Linux Ask!

Linux Ask! is a Q & A web site specific for Linux related questions. Questions are collected, answered and audited by experienced Linux users.

Mar 092013
 

Traceroute using TCP

Answer:

It is common now for a server to disable the ICMP and make commands like *ping* & *traceroute* failed to do the diagnostics. However, newer version of *traceroute* have a TCP mode that if you know a particular server is opening a port for TCP connection, then you can use command like..

# sudo traceroute -T www.google.com
traceroute to www.google.com (74.125.235.242), 30 hops max, 60 byte packets
 1  136.182.34.2 (136.182.34.2)  0.557 ms  0.572 ms  0.621 ms
 2  125.235.129.111 (125.235.129.111)  11.232 ms  11.242 ms  11.235 ms
 3  otejbb205.int-gw.kddi.ne.jp (124.215.194.161)  1.602 ms otejbb206.int-gw.kddi.ne.jp (124.215.194.177)  2.123 ms  2.119 ms
 4  ix-ote210.int-gw.kddi.ne.jp (106.187.6.114)  11.182 ms ix-ote210.int-gw.kddi.ne.jp (106.187.6.98)  11.156 ms ix-ote210.int-gw.kddi.ne.jp (106.187.6.114)  11.199 ms
 5  203.181.102.94 (203.181.102.94)  63.248 ms  63.272 ms  63.262 ms
 6  209.85.249.195 (209.85.249.195)  2.523 ms  2.252 ms  2.191 ms
 7  64.233.175.0 (64.233.175.0)  6.512 ms  6.448 ms  6.537 ms
 8  64.233.174.0 (64.233.174.0)  11.154 ms  11.474 ms  10.738 ms
 9  216.239.43.243 (216.239.43.243)  11.108 ms  11.713 ms  12.141 ms
10  kix01s02-in-f18.1e100.net (74.125.235.242)  11.103 ms  10.582 ms  10.882 ms
Feb 212013
 

Diagnosing network connectivity with mtr

Answer:

To check the network connectivity to a specific server, you can use the mtr command.

e.g.

# mtr --report google.com
HOST: localhost                   Loss%   Snt   Last   Avg  Best  Wrst StDev
  1. 106.187.33.2                  0.0%    10    1.3   5.3   0.6  21.4   6.7
  2. 124.215.199.121               0.0%    10    0.6   6.5   0.4  12.4   4.8
  3. otejbb206.int-gw.kddi.ne.jp   0.0%    10    2.1   3.7   2.1  12.5   3.3
  4. ix-ote210.int-gw.kddi.ne.jp   0.0%    10    2.1   6.4   2.1  15.2   4.5
  5. 203.181.102.94                0.0%    10    2.6   2.7   2.2   3.9   0.6
  6. 209.85.249.195                0.0%    10    3.2   5.3   2.3  22.8   6.6
  7. 64.233.175.0                  0.0%    10    7.0  13.5   6.8  49.8  13.7
  8. 64.233.174.0                  0.0%    10   20.0  12.7  11.1  20.0   3.0
  9. 216.239.43.145                0.0%    10   12.0  11.8  11.5  12.2   0.2
 10. kix01s01-in-f8.1e100.net      0.0%    10   11.2  11.4  11.1  11.9   0.3