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VPN 与本地网共存

Posted by: tigerz on Jan. 24, 2010

route vpn 路由

本地网和 VPN 怎么共存

由于很多原因, 经常会使用 VPN. VPN 有很多优点, 比如安全, 比如可以避开一些不必要的麻烦. 不过 VPN 也带来一些新麻烦, 例如, 访问一些本地服务器速度往往会慢很多.

如何才能让部分数据包走 VPN, 部分走本地网呢?

路由表

经过分析, 发现一般 VPN 客户端在 VPN 连接建立后, 会修改路由表添加一个默认路由, 让所有的数据包都走 VPN. 如果对路由表进行相应调整, 应该可以达到目的.

实例

连接 VPN 前的路由表 

$ route print
...
Active Routes:
Network Destination        Netmask          Gateway       Interface  Metric
        0.0.0.0          0.0.0.0      192.168.1.1     192.168.1.4     1
        127.0.0.0        255.0.0.0        127.0.0.1       127.0.0.1   1
    169.254.0.0      255.255.0.0    192.168.235.1   192.168.235.1     30
    192.168.1.0    255.255.255.0      192.168.1.4     192.168.1.4     20
    192.168.1.4  255.255.255.255        127.0.0.1       127.0.0.1     20
    192.168.1.255  255.255.255.255      192.168.1.4     192.168.1.4   20
    192.168.20.0    255.255.255.0     192.168.20.1    192.168.20.1    20
    192.168.20.1  255.255.255.255        127.0.0.1       127.0.0.1    20
192.168.20.255  255.255.255.255     192.168.20.1    192.168.20.1      20
    192.168.235.0    255.255.255.0    192.168.235.1   192.168.235.1   20
    192.168.235.1  255.255.255.255        127.0.0.1       127.0.0.1   20
192.168.235.255  255.255.255.255    192.168.235.1   192.168.235.1     20
        224.0.0.0        240.0.0.0      192.168.1.4     192.168.1.4   20
        224.0.0.0        240.0.0.0     192.168.20.1    192.168.20.1   20
        224.0.0.0        240.0.0.0    192.168.235.1   192.168.235.1   20
255.255.255.255  255.255.255.255      192.168.1.4     192.168.1.4     1
255.255.255.255  255.255.255.255     192.168.20.1    192.168.20.1     1
255.255.255.255  255.255.255.255    192.168.235.1               6     1
255.255.255.255  255.255.255.255    192.168.235.1               4     1
255.255.255.255  255.255.255.255    192.168.235.1   192.168.235.1     1
255.255.255.255  255.255.255.255    192.168.235.1               8     1
255.255.255.255  255.255.255.255    192.168.235.1               7     1
Default Gateway:       192.168.1.1
===========================================================================
Persistent Routes:
None

到 yun09.com 的路径 

$ tracert yun09.com

Tracing route to yun09.com [220.198.249.163]
over a maximum of 30 hops:

1    <1 ms    <1 ms    <1 ms  192.168.1.1 
2    48 ms    49 ms    48 ms  xxx.30.144.1 
3    43 ms    44 ms    44 ms  xxx.15.150.125 
4    71 ms    44 ms    43 ms  xxx.133.30.230 
5    47 ms    46 ms    46 ms  xxx.145.47.90 
6    47 ms    47 ms    48 ms  xxx.97.60.210 
7     *        *        *     Request timed out.
8    79 ms    79 ms    78 ms  xxx.158.5.205 
9   121 ms   121 ms   121 ms  xxx.158.4.82 
10   130 ms   132 ms   131 ms  xxx.158.14.238 
11   130 ms   130 ms   130 ms  xxx.80.0.66 
12   127 ms   126 ms   126 ms  xxx.80.2.86 
13   136 ms   138 ms   132 ms  xxx.4.224.14 
14   136 ms   136 ms   137 ms  xxx.4.224.174 
15   125 ms   125 ms   125 ms  xxx.198.249.163 

Trace complete.

连接 VPN 后的路由表 

$ route print
...
Active Routes:
Network Destination        Netmask          Gateway       Interface  Metric
        0.0.0.0          0.0.0.0         10.0.0.1     10.4.52.206     1
        0.0.0.0          0.0.0.0      192.168.1.1     192.168.1.4     1
        10.0.0.0        255.0.0.0      10.4.52.206     10.4.52.206    1
    10.4.52.206  255.255.255.255        127.0.0.1       127.0.0.1     1
10.255.255.255  255.255.255.255      10.4.52.206     10.4.52.206      1
        127.0.0.0        255.0.0.0        127.0.0.1       127.0.0.1   1
    130.158.6.85  255.255.255.255      192.168.1.1     192.168.1.4    1
    169.254.0.0      255.255.0.0    192.168.235.1   192.168.235.1     30
    192.168.1.0    255.255.255.0      192.168.1.4     192.168.1.4     20
    192.168.1.4  255.255.255.255        127.0.0.1       127.0.0.1     20
    192.168.1.255  255.255.255.255      192.168.1.4     192.168.1.4   20
    192.168.20.0    255.255.255.0     192.168.20.1    192.168.20.1    20
    192.168.20.1  255.255.255.255        127.0.0.1       127.0.0.1    20
192.168.20.255  255.255.255.255     192.168.20.1    192.168.20.1      20
    192.168.235.0    255.255.255.0    192.168.235.1   192.168.235.1   20
    192.168.235.1  255.255.255.255        127.0.0.1       127.0.0.1   20
192.168.235.255  255.255.255.255    192.168.235.1   192.168.235.1     20
        224.0.0.0        240.0.0.0      10.4.52.206     10.4.52.206   1
        224.0.0.0        240.0.0.0      192.168.1.4     192.168.1.4   20
        224.0.0.0        240.0.0.0     192.168.20.1    192.168.20.1   20
        224.0.0.0        240.0.0.0    192.168.235.1   192.168.235.1   20
255.255.255.255  255.255.255.255      10.4.52.206     10.4.52.206     1
255.255.255.255  255.255.255.255      10.4.52.206               7     1
255.255.255.255  255.255.255.255      10.4.52.206               8     1
255.255.255.255  255.255.255.255      10.4.52.206               4     1
255.255.255.255  255.255.255.255      192.168.1.4     192.168.1.4     1
255.255.255.255  255.255.255.255     192.168.20.1    192.168.20.1     1
255.255.255.255  255.255.255.255    192.168.235.1   192.168.235.1     1
Default Gateway:          10.0.0.1
===========================================================================
Persistent Routes:
None

到 yun09.com 的路径 

$ tracert yun09.com

Tracing route to yun09.com [220.198.249.163]
over a maximum of 30 hops:

1   339 ms   339 ms   337 ms  10.0.0.1 
2   341 ms   337 ms   337 ms  univ-tsukuba-accc-axxx-gw.softether.co.jp [xxx.117.219.209] 
3   348 ms   358 ms   352 ms  est1bfxxx.vectant.ne.jp [xxx.139.126.26] 
4   345 ms   355 ms   347 ms  xxx-139-126-30.rv.vectant.ne.jp [xxx.139.126.30] 
5   352 ms   351 ms   351 ms  xxx-139-126-5.rv.vectant.ne.jp [xxx.139.126.5] 
6   348 ms   348 ms   354 ms  ae0.peer1.nihonbashi.vectant.ne.jp [xxx.139.128.226] 
7   362 ms   360 ms   360 ms  tky001bb10.iij.net [58.138.100.37] 
8   358 ms   354 ms   358 ms  tky008bf00.iij.net [58.138.80.9] 
9   354 ms   349 ms   351 ms  tky008bb01.iij.net [58.138.80.250] 
10   349 ms   354 ms   351 ms  tky010ix03.iij.net [58.138.105.182] 
11   800 ms     *        *     210.130.133.70 
12   803 ms   851 ms     *     219.158.29.41 
13   860 ms   862 ms   828 ms  xxx.158.5.113 
14     *      845 ms   867 ms  xxx.158.12.17 
15   877 ms   852 ms   874 ms  xxx.158.10.214 
16   864 ms   887 ms   878 ms  xxx.80.0.66 
17  1033 ms   873 ms   892 ms  xxx.80.2.86 
18   868 ms   858 ms   896 ms  xxx.81.184.2 
19   866 ms   871 ms   859 ms  xxx.4.224.174 
20   867 ms   851 ms   852 ms  xxx.198.249.163 

Trace complete.

修改路由表 

$ route add 220.198.249.163 mask 255.255.255.255 192.168.1.1 metric 5

$ route change 0.0.0.0 mask 0.0.0.0 10.0.0.1 metric 10

$ route print
...
Active Routes:
Network Destination        Netmask          Gateway       Interface  Metric
        0.0.0.0          0.0.0.0         10.0.0.1     10.4.52.206     10
        10.0.0.0        255.0.0.0      10.4.52.206     10.4.52.206    1
    10.4.52.206  255.255.255.255        127.0.0.1       127.0.0.1     1
10.255.255.255  255.255.255.255      10.4.52.206     10.4.52.206      1
        127.0.0.0        255.0.0.0        127.0.0.1       127.0.0.1   1
    130.158.6.85  255.255.255.255      192.168.1.1     192.168.1.4    1
    169.254.0.0      255.255.0.0    192.168.235.1   192.168.235.1     30
    192.168.1.0    255.255.255.0      192.168.1.4     192.168.1.4     20
    192.168.1.4  255.255.255.255        127.0.0.1       127.0.0.1     20
    192.168.1.255  255.255.255.255      192.168.1.4     192.168.1.4   20
    192.168.20.0    255.255.255.0     192.168.20.1    192.168.20.1    20
    192.168.20.1  255.255.255.255        127.0.0.1       127.0.0.1    20
192.168.20.255  255.255.255.255     192.168.20.1    192.168.20.1      20
    192.168.235.0    255.255.255.0    192.168.235.1   192.168.235.1   20
    192.168.235.1  255.255.255.255        127.0.0.1       127.0.0.1   20
192.168.235.255  255.255.255.255    192.168.235.1   192.168.235.1     20
220.198.249.163  255.255.255.255      192.168.1.1     192.168.1.4     5
        224.0.0.0        240.0.0.0      10.4.52.206     10.4.52.206   1
        224.0.0.0        240.0.0.0      192.168.1.4     192.168.1.4   20
        224.0.0.0        240.0.0.0     192.168.20.1    192.168.20.1   20
        224.0.0.0        240.0.0.0    192.168.235.1   192.168.235.1   20
255.255.255.255  255.255.255.255      10.4.52.206     10.4.52.206     1
255.255.255.255  255.255.255.255      10.4.52.206               7     1
255.255.255.255  255.255.255.255      10.4.52.206               8     1
255.255.255.255  255.255.255.255      10.4.52.206               4     1
255.255.255.255  255.255.255.255      192.168.1.4     192.168.1.4     1
255.255.255.255  255.255.255.255     192.168.20.1    192.168.20.1     1
255.255.255.255  255.255.255.255    192.168.235.1   192.168.235.1     1
Default Gateway:          10.0.0.1
===========================================================================
Persistent Routes:
None

到 yun09.com 的路径 

$ tracert yun09.com

Tracing route to yun09.com [220.198.249.163]
over a maximum of 30 hops:

1    <1 ms    <1 ms    <1 ms  192.168.1.1 
2    48 ms    49 ms    48 ms  xxx.30.144.1 
3    43 ms    44 ms    44 ms  xxx.15.150.125 
4    71 ms    44 ms    43 ms  xxx.133.30.230 
5    47 ms    46 ms    46 ms  xxx.145.47.90 
6    47 ms    47 ms    48 ms  xxx.97.60.210 
7     *        *        *     Request timed out.
8    79 ms    79 ms    78 ms  xxx.158.5.205 
9   121 ms   121 ms   121 ms  xxx.158.4.82 
10   130 ms   132 ms   131 ms  xxx.158.14.238 
11   130 ms   130 ms   130 ms  xxx.80.0.66 
12   127 ms   126 ms   126 ms  xxx.80.2.86 
13   136 ms   138 ms   132 ms  xxx.4.224.14 
14   136 ms   136 ms   137 ms  xxx.4.224.174 
15   125 ms   125 ms   125 ms  xxx.198.249.163

可以看到, 现在到 yun09.com 的路径与连接 VPN 之前一样.

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