traceroute疑问(新手发问)

ghp268

traceroute  -n www.sina.com

1. traceroute to [url]www.sina.com[/url] (121.194.0.210), 30 hops max, 60 byte packets
   
2. 1  222.25.170.126 (222.25.170.126)  3.128 ms  3.719 ms  4.305 ms
   
3. 2  192.168.1.17 (192.168.1.17)  0.318 ms  0.340 ms  0.339 ms
   
4. 3  192.169.255.254 (192.169.255.254)  0.933 ms  1.147 ms  1.168 ms
   
5. 4  210.27.15.33 (210.27.15.33)  0.861 ms  0.945 ms  0.967 ms
   
6. 5  * * *
   
7. 6  202.200.29.141 (202.200.29.141)  1.890 ms  3.225 ms  4.476 ms
   
8. 7  202.200.29.9 (202.200.29.9)  2.304 ms  3.534 ms  4.624 ms
   
9. 8  202.200.29.5 (202.200.29.5)  1.262 ms *  1.534 ms
   
10. 9  202.112.53.141 (202.112.53.141)  17.339 ms  17.353 ms  17.895 ms
    
11. 10  bjxa4.cernet.net (202.112.46.149)  17.866 ms  17.838 ms  17.770 ms
    
12. 11  202.127.216.238 (202.127.216.238)  18.161 ms * *
    
13. 12  sjz1.cernet.net (202.112.38.106)  17.414 ms  17.462 ms  17.489 ms
    
14. 13  121.194.15.245 (121.194.15.245)  18.566 ms  19.016 ms  19.149 ms
    
15. 14  * * *
    
16. 15  * * *
    
17. 16  * * *
    
18. 17  * * *
    
19. 18  * * *
    
20. 19  * * *
    
21. 20  * * *
    
22. 21  * * *
    
23. 22  * * *
    
24. 23  * * *
    
25. 24  * * *
    
26. 25  * * *
    
27. 26  * * *
    
28. 27  * * *
    
29. 28  * * *
    
30. 29  * * *
    
31. 30  * * *

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我去traceroute www.baidu.com 也是追踪不到
但是去追踪 g.cn 能够准确追踪到

1. traceroute to g.cn (203.208.39.104), 30 hops max, 60 byte packets
   
2. 1  222.25.170.126  3.904 ms  4.508 ms  5.131 ms
   
3. 2  192.168.1.17  0.330 ms  0.343 ms  0.371 ms
   
4. 3  192.169.255.254  2.843 ms  3.014 ms  3.108 ms
   
5. 4  210.27.15.33  19.094 ms  19.047 ms  19.001 ms
   
6. 5  192.170.255.254  31.209 ms  31.488 ms  31.795 ms
   
7. 6  172.16.254.254  4.763 ms  4.675 ms  4.647 ms
   
8. 7  61.150.43.65  1.067 ms  0.993 ms  1.177 ms
   
9. 8  222.91.155.5  1.162 ms  1.695 ms  2.359 ms
   
10. 9  61.134.0.53  1.302 ms  1.259 ms  1.785 ms
    
11. 10  202.97.38.177  30.351 ms  30.442 ms  30.396 ms
    
12. 11  202.97.34.193  25.311 ms  25.785 ms  25.742 ms
    
13. 12  202.97.57.190  24.570 ms  24.583 ms  24.618 ms
    
14. 13  202.97.57.190  24.446 ms  24.487 ms  24.446 ms
    
15. 14  203.208.62.118  31.293 ms  37.704 ms  37.633 ms
    
16. 15  203.208.62.118  37.551 ms  37.487 ms  37.342 ms
    
17. 16  203.208.39.104  25.124 ms  25.134 ms  25.259 ms

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请问这是什么原因？

kentchoi

楼主先分析 traceroute 程序的运作方式，应该能够了解的。。。

ghp268

看了MAN上的说明
In the modern network environment the traditional traceroute methods can not be always applicable
because of widespread use of  firewalls.  
Such firewalls  filter  the  "unlikely" UDP ports or even ICMP echoes.
To solve this, some additional tracerouting methods are implemented (including tcp)