Linux
Linux 拆分訪問（帶負載平衡的多個 Internet 連接）
短篇小說：我手上有一個故障的 cisco 1811。這是一個雙WAN固定配置路由器。我用路由圖設置它來進行負載平衡。它可以工作，但每隔幾個小時它就會自己拉屎，需要重新啟動。我需要把它從它在網路上的目前位置中刪除。
所以我所做的（出於臨時目的）是建立一個新盒子，安裝debian，iproute2並配置iptables。
我有兩個網際網路連接，都在不同的電話線上，都連接到單獨的 linksys 路由器。路由器處於橋接模式。新盒子有 3 個 NICS（2 個 nics 用於以橋接模式連接到每個路由器）和一個用於內部網路。我使用 pppoeconf 設置了兩個新的 pppoe 連接。這一切都有效。
當只有一個連接啟動時，它似乎可以工作，但當兩個連接都啟動時就不行。我有一種感覺，它不知道在哪個介面上處理數據包。我已經閱讀了許多關於拆分訪問和負載平衡的文件，但我無法讓它工作。
gateway:~# ifconfig -a eth1 Link encap:Ethernet HWaddr 00:24:8c:4e:31:e7 inet addr:192.168.5.254 Bcast:192.168.5.255 Mask:255.255.255.0 inet6 addr: fe80::224:8cff:fe4e:31e7/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:3494 errors:0 dropped:0 overruns:0 frame:0 TX packets:3553 errors:0 dropped:0 overruns:0 carrier:1 collisions:0 txqueuelen:1000 RX bytes:633209 (618.3 KiB) TX bytes:1668656 (1.5 MiB) Interrupt:219 eth2 Link encap:Ethernet HWaddr 00:40:f4:ba:c4:41 inet addr:192.168.1.2 Bcast:192.168.1.255 Mask:255.255.255.0 inet6 addr: fe80::240:f4ff:feba:c441/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:365 errors:0 dropped:0 overruns:0 frame:0 TX packets:377 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:57190 (55.8 KiB) TX bytes:85824 (83.8 KiB) Interrupt:16 Base address:0xe800 eth3 Link encap:Ethernet HWaddr 00:60:67:72:40:42 inet addr:192.168.1.1 Bcast:192.168.1.255 Mask:255.255.255.0 inet6 addr: fe80::260:67ff:fe72:4042/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:2287 errors:0 dropped:0 overruns:0 frame:0 TX packets:1971 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:1414715 (1.3 MiB) TX bytes:425185 (415.2 KiB) Interrupt:17 Base address:0xe400 lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:16436 Metric:1 RX packets:150 errors:0 dropped:0 overruns:0 frame:0 TX packets:150 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:15596 (15.2 KiB) TX bytes:15596 (15.2 KiB) ppp0 Link encap:Point-to-Point Protocol inet addr:150.101.177.X P-t-P:150.101.180.24 Mask:255.255.255.255 UP POINTOPOINT RUNNING NOARP MULTICAST MTU:1492 Metric:1 RX packets:1955 errors:0 dropped:0 overruns:0 frame:0 TX packets:1446 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:3 RX bytes:1344970 (1.2 MiB) TX bytes:353725 (345.4 KiB) ppp1 Link encap:Point-to-Point Protocol inet addr:150.101.179.X P-t-P:150.101.180.143 Mask:255.255.255.255 UP POINTOPOINT RUNNING NOARP MULTICAST MTU:1492 Metric:1 RX packets:28 errors:0 dropped:0 overruns:0 frame:0 TX packets:37 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:3 RX bytes:6691 (6.5 KiB) TX bytes:10285 (10.0 KiB)我可以撥打兩個連接，它們都成功應答和驗證。
gateway:~# cat /etc/network/interfaces # This file describes the network interfaces available on your system # and how to activate them. For more information, see interfaces(5). # The loopback network interface auto lo iface lo inet loopback # The primary network interface allow-hotplug eth1 iface eth1 inet static address 192.168.5.254 netmask 255.255.255.0 broadcast 192.168.5.255 auto eth3 allow-hotplug eth3 iface eth3 inet dhcp auto eth2 allow-hotplug eth2 iface eth2 inet dhcp auto dsl-provider1 iface dsl-provider1 inet ppp pre-up /sbin/ifconfig eth3 up # line maintained by pppoeconf #post-up ip route add 150.101.180.143 dev eth1 src 150.101.179.X table T2 #post-up ip route add default via 150.101.180.143 table T2 #post-up ip rule add from 150.101.179.X table T2 #post-down ip rule del from 150.101.179.X table T2 provider dsl-provider1 auto dsl-provider iface dsl-provider inet ppp pre-up /sbin/ifconfig eth2 up # line maintained by pppoeconf #post-up ip route add 150.101.180.24 dev eth2 src 150.101.177.X table T1 #post-up ip route add default via 150.101.180.24 table T1 #post-up ip rule add from 150.101.177.X table T1 #post-down ip rule del from 150.101.177.X table T1 provider dsl-provider gateway:~#正如你在上面看到的，我已經註釋掉了post-up和down的設置ip路由我應該在ip route命令中使用ethX作為dev嗎？還是應該是 pppX？我還注意到，當任何介面更改時，ip 路由都會刷新並且更改會失去。這是我的 rt_tables 文件。
gateway:~# cat /etc/iproute2/rt_tables # # reserved values # 255 local 254 main 253 default 0 unspec # # local # #1 inr.ruhep 200 uplink1 201 uplink2 100 T1 101 T2 gateway:~#這是我的 ip 表腳本。我知道它需要更改（尤其是預設規則），但除此之外： - 它在一個連接啟動後工作，並且
#!/bin/sh INTIF="eth1" EXTIF="ppp0" EXTIF2="ppp1" EXTIP="`/sbin/ifconfig ppp0 | grep 'inet addr' | awk '{print $2}' | sed -e 's/.*://'`" EXTIP2="`/sbin/ifconfig ppp1 | grep 'inet addr' | awk '{print $2}' | sed -e 's/.*://'`" /sbin/depmod -a /sbin/modprobe ip_tables /sbin/modprobe ip_conntrack /sbin/modprobe ip_conntrack_ftp /sbin/modprobe ip_conntrack_irc /sbin/modprobe iptable_nat /sbin/modprobe ip_nat_ftp echo "1" > /proc/sys/net/ipv4/ip_forward echo "1" > /proc/sys/net/ipv4/ip_dynaddr iptables -P INPUT ACCEPT iptables -F INPUT iptables -P OUTPUT ACCEPT iptables -F OUTPUT iptables -P FORWARD DROP iptables -F FORWARD iptables -t nat -F iptables -A FORWARD -i $EXTIF -o $INTIF -m state --state ESTABLISHED,RELATED -j ACCEPT iptables -A FORWARD -i $INTIF -o $EXTIF -j ACCEPT iptables -t nat -A POSTROUTING -o $EXTIF -j MASQUERADE iptables -A FORWARD -i $EXTIF2 -o $INTIF -m state --state ESTABLISHED,RELATED -j ACCEPT iptables -A FORWARD -i $INTIF -o $EXTIF2 -j ACCEPT iptables -t nat -A POSTROUTING -o $EXTIF2 -j MASQUERADE #Transparent Proxy iptables -t nat -A PREROUTING -i $INTIF -p tcp --dport 80 -j REDIRECT --to-port 3128 #Mail iptables -A FORWARD -i $EXTIF -o $INTIF -d 192.168.5.4 -p tcp --dport 25 -j ACCEPT iptables -t nat -A PREROUTING -i $EXTIF -d $EXTIP -p tcp --dport 25 -j DNAT --to 192.168.5.4 iptables -A FORWARD -i $EXTIF2 -o $INTIF -d 192.168.5.4 -p tcp --dport 25 -j ACCEPT iptables -t nat -A PREROUTING -i $EXTIF2 -d $EXTIP2 -p tcp --dport 25 -j DNAT --to 192.168.5.4 #HTTPS (webmail) iptables -A FORWARD -i $EXTIF -o $INTIF -d 192.168.5.4 -p tcp --dport 443 -j ACCEPT iptables -t nat -A PREROUTING -i $EXTIF -d $EXTIP -p tcp --dport 443 -j DNAT --to 192.168.5.4 iptables -A FORWARD -i $EXTIF2 -o $INTIF -d 192.168.5.4 -p tcp --dport 443 -j ACCEPT iptables -t nat -A PREROUTING -i $EXTIF2 -d $EXTIP2 -p tcp --dport 443 -j DNAT --to 192.168.5.4 #IMAPS iptables -A FORWARD -i $EXTIF -o $INTIF -d 192.168.5.4 -p tcp --dport 993 -j ACCEPT iptables -t nat -A PREROUTING -i $EXTIF -d $EXTIP -p tcp --dport 993 -j DNAT --to 192.168.5.4 iptables -A FORWARD -i $EXTIF2 -o $INTIF -d 192.168.5.4 -p tcp --dport 993 -j ACCEPT iptables -t nat -A PREROUTING -i $EXTIF2 -d $EXTIP2 -p tcp --dport 993 -j DNAT --to 192.168.5.4 #POP3 iptables -A FORWARD -i $EXTIF -o $INTIF -d 192.168.5.4 -p tcp --dport 110 -j ACCEPT iptables -t nat -A PREROUTING -i $EXTIF -d $EXTIP -p tcp --dport 110 -j DNAT --to 192.168.5.4 iptables -A FORWARD -i $EXTIF2 -o $INTIF -d 192.168.5.4 -p tcp --dport 110 -j ACCEPT iptables -t nat -A PREROUTING -i $EXTIF2 -d $EXTIP2 -p tcp --dport 110 -j DNAT --to 192.168.5.4 #VPN iptables -A FORWARD -i $EXTIF -o $INTIF -d 192.168.5.4 -p tcp --dport 1723 -j ACCEPT iptables -t nat -A PREROUTING -i $EXTIF -d $EXTIP -p tcp --dport 1723 -j DNAT --to 192.168.5.4 iptables -A FORWARD -i $EXTIF2 -o $INTIF -d 192.168.5.4 -p tcp --dport 1723 -j ACCEPT iptables -t nat -A PREROUTING -i $EXTIF2 -d $EXTIP2 -p tcp --dport 1723 -j DNAT --to 192.168.5.4 #HTTP iptables -A FORWARD -i $EXTIF -o $INTIF -d 192.168.5.4 -p tcp --dport 80 -j ACCEPT iptables -t nat -A PREROUTING -i $EXTIF -d $EXTIP -p tcp --dport 80 -j DNAT --to 192.168.5.4 iptables -A FORWARD -i $EXTIF2 -o $INTIF -d 192.168.5.4 -p tcp --dport 80 -j ACCEPT iptables -t nat -A PREROUTING -i $EXTIF2 -d $EXTIP2 -p tcp --dport 80 -j DNAT --to 192.168.5.4 #Bridgit iptables -A FORWARD -i $EXTIF -o $INTIF -d 192.168.5.4 -p tcp --dport 8080 -j ACCEPT iptables -t nat -A PREROUTING -i $EXTIF -d $EXTIP -p tcp --dport 8080 -j DNAT --to 192.168.5.4 iptables -A FORWARD -i $EXTIF2 -o $INTIF -d 192.168.5.4 -p tcp --dport 8080 -j ACCEPT iptables -t nat -A PREROUTING -i $EXTIF2 -d $EXTIP2 -p tcp --dport 8080 -j DNAT --to 192.168.5.4 #GATEWAY2="150.101.180.143" #GATEWAY="150.101.180.24" #ip route add $GATEWAY dev $EXTIF src $EXTIP table T1 #ip route add default via $GATEWAY table T1 #ip route add $GATEWAY2 dev $EXTIF2 src $EXTIP2 table T2 #ip route add default via $GATEWAY2 table T2 #ip rule add from $EXTIP table T1 #ip rule add from $EXTIP2 table T2 #ip route add default scope global nexthop via $GATEWAY dev $EXTIF weight 1 nexthop via $GATEWAY2 dev $EXTIF2 weight 1任何想法都會很棒。
謝謝，
麥克風
編輯：這是從這個問題的評論中請求的請求的命令和輸出。謝謝！
說明：我已經打開了機器，兩個界面在啟動時自動出現（ppp 自動撥號和連接）。只要我關閉一個界面，您就可以看到它可以工作。
login as: root root@192.168.5.254's password: Linux gateway 2.6.26-2-686 #1 SMP Thu Sep 16 19:35:51 UTC 2010 i686 The programs included with the Debian GNU/Linux system are free software; the exact distribution terms for each program are described in the individual files in /usr/share/doc/*/copyright. Debian GNU/Linux comes with ABSOLUTELY NO WARRANTY, to the extent permitted by applicable law. Last login: Wed Nov 3 04:07:28 2010 from 192.168.5.38 gateway:~# ping google.com ping: unknown host google.com gateway:~# ip route 150.101.180.24 dev ppp0 proto kernel scope link src 150.101.179.XXX 150.101.180.24 dev ppp1 proto kernel scope link src 150.101.177.XXX 192.168.5.0/24 dev eth1 proto kernel scope link src 192.168.5.254 192.168.1.0/24 dev eth2 proto kernel scope link src 192.168.1.2 192.168.1.0/24 dev eth3 proto kernel scope link src 192.168.1.3 default via 192.168.1.254 dev eth3 default via 192.168.1.254 dev eth2 default dev ppp1 scope link default dev ppp0 scope link gateway:~# ip link show 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWN link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 2: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 10 00 link/ether 00:24:8c:4e:31:e7 brd ff:ff:ff:ff:ff:ff 3: eth2: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UNKNOWN ql en 1000 link/ether 00:40:f4:ba:c4:41 brd ff:ff:ff:ff:ff:ff 4: eth3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UNKNOWN ql en 1000 link/ether 00:60:67:72:40:42 brd ff:ff:ff:ff:ff:ff 5: ppp0: <POINTOPOINT,MULTICAST,NOARP,UP,LOWER_UP> mtu 1492 qdisc pfifo_fast state UN KNOWN qlen 3 link/ppp 6: ppp1: <POINTOPOINT,MULTICAST,NOARP,UP,LOWER_UP> mtu 1492 qdisc pfifo_fast state UN KNOWN qlen 3 link/ppp gateway:~# clear gateway:~# ip link show 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWN link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 2: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000 link/ether 00:24:8c:4e:31:e7 brd ff:ff:ff:ff:ff:ff 3: eth2: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UNKNOWN qlen 1000 link/ether 00:40:f4:ba:c4:41 brd ff:ff:ff:ff:ff:ff 4: eth3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UNKNOWN qlen 1000 link/ether 00:60:67:72:40:42 brd ff:ff:ff:ff:ff:ff 5: ppp0: <POINTOPOINT,MULTICAST,NOARP,UP,LOWER_UP> mtu 1492 qdisc pfifo_fast state UNKNOWN qlen 3 link/ppp 6: ppp1: <POINTOPOINT,MULTICAST,NOARP,UP,LOWER_UP> mtu 1492 qdisc pfifo_fast state UNKNOWN qlen 3 link/ppp gateway:~# ip neigh show 192.168.5.38 dev eth1 lladdr 00:1d:60:0a:cb:23 DELAY 192.168.1.254 dev eth3 lladdr 00:04:ed:a9:07:81 REACHABLE 192.168.1.254 dev eth2 lladdr 00:04:ed:aa:cd:45 REACHABLE 192.168.5.43 dev eth1 lladdr 00:08:5d:03:b3:3f STALE 192.168.5.4 dev eth1 lladdr 00:1e:0b:1c:4e:60 STALE gateway:~# ip route get 5.5.5.5 5.5.5.5 via 192.168.1.254 dev eth3 src 192.168.1.3 cache mtu 1500 advmss 1460 hoplimit 64 gateway:~# ping google.com ping: unknown host google.com gateway:~# ping 4.2.2.2 PING 4.2.2.2 (4.2.2.2) 56(84) bytes of data. From 192.168.1.254 icmp_seq=1 Destination Net Unreachable From 192.168.1.254 icmp_seq=2 Destination Net Unreachable ^C --- 4.2.2.2 ping statistics --- 2 packets transmitted, 0 received, +2 errors, 100% packet loss, time 1003ms gateway:~# ifconfig -a eth1 Link encap:Ethernet HWaddr 00:24:8c:4e:31:e7 inet addr:192.168.5.254 Bcast:192.168.5.255 Mask:255.255.255.0 inet6 addr: fe80::224:8cff:fe4e:31e7/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:739 errors:0 dropped:0 overruns:0 frame:0 TX packets:303 errors:0 dropped:0 overruns:0 carrier:2 collisions:0 txqueuelen:1000 RX bytes:59730 (58.3 KiB) TX bytes:35821 (34.9 KiB) Interrupt:219 eth2 Link encap:Ethernet HWaddr 00:40:f4:ba:c4:41 inet addr:192.168.1.2 Bcast:192.168.1.255 Mask:255.255.255.0 inet6 addr: fe80::240:f4ff:feba:c441/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:152 errors:0 dropped:0 overruns:0 frame:0 TX packets:119 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:15328 (14.9 KiB) TX bytes:8207 (8.0 KiB) Interrupt:16 Base address:0xe800 eth3 Link encap:Ethernet HWaddr 00:60:67:72:40:42 inet addr:192.168.1.3 Bcast:192.168.1.255 Mask:255.255.255.0 inet6 addr: fe80::260:67ff:fe72:4042/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:521 errors:0 dropped:0 overruns:0 frame:0 TX packets:758 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:48899 (47.7 KiB) TX bytes:57096 (55.7 KiB) Interrupt:17 Base address:0xe400 lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:16436 Metric:1 RX packets:20 errors:0 dropped:0 overruns:0 frame:0 TX packets:20 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:1160 (1.1 KiB) TX bytes:1160 (1.1 KiB) ppp0 Link encap:Point-to-Point Protocol inet addr:150.101.179.XXX P-t-P:150.101.180.24 Mask:255.255.255.255 UP POINTOPOINT RUNNING NOARP MULTICAST MTU:1492 Metric:1 RX packets:61 errors:0 dropped:0 overruns:0 frame:0 TX packets:3 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:3 RX bytes:7454 (7.2 KiB) TX bytes:54 (54.0 B) ppp1 Link encap:Point-to-Point Protocol inet addr:150.101.177.XXX P-t-P:150.101.180.24 Mask:255.255.255.255 UP POINTOPOINT RUNNING NOARP MULTICAST MTU:1492 Metric:1 RX packets:127 errors:0 dropped:0 overruns:0 frame:0 TX packets:3 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:3 RX bytes:6278 (6.1 KiB) TX bytes:54 (54.0 B) gateway:~# ifdown eth2 There is already a pid file /var/run/dhclient.eth2.pid with pid 2217 killed old client process, removed PID file Internet Systems Consortium DHCP Client V3.1.1 Copyright 2004-2008 Internet Systems Consortium. All rights reserved. For info, please visit http://www.isc.org/sw/dhcp/ Listening on LPF/eth2/00:40:f4:ba:c4:41 Sending on LPF/eth2/00:40:f4:ba:c4:41 Sending on Socket/fallback DHCPRELEASE on eth2 to 192.168.1.254 port 67 gateway:~# ping google.com PING google.com (66.102.11.104) 56(84) bytes of data. 64 bytes from syd01s01-in-f104.1e100.net (66.102.11.104): icmp_seq=1 ttl=58 time=32.8 ms 64 bytes from syd01s01-in-f104.1e100.net (66.102.11.104): icmp_seq=2 ttl=58 time=32.7 ms 64 bytes from syd01s01-in-f104.1e100.net (66.102.11.104): icmp_seq=3 ttl=58 time=32.9 ms 64 bytes from syd01s01-in-f104.1e100.net (66.102.11.104): icmp_seq=4 ttl=57 time=33.3 ms 64 bytes from syd01s01-in-f104.1e100.net (66.102.11.104): icmp_seq=5 ttl=57 time=32.6 ms ^C --- google.com ping statistics --- 5 packets transmitted, 5 received, 0% packet loss, time 4017ms rtt min/avg/max/mdev = 32.694/32.923/33.373/0.263 ms gateway:~# ifup eth2 Internet Systems Consortium DHCP Client V3.1.1 Copyright 2004-2008 Internet Systems Consortium. All rights reserved. For info, please visit http://www.isc.org/sw/dhcp/ Listening on LPF/eth2/00:40:f4:ba:c4:41 Sending on LPF/eth2/00:40:f4:ba:c4:41 Sending on Socket/fallback DHCPDISCOVER on eth2 to 255.255.255.255 port 67 interval 8 DHCPOFFER from 192.168.1.254 DHCPREQUEST on eth2 to 255.255.255.255 port 67 DHCPACK from 192.168.1.254 bound to 192.168.1.2 -- renewal in 20576 seconds. if-up.d/mountnfs[eth2]: waiting for interface dsl-provider1 before doing NFS mounts (warning). if-up.d/mountnfs[eth2]: waiting for interface dsl-provider before doing NFS mounts (warning). gateway:~# ping google.com PING google.com (66.102.11.104) 56(84) bytes of data. ^C --- google.com ping statistics --- 5 packets transmitted, 0 received, 100% packet loss, time 4013ms gateway:~# ifdown eth3 There is already a pid file /var/run/dhclient.eth3.pid with pid 2523 killed old client process, removed PID file Internet Systems Consortium DHCP Client V3.1.1 Copyright 2004-2008 Internet Systems Consortium. All rights reserved. For info, please visit http://www.isc.org/sw/dhcp/ Listening on LPF/eth3/00:60:67:72:40:42 Sending on LPF/eth3/00:60:67:72:40:42 Sending on Socket/fallback DHCPRELEASE on eth3 to 192.168.1.254 port 67 gateway:~# ping google.com ping: unknown host google.com gateway:~# ping 4.2.2.2 connect: Network is unreachable gateway:~# ping 4.2.2.2 connect: Network is unreachable gateway:~# ip route 150.101.180.24 dev ppp0 proto kernel scope link src 150.101.179.XXX 192.168.5.0/24 dev eth1 proto kernel scope link src 192.168.5.254 192.168.1.0/24 dev eth2 proto kernel scope link src 192.168.1.2 gateway:~# route Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 150.101.180.24 * 255.255.255.255 UH 0 0 0 ppp0 192.168.5.0 * 255.255.255.0 U 0 0 0 eth1 192.168.1.0 * 255.255.255.0 U 0 0 0 eth2 gateway:~# ping google.com ping: unknown host google.com gateway:~# plog Nov 11 17:17:07 gateway pppd[2139]: sendPacket: send: Network is down Nov 11 17:17:07 gateway pppd[2139]: Exit. gateway:~# poff -a gateway:~# pon dsl-provider Plugin rp-pppoe.so loaded. gateway:~# pon dsl-provider1 Plugin rp-pppoe.so loaded. gateway:~# ping google.com PING google.com (66.102.11.104) 56(84) bytes of data. 64 bytes from syd01s01-in-f104.1e100.net (66.102.11.104): icmp_seq=1 ttl=57 time=32.8 ms 64 bytes from syd01s01-in-f104.1e100.net (66.102.11.104): icmp_seq=2 ttl=58 time=32.5 ms 64 bytes from syd01s01-in-f104.1e100.net (66.102.11.104): icmp_seq=3 ttl=57 time=32.9 ms 64 bytes from syd01s01-in-f104.1e100.net (66.102.11.104): icmp_seq=4 ttl=57 time=32.3 ms ^C --- google.com ping statistics --- 4 packets transmitted, 4 received, 0% packet loss, time 3008ms rtt min/avg/max/mdev = 32.373/32.657/32.906/0.218 ms gateway:~# gateway:~# ip route get 5.5.5.5 5.5.5.5 dev ppp0 src 150.101.179.XXX cache mtu 1492 advmss 1452 hoplimit 64 gateway:~#
正如你在這裡看到的
gateway:~# ip route 150.101.180.24 dev ppp0 proto kernel scope link src 150.101.179.XXX 150.101.180.24 dev ppp1 proto kernel scope link src 150.101.177.XXX 192.168.5.0/24 dev eth1 proto kernel scope link src 192.168.5.254 192.168.1.0/24 dev eth2 proto kernel scope link src 192.168.1.2 192.168.1.0/24 dev eth3 proto kernel scope link src 192.168.1.3 > default via 192.168.1.254 dev eth3 > default via 192.168.1.254 dev eth2 > default dev ppp1 scope link > default dev ppp0 scope link您有 4 條預設路由。當您嘗試訪問非本地主機時，選擇以下 4 個之一：
gateway:~# ip route get 5.5.5.5 5.5.5.5 via 192.168.1.254 dev eth3 src 192.168.1.3 cache mtu 1500 advmss 1460 hoplimit 64在這種情況下 eth3，它不會讓您到達所需的目的地。您要求轉發數據包的網關（192.168.1.254）如實響應，它沒有通往目標網路的路徑：
gateway:~# ping 4.2.2.2 PING 4.2.2.2 (4.2.2.2) 56(84) bytes of data. From 192.168.1.254 icmp_seq=1 Destination Net Unreachable我不知道那些通過 ethX 的預設路由來自哪裡，但你需要擺脫它們：
ip route del default via 192.168.1.254 dev eth3 ip route del default via 192.168.1.254 dev eth2如果您的設置在那之後沒有按預期工作，則輸出
ip rule show可能有助於進一步調試。