ڭ̪Dbϰ̭DiHzLs觋Ӷiʥ]ǰeAbPqDQn۳suɡANonzLѾFC
OѾHLDn\OHUڭ̴NӲ@I
8.2.1 OѾP IP ɾ
JMDQnNƶǰe줣PɱozLѾAҥHաAѾDn\NOGyʥ]zoI]NOAѾ|Rӷݫʥ] IP YAbYXneFؼ IP AzLѾѪ (routing table) ӱNoӫʥ]VU@ӥؼ (next hop) ǰeCoNOѾ\C Ѿ\iHpFOHثeؤkiHFG
- w\GҦp Cisco, TP-Link, D-Link (2) qͲwѾA
oǸѾOJ@~tΡAiHtdP춡ʥ]ĶP\F
- n\GҦp Linux oӧ@~tΪ֤ߴNѫʥ]OC
ѾiHsPw]ơAåBiHĶܦhPʥ]榡Aq`...]KyڡI boӳ`̭Aڭ̨èSnQoNNAȰQbAӺY²檺Ѿ\G sӤPCKKIoӥ\ Linux ӤHqNiHFFIFOH
- }֤ߪʥ] (IP forward) \
NpPѪO Linux ֤ߥ\ҴѪAoʥ]O]O Linux ֤ߩҴѡA p[֤߬O_wgҰʫʥ]OH²ڡA[֤ߥ\ɮקYiApUҥܡG
[root@www ~]# cat /proc/sys/net/ipv4/ip_forward 0 <== 0 NSҰʡA 1 NҰʤF |
nɮתeܦҰʭ 1 ²檺ONOϥΡGyecho 1 > /proc/sys/net/ipv4/ip_forwardzYiC LAoӳ]wGbUs}N|ġC]Aijzקtγ]wɪeANO /etc/sysctl.conf ӹF}Ұʫʥ]\C
[root@www ~]# vim /etc/sysctl.conf # NUoӳ]wȭק勵TYiI (ӭȬ 0 ANאּ 1 Yi) net.ipv4.ip_forward = 1 [root@www ~]# sysctl -p <==ߨӳ]wͮ |
sysctl oӫOOb֤ߤu@ɥΨӪק֤߰Ѽƪ@ӫOAh\iHѦ man sysctl dߡC nháIunoӰʧ@AA Linux N㦳²檺Ѿ\FCӥѩ Linux ѾѪ]wkPAq`ѾWѪ觋NءG
- RAѡGH route oӫOӪ]wѪ֤ߥ\A]wȥunPҬ۲ŧYiC
LAA즳ܤƮɡAѾNons]wF
- ʺAѡGzL Quagga zebra n骺\AodzniHw˦b Linux ѾWA ӳodzniHʺA쪺ܤơAêק Linux ֤ߪѪTA ALʥH route ӭקAѪTI
AѤFѾAUӧAiݭnAѨ줰O NAT (Network Address Translation, }Ķ) AA NAT OԣH IP ɾNO²檺 NAT AաIKKAAѤFܡHSA NAT iHF IP ɪ\A NAT NO@ӸѾAuO NAT ѾhF@ӡy IP ഫz\COH
- @ӻAѾ|ӺAzLѾ IP \ӺiH۷qʥ]C
pGӤ@O@ IP (public IP) @Op IP (private IP) OH
ѩp IP ઽP@ IP qѸTAɴNonB~y IP Ķz\FF
- Linux NAT AiHzLקʥ] IP YƤӷΥؼ IP AӦۨp IP ʥ]iHন NAT A@ IP ANiHsW Internet I
ҥHAѾݪOO Public P Private IP ɡA~ݭn NAT \I NAT \ڭ̷|b`ɽͤΡAoӳ`Ƚͽפ@UѾӤwڡI ^_^
8.2.2 ɻݭnѾ
@ӻAqƶqpƤQp~OLѾAuݭnQ hub/switch 걵UqA MzL@us Internet WYiCLApGOWLƦʳqj~ҡA ѩL̪ҳq`ݭnҼ{pUpA]~ݭnѾ[]G
- uGuήįҶqG
b@ɤjӪPӼhn걵ҦqiIסAiHzLCӼӼh[]@ѾA ñNCӼӼhѾ۳sAN²檺zUӼhF ~ApGUӼhQ[]ѾAӬOHu걵UӼh hub/switch ɡA ѩP@쪺ƬOzLsӶǻAӤjӪY@qbsɡA ҦqN|H^AzI|yjӤįDFҥH[]ѾNujA NUo譱įF - WPO@ƪҶqG
b\ŪLĤGB¦AAN|oA unuOsb@_AƳzLsɡAANiHzL tcpdump OӺťʥ]ơA åBHѨҥHApGAƥiݭnWߡA Ϊ̬OYǭnƥnbq]HO@ɡAiHNǭnq@ӿWߪA B~[]BѾsWqC
ѾNuO@ӳ]ơAnpϥκݬݧAҪWIWȬO|X@ήרҡC Uڭ̥N[]@RAѪѾӪ@aI
8.2.3 RAѤѾ
]bQqҷAF@¾u@ιqOs~ѾӳsںA b٦@ӳݭnwWҡA]oWiOo˪pG
8.2-1BRAѤѾ[cܷN
HWϪ[cӻAoaqDn class C qAOOG
- @Ϻ(192.168.1.0/24) G]A Router A, PC1 H Linux Router TDҺcF
- O@(192.168.10.0/24)G]A Linux Router, PC2, PC3, PC4 DҺcC
𫟺 192.168.1.0/24 OΨӰ@usںΪAܩ 192.168.10.0/24 hOSΪCPC1 NO@uqA PC2 PC3, PC4 hOSu@ιqA Linux Router hOoӯSΨӳs줽q쪺ѾCbo˪[cUA ӯSʥ]NPqL@骺jFC
ѤWϧA]o{AunO㦳Ѿ\] (Router A, Linux Router) |㦳ӥHWA OΨӷqPAPɸӸѾ]|㦳@ӹw]ѰڡI ^_^I t~AA٥iH[W@Ǩ𪺳nb Linux Router WAHO@ PC2~PC4 qOI
ڭ̥ӱQ@UsunFAq PC2 oqͰ_CpG PC2 QnsW Internet ALsup|OpH
- o_suݨDGPC2 --> Linux Router --> Router A --> Internet
- ^suݨDGInternet --> Router A --> Linux Router --> PC2
[@Uⳡ Router ]wAnFWz\Ah Router A nӤA@ӬO~ Public IP @ӫhO鷺 Private IP A] IP OPA] Router A ٻݭnB~W[ NAT oӾ~AoӾڭ̦b`|~ͨC ~ARouter A äݭnB~]wCܩ Linux Router N²FIƳΧ@ANӺd]w IP A åBҰʮ֤ߪʥ]\AߨN[]FID`²Iڭ̴Nӽͤ@ͳoXӾ]waI
- Linux Router
boDݭnidAbo̱NLwqG
- eth0: 192.168.1.100/24
- eth1: 192.168.10.254/24
# 1. Bz eth0 [root@www ~]# vim /etc/sysconfig/network-scripts/ifcfg-eth0 DEVICE=eth0 BOOTPROTO=static IPADDR=192.168.1.100 NETMASK=255.255.255.0 GATEWAY=192.168.1.254 <==̭n]wڡIzLoDsXhI ONBOOT=yes # 2. ABz eth1 [root@www ~]# vim /etc/sysconfig/network-scripts/ifcfg-eth1 DEVICE=eth1 BOOTPROTO=none ONBOOT=yes IPADDR=192.168.10.254 NETMASK=255.255.255.0 # 3. Ұ IP [root@www ~]# vim /etc/sysctl.conf net.ipv4.ip_forward = 1 # Wz]wȡANw] 0 אּWz 1 YiIxs}hI [root@www ~]# sysctl -p [root@www ~]# cat /proc/sys/net/ipv4/ip_forward 1 <==oNOIInO 1 ~iHI # 4. sҰʺAåB[ѻP ping Router A [root@www ~]# /etc/init.d/network restart [root@www ~]# route -n Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 192.168.1.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0 192.168.10.0 0.0.0.0 255.255.255.0 U 0 0 0 eth1 169.254.0.0 0.0.0.0 255.255.0.0 U 0 0 0 eth1 0.0.0.0 192.168.1.254 0.0.0.0 UG 0 0 0 eth0 # WIb̫᭱ӸѾ]wO_TI [root@www ~]# ping -c 2 192.168.1.254 PING 192.168.1.254 (192.168.1.254) 56(84) bytes of data. 64 bytes from 192.168.1.254: icmp_seq=1 ttl=64 time=0.294 ms 64 bytes from 192.168.1.254: icmp_seq=2 ttl=64 time=0.119 ms <==^Yi |
²aIӥBzL̫᪺ ping ڭ̤]D Linux Router iHsW Router A oIo˧A Linux Router N OK FoIUӫhOn]w PC2 oӳQO@DoC
- O@AH PC2
קA PC2 O@ا@~tΡAAҳӬOo˪G
- IP: 192.168.10.20
- netmask: 255.255.255.0
- gateway: 192.168.10.254
H Linux @~tάҡAåB PC2 Ȧ eth0 @idɡAL]wOo˪G
[root@www ~]# vim /etc/sysconfig/network-scripts/ifcfg-eth0 DEVICE=eth0 BOOTPROTO=static IPADDR=192.168.10.20 NETMASK=255.255.255.0 GATEWAY=192.168.10.254 <==oӳ]w̭nաI ONBOOT=yes [root@www ~]# /etc/init.d/network restart [root@www ~]# route -n Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 192.168.10.0 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 0.0.0.0 192.168.10.254 0.0.0.0 UG 0 0 0 eth0 [root@www ~]# ping -c 2 192.168.1.254 |
̫@Ӱʧ@DI|s ping Sk ping Router A IP OHpGs ping Sk^ܡA ܧڭ̪suODIAq𫍧^suݨDy{Ӭݤ@UaI
- o_suGPC2 --> Linux Router (OK) --> Router A (OK)
- ^suGRouter A ( router A n^ؼЬO 192.168.10.20)ARouter A Ȧ public P 192.168.1.0/24 ѡA]ʥ]Ǩ Router A Aoӫʥ]N^ӤF...
o{FܡHOVAɫʥ]XhAOD`iAʥ]^ӡ㨺OHuni Router A ѳWhI 192.168.10.0/24 ɡAnNӫʥ] 192.168.1.100 NOFIҥHAno˶iC
- SOѳWhG Router A һݸ
]ڪ Router A ~d eth1 AӤ 192.168.1.254 hO]wb eth0 WYC b Router A W[@ѳWhOH²ڡIϥ route add hW[YiIpUҥܪpG
[root@www ~]# route add -net 192.168.10.0 netmask 255.255.255.0 \ > gw 192.168.1.100 |
LoӳWhä|gJ]wɡA]Us}oӳWhNFIҥHAAӭnإߤ@Ӹѳ]wɡC ѩoӸѬO̪b eth0 dWAҥH]wɪɦWӭnO route-eth0 Ioӳ]wɪeAڭ̭n]w 192.168.10.0/24 oӺ쪺 gateway O 192.168.1.100 ABOzL eth0 AgkN|ܦG
[root@www ~]# vim /etc/sysconfig/network-scripts/route-eth0 192.168.10.0/24 via 192.168.1.100 dev eth0 ؼк zLgateway ˸m [root@www ~]# route -n Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 120.114.142.0 0.0.0.0 255.255.255.192 U 0 0 0 eth1 192.168.1.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0 192.168.10.0 192.168.1.100 255.255.255.0 UG 0 0 0 eth0 169.254.0.0 0.0.0.0 255.255.0.0 U 0 0 0 eth1 0.0.0.0 120.114.142.254 0.0.0.0 UG 0 0 0 eth1 |
Wz[IbSX{ 192.168.10.0 ѡIpGܡA ping 192.168.10.20 ݬݯण^H MA PC2 Wh ping 192.168.1.254 ݬݦS^AAND]w\oInFAJMO@wgiHsW Internet FA O_N PC2 iHP@uAҦp PC1 isuOHڭ̨³zLѳWhӱQ@UA PC2 nsu PC1 ɡALsuVOo˪G
- suo_G PC2 --> Linux Router (OK) --> PC1 (OK)
- ^suG PC1 (suؼЬ 192.168.10.20 A]èSӸѳWhA]suᵹ default gateway AYO Router A) --> Router A (OK) --> Linux Router (OK) --> PC2
So{@ӫܥiRǿy{Hsuo_OSDաALOA^suM|zL Router A I oO] PC1 P쪺 Router A @ˡAäD 192.168.10.0/24 b 192.168.1.100 ̭աILAϥ Router A wgDFӺb Linux Router AҥHAӫʥ]٬OiHQ^ PC2 NOFC
- PC1 P PC2 zL Router A q觋
pGAQn PC1 onzL Router A ~su PC2 ܡANonP Router A ۦPAW[@ѳWhoI pGO Linux tΡApP Router A @˪]wpUG
[root@www ~]# vim /etc/sysconfig/network-scripts/route-eth0 192.168.10.0/24 via 192.168.1.100 dev eth0 [root@www ~]# /etc/init.d/network restart [root@www ~]# route -n Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 192.168.1.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0 192.168.10.0 192.168.1.100 255.255.255.0 UG 0 0 0 eth0 169.254.0.0 0.0.0.0 255.255.0.0 U 0 0 0 eth0 0.0.0.0 192.168.1.254 0.0.0.0 UG 0 0 0 eth0 |
̫un PC2 ϥ ping iHs PC1AP˪A PC1 ]iH ping PC2 ܡANܧA]wO OK աIdwIӳzLo˪]w觋AA]iHo{@ơANOGyѬOVAAnAѥXhѻP^ӮɪWhzC |ҨӻAbw]pU (Router A P PC1 SB~ѳ]w)Aʥ]OiH PC2 su PC1 AO PC1 oSѥiH^ PC2 ҥHWY~|nAb Router A Ϊ̬O PC1 W]wB~ѳWhڡIo˻AAFaH ^_^
Linux @@RAѪ Router ²aIHWרҨӻAAb Linux Router WXGS@B~u@AunN IP PnҰʡAM[W IP Forward \A A Linux ֤ߤ䴩ʥ]AMLu@̪ Linux kernel NDAdwFIuOn²I
Lo̥nOApGA Linux Router ]w𪺸ܡA ӥB٦]w NAT D IP ˧NAioSOdNA]٥i|yѻ~PD Wz Linux Router yèSϥΨ NAT \zISOLdNI
![m߰ʺAѩҳ]wsuܷN](/linux_server/0230router//router_dynamic.gif "m߰ʺAѩҳ]wsuܷN")
![bѾӤ䪺 IP ObP@Ӻ쪺]wp](/linux_server/0230router//arp_proxy.gif "bѾӤ䪺 IP ObP@Ӻ쪺]wp")
![`qQnǰe줺qhʥ]yV](/linux_server/0230router//arp_proxy_in.gif "`qQnǰe줺qhʥ]yV")
![qQnǰe쥿`ɪʥ]yV](/linux_server/0230router//arp_proxy_out.gif "qQnǰe쥿`ɪʥ]yV")