在CISCO路由器上配置NAT功能.doc

在CISCO路由器上配置NAT功能随着internet的网络迅速发展，IP地址短缺已成为一个十分突出的问题。为了解决这个问题，出现了多种解决方案。下面几绍一种在目前网络环境中比较有效的方法即地址转换(NAT)功能。一、NAT简介NAT(Network Address Translation)的功能，就是指在一个网络内部，根据需要可以随意自定义的IP地址，而不需要经过申请。在网络内部，各计算机间通过内部的IP地址进行通讯。而当内部的计算机要与外部internet网络进行通讯时，具有NAT功能的设备（比如：路由器）负责将其内部的IP地址转换为合法的IP地址（即经过申请的IP地址）进行通信。二、NAT的应用环境情况1：一个企业不想让外部网络用户知道自己的网络内部结构，可以通过NAT将内部网络与外部Internet隔离开，则外部用户根本不知道通过NAT设置的内部IP地址。情况2：一个企业申请的合法Internet IP地址很少，而内部网络用户很多。可以通过NAT功能实现多个用户同时公用一个合法IP与外部Internet 进行通信。三、设置NAT所需路由器的硬件配置和软件配置：设置NAT功能的路由器至少要有一个内部端口（Inside），一个外部端口（Outside）。内部端口连接的网络用户使用的是内部IP地址。一般来说内、外部端口可以为任意指定。设置NAT功能的路由器的IOS应支持NAT功能(本文示例所用路由器为isco2811)。四、关于NAT的几个概念：内部本地地址（Inside local address）：分配给内部网络中的计算机的内部IP地址。内部合法地址（Inside global address）：对外进入IP通信时，代表一个或多个内部本地地址的合法IP地址。需要申请才可取得的IP地址。五、CISCO路由器NAT的设置方法：CISCO各种型号路由器NAT设置方法及命令基本相同。NAT设置可以分为静态地址转换、动态地址转换、复用动态地址转换。1、静态地址转换适用的环境静态地址转换将内部本地地址与内部合法地址进行一对一的转换，且需要指定和哪个合法地址进行转换。如果内部网络有E-mail服务器或FTP服务器等可以为外部用户提供的服务，这些服务器的IP地址必须采用静态地址转换，以便外部用户可以使用这些服务。静态地址转换基本配置步骤：（1）、在内部本地地址与内部合法地址之间建立静态地址转换。在全局设置状态下输入：Ipnatinsidesourcestatic内部本地地址内部合法地址（2）、指定连接网络的内部端口，在端口设置状态下输入：ipnatinside（3）、指定连接外部网络的外部端口，在端口设置状态下输入：ipnatoutside注：可以根据实际需要定义多个内部端口及多个外部端口。CISCO2811配置NAT静态地址转换实例：本实例实现静态NAT地址转换功能。将2811的FastEthernet0/0作为外部端口，FastEthernet0/1作为内部端口。其中0，1，2的内部本地地址采用静态地址转换，其内部合法地址分别对应为0，1，2。路由器2811的配置：route2811#show runBuilding configuration.Current configuration : 6564 bytes!version 12.4service timestamps debug datetime msecservice timestamps log datetime msecno service password-encryption!hostname route2811!boot-start-markerboot-end-marker!logging buffered 4096 errorsenable secret 5 $1$Ihwd$HMLrd7gHvZGC4YHCBVPx5/!no aaa new-model!resource policy!network-clock-participate wic 0ip subnet-zero!ip cefno ip dhcp use vrf connectedip dhcp excluded-address 53!ip dhcp pool ipphone import all network option 150 ip 53 default-router 53 lease infinite!ip domain name isdn switch-type primary-qsigcarrier-id Word!voice-card 0 no dspfarm!voice service voip allow-connections h323 to h323 allow-connections h323 to sip allow-connections sip to h323 allow-connections sip to sip!voice service vofr modem passthrough codec g711alaw!fax receive called-subscriber $d$fax send transmitting-subscriber $s$fax interface-type fax-mail!crypto pki trustpoint TP-self-signed-2758260478 enrollment selfsigned subject-name cn=IOS-Self-Signed-Certificate-2758260478 revocation-check none rsakeypair TP-self-signed-2758260478!crypto pki certificate chain TP-self-signed-2758260478 certificate self-signed 01 30820250 308201B9 A0030201 02020101 300D0609 2A864886 F70D0101 04050030 31312F30 2D060355 04031326 494F532D 53656C66 2D536967 6E65642D 43657274 69666963 6174652D 32373538 32363034 3738301E 170D3036 31313232 31303037 32365A17 0D323030 31303130 30303030 305A3031 312F302D 06035504 03132649 4F532D53 656C662D 5369676E 65642D43 65727469 66696361 74652D32 37353832 36303437 3830819F 300D0609 2A864886 F70D0101 01050003 818D0030 81890281 8100DADB C8FCB691 746A5E19 79893333 CC2E4456 7FC5D2C7 042AC16E 590E9560 A99DF8FA A91867B8 08E07457 5A4ACF03 6680D6DF 8DD3D590 D2B77E5A FEC8E34C 84C163B5 15C1DA39 11F9B232 28D59FB9 0BCE9797 BBD9E828 D48BE2E0 6D3DB65E 55563485 AB0B5347 7E857EA0 4A4231B1 CCC657B6 EB5CA8AE 0E0283C1 CC4F4A5A 9DC50203 010001A3 78307630 0F060355 1D130101 FF040530 030101FF 30230603 551D1104 1C301A82 18726F75 74653238 31312E79 6F757264 6F6D6169 6E2E636F 6D301F06 03551D23 04183016 8014E139 8B107691 812F740D 43C8AEC5 9B7B4C39 9829301D 0603551D 0E041604 14E1398B 10769181 2F740D43 C8AEC59B 7B4C3998 29300D06 092A8648 86F70D01 01040500 03818100 5547F983 45F6A28F E43E5D6E 9B0700EA FFC0E779 9D7DA745 029DBFEA 12DD3749 CACE92A9 DBC184AC 47E21EA2 57A05EDD 9FB762E6 374CE282 E120BB07 F0CFAA99 11767EB7 488ECF19 D7FF8F85 B9F058CC 6D35ECF3 20A2AA53 737AB8D8 B03E040D A15538AD 33F96B5B F0FDBB05 12153132 03FEA945 F0F431C1 4322F9FB 10766C54 quitusername dengyg privilege 15 secret 5 $1$/NYs$eZP61fvI7zabpi1xBalW0.username admincisco privilege 15 view root secret 5 $1$CKgk$IuL1hXtwRCggI38b1spau0!controller E1 0/0/0 framing NO-CRC4 clock source internal line-termination 75-ohm pri-group timeslots 1-16!interface FastEthernet0/0 ip address 20 ip nat outside /指定连接网络的外部端口 duplex auto speed auto no cdp enable!interface FastEthernet0/1 ip address 20 ip nat inside /指定连接网络的内部端口 duplex auto speed auto!interface Serial0/0/0:15 no ip address isdn switch-type primary-qsig isdn incoming-voice voice!interface Dialer0 no ip address!ip classless!ip http serverip http authentication localip http secure-serverip http timeout-policy idle 60 life 86400 requests 10000ip nat inside source static 0 0 /在内部本地地址与内部合法地址之间建立静态地址转换ip nat inside source static 1 1 /在内部本地地址与内部合法地址之间建立静态地址转换ip nat inside source static 2 2 /在内部本地地址与内部合法地址之间建立静态地址转换!tftp-server flash:P00303020214.bintftp-server flash:P00403020214.bin!control-plane!voice-port 0/0/0:15 cptone CN!dial-peer cor custom!dial-peer voice 2000 pots destination-pattern 83. port 0/0/0:15!dial-peer voice 3000 voip destination-pattern 38. session protocol sipv2 session target ipv4: session transport udp codec g729br8 fax protocol pass-through g711alaw!gateway timer receive-rtp 1200!telephony-service load 7960-7940 P00403020214 max-ephones 20 max-dn 30 ip source-address 53 port 2000 auto assign 1 to 4 max-conferences 8 gain -6 call-forward pattern .T call-forward pattern 6000 transfer-system full-consult transfer-pattern .T!ephone-dn 1 number 8001!ephone 1 keepalive 10 mac-address 0019.E7A1.6BAB speed-dial 1 +99111 label mydial1 speed-dial 2 +99222 label mydial2 type 7940 button 1:1!banner login C-Cisco Router and Security Device Manager (SDM) is installed on this device.This feature requires the one-time use of the username ciscowith the password cisco. The default username and password have a privilege level of 15.Please change these publicly known initial credentials using SDM or the IOS CLI.Here are the Cisco IOS commands.username privilege 15 secret 0 no username ciscoReplace and with the username and password you want to use.For more information about SDM please follow the instructions in the QUICK STARTGUIDE for your router or go to /go/sdm-C!line con 0 password cisco loginline aux 0line vty 0 4 privilege level 15 password cisco login local transport input telnet sshline vty 5 15 privilege level 15 login local transport input telnet ssh!scheduler allocate 20000 1000!End配置完成后可以用以下语句进行查看：showipnatstatistcsshowipnattranslations2、动态地址转换适用的环境：动态地址转换也是将本地地址与内部合法地址一对一的转换，但是动态地址转换是从内部合法地址池中动态地选择一个末使用的地址对内部本地地址进行转换。动态地址转换基本配置步骤：（1）、在全局设置模式下，定义内部合法地址池ipnatpool地址池名称起始IP地址终止IP地址子网掩码注：其中地址池名称可以任意设定。（2）、在全局设置模式下，定义一个标准的access-list规则以允许哪些内部地址可以进行动态地址转换。Access-list标号permit源地址通配符注：其中标号为1-99之间的整数。（3）、在全局设置模式下，将由access-list指定的内部本地地址与指定的内部合法地址池进行地址转换。 ipnatinsidesourcelist访问列表标号pool 内部合法地址池名字（4）、指定与内部网络相连的内部端口，在端口设置状态下：ipnatinside（5）、指定与外部网络相连的外部端口，在端口设置状态下： ipnatoutsideCISCO2811配置动态NAT地址转换实例：将2811的FastEthernet0/0作为外部端口，FastEthernet0/1作为内部端口。其中网段采用动态地址转换，对应内部合法地址分别对应为0，1，2。路由器2811的配置：route2811#show runBuilding configuration.Current configuration : 6546 bytes!version 12.4service timestamps debug datetime msecservice timestamps log datetime msecno service password-encryption!hostname route2811!boot-start-markerboot-end-marker!logging buffered 4096 errorsenable secret 5 $1$Ihwd$HMLrd7gHvZGC4YHCBVPx5/!no aaa new-model!resource policy!network-clock-participate wic 0ip subnet-zero!ip cefno ip dhcp use vrf connectedip dhcp excluded-address 53!ip dhcp pool ipphone import all network option 150 ip 53 default-router 53 lease infinite!ip domain name isdn switch-type primary-qsigcarrier-id Word!voice-card 0 no dspfarm!voice service voip allow-connections h323 to h323 allow-connections h323 to sip allow-connections sip to h323 allow-connections sip to sip!voice service vofr modem passthrough codec g711alaw!fax receive called-subscriber $d$fax send transmitting-subscriber $s$fax interface-type fax-mail!crypto pki trustpoint TP-self-signed-2758260478 enrollment selfsigned subject-name cn=IOS-Self-Signed-Certificate-2758260478 revocation-check none rsakeypair TP-self-signed-2758260478!crypto pki certificate chain TP-self-signed-2758260478 certificate self-signed 01 30820250 308201B9 A0030201 02020101 300D0609 2A864886 F70D0101 04050030 31312F30 2D060355 04031326 494F532D 53656C66 2D536967 6E65642D 43657274 69666963 6174652D 32373538 32363034 3738301E 170D3036 31313232 31303037 32365A17 0D323030 31303130 30303030 305A3031 312F302D 06035504 03132649 4F532D53 656C662D 5369676E 65642D43 65727469 66696361 74652D32 37353832 36303437 3830819F 300D0609 2A864886 F70D0101 01050003 818D0030 81890281 8100DADB C8FCB691 746A5E19 79893333 CC2E4456 7FC5D2C7 042AC16E 590E9560 A99DF8FA A91867B8 08E07457 5A4ACF03 6680D6DF 8DD3D590 D2B77E5A FEC8E34C 84C163B5 15C1DA39 11F9B232 28D59FB9 0BCE9797 BBD9E828 D48BE2E0 6D3DB65E 55563485 AB0B5347 7E857EA0 4A4231B1 CCC657B6 EB5CA8AE 0E0283C1 CC4F4A5A 9DC50203 010001A3 78307630 0F060355 1D130101 FF040530 030101FF 30230603 551D1104 1C301A82 18726F75 74653238 31312E79 6F757264 6F6D6169 6E2E636F 6D301F06 03551D23 04183016 8014E139 8B107691 812F740D 43C8AEC5 9B7B4C39 9829301D 0603551D 0E041604 14E1398B 10769181 2F740D43 C8AEC59B 7B4C3998 29300D06 092A8648 86F70D01 01040500 03818100 5547F983 45F6A28F E43E5D6E 9B0700EA FFC0E779 9D7DA745 029DBFEA 12DD3749 CACE92A9 DBC184AC 47E21EA2 57A05EDD 9FB762E6 374CE282 E120BB07 F0CFAA99 11767EB7 488ECF19 D7FF8F85 B9F058CC 6D35ECF3 20A2AA53 737AB8D8 B03E040D A15538AD 33F96B5B F0FDBB05 12153132 03FEA945 F0F431C1 4322F9FB 10766C54 quitusername dengyg privilege 15 secret 5 $1$/NYs$eZP61fvI7zabpi1xBalW0.username admincisco privilege 15 view root secret 5 $1$CKgk$IuL1hXtwRCggI38b1spau0!controller E1 0/0/0 framing NO-CRC4 clock source internal line-termination 75-ohm pri-group timeslots 1-16!interface FastEthernet0/0 ip address 20 ip nat outside /指定连接网络的外部端口 duplex auto speed auto no cdp enable!interface FastEthernet0/1 ip address 20 ip nat inside /指定连接网络的内部端口 duplex auto speed auto!interface Serial0/0/0:15 no ip address isdn switch-type primary-qsig isdn incoming-voice voice!interface Dialer0 no ip address!ip classless!ip http serverip http authentication localip http secure-serverip http timeout-policy idle 60 life 86400 requests 10000ip nat pool abc 0 2 netmask /定义内部合法地址池ip nat inside source list 1 pool abc /将由access-list指定的内部本地地址与指定的内部合法地址池进行地址转换!access-list 1 permit 55 /定义一个标准的access-list规则以允许哪些内部地址可以进行动态地址转换!tftp-server flash:P00303020214.bintftp-server flash:P00403020214.bin!control-plane!voice-port 0/0/0:15 cptone CN!dial-peer cor custom!dial-peer voice 2000 pots destination-pattern 83. port 0/0/0:15!dial-peer voice 3000 voip destination-pattern 38. session protocol sipv2 session target ipv4: session transport udp codec g729br8 fax protocol pass-through g711alaw!dial-peer voice 20 pots destination-pattern 020. port 0/0/0:15!dial-peer voice 4000 voip destination-pattern 6. session target ipv4:0 codec g723ar63!gateway timer receive-rtp 1200!telephony-service load 7960-7940 P00403020214 max-ephones 20 max-dn 30 ip source-address 53 port 2000 auto assign 1 to 4 max-conferences 8 gain -6 call-forward pattern .T call-forward pattern 6000 transfer-system full-consult transfer-pattern .T!ephone-dn 1 number 8001!ephone 1 keepalive 10 mac-address 0019.E7A1.6BAB speed-dial 1 +99111 label mydial1 speed-dial 2 +99222 label mydial2 type 7940 button 1:1!banner login C-Cisco Router and Security Device Manager (SDM) is installed on this device.This feature requires the one-time use of the username ciscowith the password cisco. The default username and password have a privilege level of 15.Please change these publicly known initial credentials using SDM or the IOS CLI.Here are the Cisco IOS commands.username privilege 15 secret 0 no username ciscoReplace and with the username and password you want to use.For more information about SDM please follow the instructions in the QUICK STARTGUIDE for your router or go to /go/sdm-C!line con 0 password cisco loginline aux 0line vty 0 4 privilege level 15 password cisco login local transport input telnet sshline vty 5 15 privilege level 15 login local transport input telnet ssh!scheduler allocate 20000 1000!end 3、复用动态地址转换适用的环境：复用动态地址转换首先是一种动态地址转换，但是它可以允许多个内部本地地址共用一个内部合法地址。只申请到少量IP地址但却经常同时有多于合法地址个数的用户上外部网络的情况，这种转换极为有用。注意：当多个用户同时使用一个IP地址，外部网络通过路由器内部利用上层的如TCP或UDP端口号等唯一标识某台计算机。复用动态地址转换配置步骤：（1）、在全局设置模式下，定义内部合地址池ipnatpool地址池名字起始IP地址终止IP地址子网掩码注：其中地址池名字可以任意设定。（2）、在全局设置模式下，定义一个标准的access-list规则以允许哪些内部本地地址可以进行动态地址转换。access-list标号permit源地址通配符注：其中标号为199之间的整数。（3）、在全局设置模式下，设置在内部的本地地址与内部合法IP地址间建立复用动态地址转换。ipnatinsidesourcelist访问列表标号pool内部合法地址池名字overload（4）、在端口设置状态下，指定与内部网络相连的内部端口ipnatinside（5）、在端口设置状态下，指定与外部网络相连的外部端口ipnatoutsideCISCO2811配置动态NAT地址转换实例：将2811的FastEthernet0/0作为外部端口，FastEthernet0/1作为内部端口。其中网段采用复用动态地址转换，假设企业只申请了一个合法的IP地址0。路由器2811的配置：route2811#show runBuilding configuration.Current configuration : 6555 bytes!version 12.4service timestamps debug datetime msecservice timestamps log datetime msecno service password-encryption!hostname route2811!boot-start-markerboot-end-marker!logging buffered 4096 errorsenable secret 5 $1$Ihwd$HMLrd7gHvZGC4YHCBVPx5/!no aaa new-model!resource policy!network-clock-participate wic 0ip subnet-zero!ip cefno ip dhcp use vrf connectedip dhcp excluded-address 53!ip dhcp pool ipphone import all network option 150 ip 53 default-router 53 lease infinite!ip domain name isdn switch-type primary-qsigcarrier-id Word!voice-card 0 no dspfarm!voice service voip allow-connections h323 to h323 allow-connections h323 to sip allow-connections sip to h323 allow-connections sip to sip!voice service vofr modem passthrough codec g711alaw!fax receive called-subscriber $d$fax send transmitting-subscriber $s$fax interface-type fax-mail!crypto pki trustpoint TP-self-signed-2758260478 enrollment selfsigned subject-name cn=IOS-Self-Signed-Certificate-2758260478 revocation-check none rsakeypair TP-self-signed-2758260478!crypto pki certificate chain TP-self-signed-2758260478 certificate self-signed 01 30820250 308201B9 A0030201 02020101 300D0609 2A864886 F70D0101 04050030 31312F30 2D060355 04031326 494F532D 53656C66 2D536967 6E65642D 43657274 69666963 6174652D 32373538 32363034 3738301E 170D3036 31313232 31303037 32365A17 0D323030 31303130 30303030 305A3031 312F302D 06035504 03132649 4F532D53 656C662D 5369676E 65642D43 65727469 66696361 74652D32 37353832 36303437 3830819F 300D0609 2A864886 F70D0101 01050003 818D0030 81890281 8100DADB C8FCB691 746A5E19 79893333 CC2E4456 7FC5D2C7 042AC16E 590E9560 A99DF8FA A91867B8 08E07457 5A4ACF03 6680D6DF 8DD3D590 D2B77E5A FEC8E34C 84C163B5 15C1DA39 11F9B232 28D59FB9 0BCE9797 BBD9E828 D48BE2E0 6D3DB65E 55563485 AB0B5347 7E857EA0 4A4231B1 CCC657B6 EB5CA8AE 0E0283C1 CC4F4A5A 9DC50203 010001A3 78307630 0F060355 1D130101 FF040530 030101FF 30230603 551D1104 1C301A82 18726F75 74653238 31312E79 6F757264 6F6D6169 6E2E636F 6D301F06 03551D23 04183016 8014E139 8B107691 812F740D 43C8AEC5 9B7B4C39 9829301D 0603551D 0E041604 14E1398B 10769181 2F740D43 C8AEC59B 7B4C3998 29300D06 092A8648 86F70D01 01040500 03818100 5547F983 45F6A28F E43E5D6E 9B0700EA FFC0E779 9D7DA745 029DBFEA 12DD3749 CACE92A9 DBC184AC 47E21EA2 57A05EDD 9FB762E6 374CE282 E120BB07 F0CFA