[NTLUG:Discuss] how to know my gateway?

kbrannen@gte.net kbrannen at gte.net
Mon May 5 21:20:15 CDT 2003


m m wrote:
>> From: kbrannen at gte.net
>> m m wrote:
>>
>>>
>>> Hi, All:
>>>
>>> Recently I reset the at&t cable modem, and the ip changed. the new ip 
>>> is 12.237.83.68 (got it by set dhcp on netconf, and reboot the box)
>>> what is the gw ip for this 12.237.83.68? where do /what tools can 
>>> help me to find out real gw ip?
>>>
>>> I ran route, it show default gw is 12.237.80.1 I wonder this is right 
>>> gw ip for my ip?
>>
>>
>> One of the magic parts of DHCP is that not only does it give/set your 
>> IP, it also communicates your GW (and netmask and all that stuff).  So 
>> that .80.1 IP should be your real GW.  Can you hit a site outside of 
>> AT&T?  If yes, then it is set up correctly. :-)
> 
> 
> yes.
> but no one can hit me, that is why I have the question.
> and this problem bother me a lot, every time when ip changes, I have to 
> fight for the 'right' gw ip in order some one can hit _me_!
> 
> is it possible that the I need to change DNS server ip for that renge of 
> ip address?

Yeh, it sounds like your dynamic DNS service isn't changing in a timely 
manner.  The GW setting on you machine shouldn't matter in people finding you, 
at least as I understand it all.  It obviously matters in you getting to them. :-)

I don't know what name to check, but I can see your machine by IP.

traceroute to 12.237.83.68 (12.237.83.68), 30 hops max, 40 byte packets
  1  gw (192.168.1.1)  2 ms  1 ms  0 ms
  2  tower (172.16.0.1)  315 ms  443 ms  340 ms
  3  frsc-dsldyna-66-228-131-1.advantexcom.net (66.228.131.1)  311 ms  280 ms 
  76 ms
  4  frsc-dsldyna-66-228-142-177.advantexcom.net (66.228.142.177)  136 ms  197 
ms  149 ms
  5  fe0-1-fris.masterlink.net (66.228.128.53)  164 ms  230 ms  105 ms
  6  atm8-0-laco.masterlink.net (66.228.128.18)  45 ms  63 ms *
  7  dal-edge-07.inet.qwest.net (63.149.161.61)  522 ms  438 ms  188 ms
  8  205.171.25.53 (205.171.25.53)  254 ms  252 ms  193 ms
  9  dal-brdr-02.inet.qwest.net (205.171.25.46)  153 ms  185 ms  188 ms
10  205.171.1.14 (205.171.1.14)  346 ms  262 ms  295 ms
11  tbr1-p013802.dlstx.ip.att.net (12.122.12.73)  449 ms  600 ms  282 ms
12  gbr6-p20.dlstx.ip.att.net (12.122.12.70)  212 ms *  140 ms
13  gar3-p370.dlstx.ip.att.net (12.123.17.53)  193 ms  578 ms  355 ms
14  12.244.73.14 (12.244.73.14)  200 ms  310 ms  224 ms
15  * 12.244.113.42 (12.244.113.42)  32 ms  80 ms
16  12-237-83-68.client.attbi.com (12.237.83.68)  79 ms  363 ms  212 ms

OTOH, trying to get to http://12.237.83.68 fails; probably because att.net is 
blocking port 80 along the way, or so I'd guess.  Or at least I'm guessing 
that's why you want people to get to you. ;-)

Maybe this will help you...

[3 ~ /home/kevin] dig 12.237.83.68

; <<>> DiG 9.1.3 <<>> 12.237.83.68
;; global options:  printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 64210
;; flags: qr aa; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 0

;; QUESTION SECTION:
;12.237.83.68.                  IN      A

;; AUTHORITY SECTION:
.                       86400   IN      SOA     a.root-servers.net. 
nstld.verisign-grs.com. 2003050501 1800 900 604800 86400

;; Query time: 299 msec
;; SERVER: 209.176.33.72#53(209.176.33.72)
;; WHEN: Mon May  5 21:17:38 2003
;; MSG SIZE  rcvd: 105


HTH,
Kevin




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