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Old 11-25-2009, 09:38 AM   #1
tdewire
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Talking IP/DNS problem? Ubuntu server+desktop = "no valid net connections found"


hi all,
i'm a server newbie. i set up a box with ubuntu DNS/Firewall server per the excellent instructions @ http://linuxgazette.net/141/lazar.html. Great article Shane! The ubuntu 9.1 desktop connected to the server says "no valid network connections found" and the live network icon does not appear on the upper right hand corner. But! when i run ethtool eth0 in the terminal I get "Link detected: yes". I can ping the server and other boxes in my network. I cannot ping the internet. I can ping the internet from the DNS server and another server behind the firewall. thank u!

Last edited by GrapefruiTgirl; 11-26-2009 at 10:46 AM. Reason: improved title
 
Old 11-26-2009, 10:11 AM   #2
catkin
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An ASCII art diagram of the network, showing the IP nodes implementing DNS server, firewall and the Internet gateway with IP their addresses would help along with the output from
Code:
ifconfig
route
traceroute 75.126.162.205
nslookup linuxquestions.org
This is an IP (and maybe DNS) problem, not specific to "Home Server On A Silver Platter" so a change of title might get more response; LQers who are not familiar with "Home Server On A Silver Platter" (most of us) are probably not viewing the thread. You can change the title of your post via the Edit button (and maybe need to lick Advanced after that).

A useful guide to asking effective questions: LQ's How To Ask a Question
 
Old 11-27-2009, 03:34 AM   #3
tdewire
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Thanks Catkin. Here is a diagram of the network:http://imgur.com/AFdwJ.png

The follwing is output from the ubuntu desktop:

ifconfig eth0
eth0 Link encap:Ethernet HWaddr 00:13:72:9d:7e:ba
inet addr:192.168.0.5 Bcast:192.168.0.255 Mask:255.255.255.0
inet6 addr: fe80::213:72ff:fe9d:7eba/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:608 errors:0 dropped:0 overruns:0 frame:0
TX packets:653 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:100
RX bytes:79562 (79.5 KB) TX bytes:66321 (66.3 KB)

route
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
192.168.0.0 * 255.255.255.0 U 0 0 0 eth0
link-local * 255.255.0.0 U 1000 0 0 eth0
default router 0.0.0.0 UG 100 0 0 eth0



traceroute 75.126.162.205
traceroute to 75.126.162.205 (75.126.162.205), 30 hops max, 60 byte packets
1 * * *
2 * * *
3 * * *
4 * * *
5 * 204.186.240.197 (204.186.240.197) 8.093 ms 12.094 ms
6 207.44.127.110 (207.44.127.110) 22.063 ms 16.414 ms 13.539 ms
7 207.44.122.178 (207.44.122.178) 10.629 ms 12.716 ms 8.985 ms
8 207.44.125.6 (207.44.125.6) 17.927 ms 15.796 ms 18.389 ms
9 4.78.132.69 (4.78.132.69) 15.263 ms 16.201 ms 14.912 ms
10 4.68.16.254 (4.68.16.254) 34.183 ms 4.68.16.62 (4.68.16.62) 19.953 ms 4.68.16.190 (4.68.16.190) 20.205 ms
11 4.69.134.113 (4.69.134.113) 14.674 ms 4.69.134.125 (4.69.134.125) 14.453 ms 4.69.134.121 (4.69.134.121) 21.698 ms
12 4.69.137.121 (4.69.137.121) 51.195 ms 50.434 ms 52.185 ms
13 4.69.145.8 (4.69.145.8) 49.363 ms 4.69.145.72 (4.69.145.72) 50.686 ms 4.69.145.8 (4.69.145.8) 49.176 ms
14 4.71.198.18 (4.71.198.18) 49.671 ms 48.683 ms 48.657 ms
15 66.228.118.201 (66.228.118.201) 59.420 ms 60.184 ms 50.676 ms
16 66.228.118.178 (66.228.118.178) 50.171 ms 50.435 ms 50.439 ms
17 75.126.162.205 (75.126.162.205) 57.424 ms 57.436 ms 55.933 ms

nslookup linuxquestions.org
;; connection timed out; no servers could be reached

thank u!

Last edited by tdewire; 11-27-2009 at 05:26 AM.
 
Old 11-30-2009, 09:21 AM   #4
catkin
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Registered: Dec 2008
Location: Tamil Nadu, India
Distribution: Servers: Debian Squeeze and Wheezy. Desktop: Slackware64 14.0. Netbook: Slackware 13.37
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Quote:
Originally Posted by tdewire View Post
Thanks Catkin. Here is a diagram of the network:http://imgur.com/AFdwJ.png
Nice diagram!


Quote:
Originally Posted by tdewire View Post
Code:
route
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
192.168.0.0     *               255.255.255.0   U     0      0        0 eth0
link-local      *               255.255.0.0     U     1000   0        0 eth0
default         router          0.0.0.0         UG    100    0        0 eth0
Weird looking (= "I don't understand it") default route but the subsequent traceroute shows it's working OK.

Quote:
Originally Posted by tdewire View Post
Code:
nslookup linuxquestions.org
;; connection timed out; no servers could be reached
Houston! We have a DNS problem!

What's in your /etc/resolv.conf file? If it is 192.168.0.1 (as suggested by your diagram), is that device providing a good DNS service (Does it work for the other machine? Does it pass its own DNS diagnostics). You could try by-passing 192.168.0.1 and test using some public DNS servers such as:

Level 3
4.2.2.1
4.2.2.2
4.2.2.3
4.2.2.4

OpenDNS
208.67.222.222
208.67.220.220

Only the first 3 DNS servers listed in resolv.conf are normally used.
 
  


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