦʥ]ne 127.0.0.0/8 ( A Class ) ɡAڪX lo oӤF
3. ڦƭne 140.116.142.253 ɡAѩLO p-p-p wAҥHOIIAӤ ppp0 oӡF
4. ܩLSWw쪺ҦAhΤ@ default o Gateway 140.116.142.253 A ppp0 XhIѩ ppp0 ǰe쪺o 140.116.142.253 O ISP AӤq` Router AҥHL|۰ʪNzʥ]AeeAϤ̫iHFتaI
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oAѤFܡH default Y Gateway iokܦhAҦpӦ ISP ѼơBb /etc/sysconfig/network-sysconfig/ifcfg-ethn oɮ׸̭]wѼơAH Cable Modem s ISP ҨoѼƵCOKI򰲳]z٦t~@ӤPA] 192.168.0.0/24 nFAӳoӺP˪Ob eth0 oӺdWAҥHznz eth0 P٭td 192.168.0.0/24 oӺɡAiHo˰I

[root@test root]# route add -net 192.168.0.0 netmask 255.255.255.0 dev eth0 [root@test root]# route Kernel IP routing table Destination     Gateway         Genmask         Flags Metric Ref    Use Iface 140.116.142.253 *               255.255.255.255 UH    0      0        0 ppp0 192.168.1.0     *               255.255.255.0   U     0      0        0 eth0 192.168.0.0     *               255.255.255.0   U     0      0        0 eth0 127.0.0.0       *               255.0.0.0       U     0      0        0 lo default         140.116.142.253 0.0.0.0         UG    0      0        0 ppp0 [root@test root]# route del -net 192.168.0.0 netmask 255.255.255.0 dev eth0

o˴NW[oILAoӮɭԩγ\ziHsWHaAOHaoLkszI]zèS 192.168.0.0/24 ̭@ IP AҥHOHq۵MLkPziƪyIoӮɭԴNnҰ Routing \աIpҰʩOH~ݤUhaI ^_^""

GЯSOdNAzϥ route ӨqXثeѪɡApGܪTD`wCAnháI@wa]w~CШ̷ route ܪTӭקzѼơIq`̮eo route Dab gateway ]wաIΪ̬OƱҰʦhɡA]|o˪pAҦpڴgݹLb route table WX{P@ӸѪA@THWIҦpW 192.168.0.0 .... @AYb route table WMƥX{TIo֩wDrIIBzkG
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1. NӬIϥ ifdown F
2. ϥ route \ANӸѧRI
3. קANŦXڭ̪ݨDI
4. sҰʤAë[ route I

nաIJMD Router nBAAӷMNOnӬ[]LoI[]ku²Izun@XӰʧ@NiHաI(GЯSOdNAȦb Routing \ӤwApGzbQqݭn[] Router ɡAiH̷ӥ媺Ӭ[]AOGuhݭnΡydzӰϹjAФnϥΥ媺 IP Alias 觋IOI)
@
1. ]wdAϳsPF
2. ]w route ѪAiHqF
3. Ұ ip_forward ﶵF
4. b Client ݳ]w gateway O server ݪ IP I
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ѩڭ̪ Router ݭnӺ줬۳sqAҥHoAz Router WNݭnPɨ㦳boӺ줧 IP I~Aѩ󤣦PݭnҰ Routing \IҥHzn@Ӱʧ@ANOثe Linux tθ̭ Routing \ҰʡIڭ̦b Linux pе -- ¦Dz߽g귽޲z 峹̭gLAӮ֤ߪ{dzOOb /proc̭Aܩڭ Linux ֤ߪ\hOb /proc/sys/net/ipv4 oӥؿIӱҰ Routing {Ǭ ip_forward oɮסIunNe]w 1 YҰʡAӷ 0 ɡANOաI]AYnҰ Routing hݭny echo 1 > /proc/sys/net/ipv4/if_forward zYiIUOڪҰաIЪ`NAoӽdҳ¶ȥuOb Router \}FIzӨ̷ӱzݨDӬ[]z Router INNڪsuϥܨqXoI ^_^
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һG
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bڪڴҷACӤ󪺤epUG
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1. Linux DGڪ Linux Aӥ@ NAT ΡA̭idA@is ADSL ƾھAoi~dN eth1 A@isAN eth0 F
2. Hub sqGLinux D鷺d eth0 s Hub WAPɡAHub W٦sbL|ӤHqAⳡӶiաA IP O 192.168.1.11 192.168.0.11 F
3. eth0 鷺dGѩ鷺 C Class AҥHڪd eth0 ]w 192.168.1.2 ӥt@ӵ eth0:0 ]w 192.168.0.2 I
4. Client ݪ@~tGڪ client ݪ]w譱Ab 192.168.1.11 ϥ Windows 2000 HA 192.168.0.11 hϥ Red Hat 7.3 oөNNoI
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򥻪ϥܦpUܷNG
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boӳ`Aڭ̤ͫ[] NAT DAӬO򳹸`~n쪺FAҥHJIab NAT Server 䤧]wA]NO eth0 ]wIYO쪺]wӤwI򥻤WAoӥiH ϰ[c @g峹eաIboӦaAڭ̪d IP I
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}l]wG
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ڭ̴NӵۤWBJ@B@BӧaI

1. ]wA𫟺 eth0 192.168.1.2, eth0:0 192.168.0.2 [root@test root]# cd /etc/sysconfig/network-scripts [root@test network-scripts]# vi ifcfg-eth0 DEVICE=eth0 ONBOOT=yes BOOTPROTO=static IPADDR=192.168.1.2 NETMASK=255.255.255.0 NETWORK=192.168.1.0 BROADCAST=192.168.1.255 GATEWAY=192.168.1.2 [root@test network-scripts]# vi ifcfg-eth0:0 DEVICE=eth0:0 ONBOOT=no BOOTPROTO=static IPADDR=192.168.0.2 NETMASK=255.255.255.0 NETWORK=192.168.0.0 BROADCAST=192.168.0.255 [root@test network-scripts]# ifup eth0 ; ifup eth0:0 [root@test network-scripts]# ifconfig eth0; ifconfig eth0:0 eth0      Link encap:Ethernet  HWaddr 00:50:FC:22:9C:57           inet addr:192.168.1.2  Bcast:192.168.1.255  Mask:255.255.255.0           UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1           RX packets:5975598 errors:0 dropped:0 overruns:0 frame:0           TX packets:6267765 errors:0 dropped:0 overruns:0 carrier:0           collisions:1331 txqueuelen:100           RX bytes:557835433 (531.9 Mb)  TX bytes:2811341821 (2681.1 Mb)           Interrupt:10 Base address:0x6100 eth0:0    Link encap:Ethernet  HWaddr 00:50:FC:22:9C:57           inet addr:192.168.0.2  Bcast:192.168.0.255  Mask:255.255.255.0           UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1           Interrupt:10 Base address:0x6100 @IҰʨӺdoIoӨSDաIiHsqӺoI 2. [ѱpG [root@test network-scripts]# route Kernel IP routing table Destination     Gateway         Genmask        Flags Metric Ref    Use Iface 140.116.142.253 *               255.255.255.255 UH    0      0        0 ppp0 192.168.1.0     *               255.255.255.0   U     0      0        0 eth0 192.168.0.0     *               255.255.255.0   U     0      0        0 eth0 127.0.0.0       *               255.0.0.0       U     0      0        0 lo default         140.116.142.253 0.0.0.0         UG    0      0        0 ppp0 KIѪO諸IβzL]SYOI 3. Ұ IP FORWARD ءG [root@test network-scripts]# echo 1 > /proc/sys/net/ipv4/ip_forward ۫HܡHMunWo@Aڭ̪ Linux N㦳 Router \FI ^_^ pG@ճQAziHNo@[J /etc/rc.d/rc.local oɮפI 4.1 ]w 192.168.1.0 Ӻ쪺 client qG IP:192.168.1.11 Gateway:192.168.1.2 <==׭n]wI netmask:255.255.255.0 network:192.168.1.0 broadcast:192.168.1.255 4.2 ]w 192.168.0.0 Ӻ쪺 Client q IP:192.168.0.11 Gateway:192.168.0.2 <==׭n]wI netmask:255.255.255.0 network:192.168.0.0 broadcast:192.168.0.255 p@ӡAӺ줧qN|zL GATEWAY Ө̪ GATEWAY b Linux WAҥH۵Mܮei淾qաIרڭ̤wg}ҤF Routing \IIOKISDI

o˴N]wFIpHܮeaIoˤ@ӡANiHzܦhq줧yqνwܦhoI~Ao̥X@IA]ڤWdҪNOnΨӧ@եΪAҥHd²AӥB٬ObP@ Linux DdWdwIЪ`NApGn[]jyq Router ɡAФOHidӤjPAoӷ|nOIӦܩ client ݪ]w譱iHѦҫeXGϰ]wPsW InternetC
@
t~AЯSOdNANpPeڭ̴LTӬݡA}ɭԡAױz alias ]w ( O_]w ONBOOT )AunҰ eth0 h eth0:n |QҰIoӮɭԽЯSOdNIpG𫟺@ IP alias ]w~ܡAiN|ɭPz鳣|qI]hbXb GATEWAY WIij]wAN eth0 shutdown AMAҰʡAYyifdown eth0; ifup eth0zMAӬݬ route pIo˥iHקKo]w\AU}oOqpoͪI
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Router u@G
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nFAiKUAڭ̥innnդ@Uڭ̪ router oIpթOH²rI
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1. b 192.168.1.11 o client ݡAsu 192.168.1.2 լݬݯ_suF
2. b 192.168.1.11 o client ݴլO_iHsu 192.168.0.2 o Server ݪt@ӺsF
3. b 192.168.1.11 o client ݴլO_iHst@ client ݡAY 192.168.0.11 o client IH
4. N Linux D /proc/sys/net/ipv4/ip_forward \AMAWTӨBJݬݡIլݬݺO_qOH
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ժu@NOo²Iӧaڭ̨ӴլݬݧaI

1. Client ݪ( Windows 2000 @~t, IP 192.168.1.11 )G C:\>ping 192.168.1.2  <==P쪺D Pinging 192.168.1.2 with 32 bytes of data: Reply from 192.168.1.2: bytes=32 time<10ms TTL=255 Reply from 192.168.1.2: bytes=32 time<10ms TTL=255 Reply from 192.168.1.2: bytes=32 time<10ms TTL=255 Reply from 192.168.1.2: bytes=32 time<10ms TTL=255 Ping statistics for 192.168.1.2:     Packets: Sent = 4, Received = 4, Lost = 0 (0% loss), Approximate round trip times in milli-seconds:     Minimum = 0ms, Maximum =  0ms, Average =  0ms C:\>ping 192.168.0.2  <==P쪺D Pinging 192.168.0.2 with 32 bytes of data: Reply from 192.168.0.2: bytes=32 time<10ms TTL=255 Reply from 192.168.0.2: bytes=32 time<10ms TTL=255 Reply from 192.168.0.2: bytes=32 time<10ms TTL=255 Reply from 192.168.0.2: bytes=32 time<10ms TTL=255 Ping statistics for 192.168.0.2:     Packets: Sent = 4, Received = 4, Lost = 0 (0% loss), Approximate round trip times in milli-seconds:     Minimum = 0ms, Maximum =  0ms, Average =  0ms C:\>ping 192.168.0.11  <==P쪺 Client ݡI Pinging 192.168.0.11 with 32 bytes of data: Reply from 192.168.0.11: bytes=32 time<10ms TTL=254 Reply from 192.168.0.11: bytes=32 time<10ms TTL=254 Reply from 192.168.0.11: bytes=32 time<10ms TTL=254 Reply from 192.168.0.11: bytes=32 time<10ms TTL=254 Ping statistics for 192.168.0.11:     Packets: Sent = 4, Received = 4, Lost = 0 (0% loss), Approximate round trip times in milli-seconds:     Minimum = 0ms, Maximum =  0ms, Average =  0ms ݨFܡHΧڭ̪ 192.168.1.11 iH ping 192.168.0.11 IOKoI 2. Server ݪקG [root@test root]# echo 0 > /proc/sys/net/ipv4/ip_forward N IP routing \@UIլݬݵGI 3. Client ݪ ( @~tά windows 2000, IP 192.168.1.11 )G C:\>ping 192.168.0.11 Pinging 192.168.0.11 with 32 bytes of data: Request timed out. Request timed out. Request timed out. Request timed out. Ping statistics for 192.168.0.11:     Packets: Sent = 4, Received = 0, Lost = 4 (100% loss), Approximate round trip times in milli-seconds:     Minimum = 0ms, Maximum =  0ms, Average =  0ms WNLksuFIܸرiaII ^_^ 4. _ Linux Router G [root@test root]# echo 1 > /proc/sys/net/ipv4/ip_forward nѰO IP Routing \[^өOI 5. Υt@ Linux Dݤ@UG ( IP 192.168.0.11 )G [root@vbird-redhat root]# ping -c 3 192.168.1.11 PING 192.168.1.11 (192.168.1.11) from 192.168.0.11 : 56(84) bytes of data. 64 bytes from 192.168.1.11: icmp_seq=1 ttl=127 time=0.542 ms 64 bytes from 192.168.1.11: icmp_seq=2 ttl=127 time=0.517 ms 64 bytes from 192.168.1.11: icmp_seq=3 ttl=127 time=0.541 ms --- 192.168.1.11 ping statistics --- 3 packets transmitted, 3 received, 0% loss, time 1998ms rtt min/avg/max/mdev = 0.517/0.533/0.542/0.022 ms ݨWrFܡHKKISIӤPT꦳bqoI ^_^

IժG]iDڭoISISҰ Routing \N|vT Linux O_iH㦳 Router OI

Wӽdҳ¥uOF@dҨӥܽdIn`NAڭ̦bq[] router ɭԡAq`OƱ歰CyqtAoӮɭԡAMONӺO}bӹdWnIӤOb@dW]w IP Ao˰CyqtUӤjIҥHAzutu譱inܦpUϩҥܪҼ( MA]w譱hO@˰աI )G

LצpAW觋iHѤ@Ǥp~AqƭnhhAS|vTyqpɡAiHϥΨӸѨMDIAӡA󤤤pǪGupOA]iHF줣CtĪGIӳo²檺 Router ziHϥ 486 صŪªqӬ[]NiHաIϥL loading S㦹~AW@gp{eijjaѦҡG
 

oˤlˬOIDCڪNOA@ˤΪܡA٬Oݭn˿WߪdjAouOϹjӤwAӥB٬OҼ{ʥ]yqɪDC @ zW[cAGuA linux u@idAҥHduɷ| hub WA aBb ݤPϬqq]Ou hubCoӧGu觋Aꩳhʥ]yqɡAaBb ݺ٬OiHAuL ip hݨ]OۤvϬqʥ]Ӥz|C @  ip alias ɾA@뤣ijΦb router/nat oP@ ip ϬqA]PϬqʥ]٬O|b@_... uӷ~ϥΤWAnrouter/nat \ɡAq`|ijϥ ip alias (DuO{ɻݭnΪ̬OuֺdiH)Aӷ|ϥΨidåBUۨϥ hub/switchζ}BzC @ t~H޲zںgӬݡAYOϥΪ̧@ǡAO a H[]dhcpA b ϥΪ̥iNDoF:Q ٦NOAYO a q@ǡA]iHۤv ip ]w b Ϭq ipAN|hϹjĥΡC

• dN eth0, eth1, eth2...AӲĤ@idĤ@ӵ eth0:0 ....C
• iHϥ ifconfig ӳ]wѼơA]iHϥνsɮסAɮצb /etc/sysconfig/network-scripts/ifcfg-ethn[:m]A𫟺 n P m ƦrF
• Linux n@ Router ɡAȥҰ ip_forwardF
• Router WӨ㦳ӥHWAHqPʥ]ơF
• ϥ route Oӳ]w Router ѪC
• ƹWARouter F@ഫ~Ab Router W[]Aib~AjXhӻݭnw (Security) ƪϹjI

• аݱzpNz eth0 oӤק令 192.168.100.2 b 192.168.100.0/25 ѼƤeH
• Фʳ]w eth0:1 oӵAϦѼơG 192.168.200.2, b 192.168.200.0/24C
• p[ѪH
• pҰ Linux IP Forward \H
• ]zO@ӾǮճ쪺T޲zAǮդ 200 qA^WjYNAnN 200 q 4 Subnet AаݱzӦpGu(еeXܷN)Hӳo 4 Subnet ѼƦp(Цۦ)HӬO_ݭn Router HpGݭnܡA]C Router ȯ঳Ӻ馉AӦpGuH(Gnϥε)
• U@zIyAo{iOWYӸ`IX{DAzӦpT{O@ Router XDH

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