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stevecrye's Avatar
Posts: 226 | Thanked: 38 times | Joined on May 2008 @ Texas/Earth/Sol System/Milky Way/Local Group/Hubble Bubble/Infinity
#1
Hi All;

Having a problem resolving names. My n810 has been setup for dual-boot with Penguinbait's install-tools, so I have the ability to boot to the external SD card or internal flash. The problem only happens when booted to external SD. I just noticed it this morning. A few days ago I had installed a few routine app-manager-delivered updates to things such as wifi-info, nothing major. I forgot to charge it for a few days and it ran out of juice so last night I left it charging.

Name resolution seems to be the only thing that is broken, and it is broken regardless of the app that is trying to do the resolution. If I run nslookup and specify a name host and nameserver, I get a good result. I can ping and traceroute OK if I know the destination IP, and I can browse to sites if I know the IP -for example, my Linksys router's html config screens.

I'd like to try some basic troubleshooting before I re-clone the working flash partition to the external SD card. However, I'm not certain where to start.

ifconfig does not seem to list the DNS, (even when run while booted to the working flash partition). I'm not certain how to do the equivalent of the Windoze ipconfig /all. Does anyone know the correct utility to run to confirm that the NIT has been given a valid IP of a nameserver? Also, what process/daemon is responsible for name resolution? Named?

Tried searching the forums for "can't resolve names" and similar but no luck.

Any and all hand-holding much appreciated!

Thanks,

$teve
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fattomm's Avatar
Posts: 109 | Thanked: 37 times | Joined on Oct 2008 @ NYC, NY
#2
Originally Posted by stevecrye View Post
Hi All;

Name resolution seems to be the only thing that is broken, and it is broken regardless of the app that is trying to do the resolution. If I run nslookup and specify a name host and nameserver, I get a good result. I can ping and traceroute OK if I know the destination IP, and I can browse to sites if I know the IP -for example, my Linksys router's html config screens.

[...]
ifconfig does not seem to list the DNS, (even when run while booted to the working flash partition). I'm not certain how to do the equivalent of the Windoze ipconfig /all. Does anyone know the correct utility to run to confirm that the NIT has been given a valid IP of a nameserver? Also, what process/daemon is responsible for name resolution? Named?

Tried searching the forums for "can't resolve names" and similar but no luck.

Any and all hand-holding much appreciated!

Thanks,

$teve
I think I had something like this some time ago. nslookup, by the way, doesn't use the system resolver configuration.

The NIT uses "dnsmasq", which I don't like much, but is reasonable given the approaches the system takes. Check your /etc/resolv.conf file, and it should have (at least)

nameserver 127.0.0.1

in it. I've added my local domain name, which made life a lot easier. The system resolver libraries read this file, and send DNS requests to the 127.0.0.1 (localhost) server - which is dnsmasq. dnsmasq is ultimately configured to read the file /tmp/resolv.conf.<interface name> -- you should see a /tmp/resolve.conf.wlan0 when your wireless is running.

If your DHCP served up by your wireless router isn't passing over good information (as configured from there, or from whatever DHCP server you're using), then you'll see the shortcomings in this file.

I manually put a "search <myowndomain>" in my /etc/resolve.conf file, since the /tmp/resolve.conf.wlan0 is going to have information from whatever access point I'm tethered to. The "search" in the local file allows me to use short-hand names for my own home systems even when I'm using public access points, friends', or whatever ... (or bluetooth links to my phone).

In short; for default types of parameters you want regardless of your connectivity model, look at /etc/resolv.conf. For specifics passed in via various connection means, look at /tmp/resolve.conf.<interface name>.

I think that should clear things up a bit for you. Broken DNS can be a PITA ...
 

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#3
Try

1.) OpenDNS imported to your /etc/resolv.conf
2.) Use TOR as the DNS server on your tablet
 
brendan's Avatar
Posts: 531 | Thanked: 79 times | Joined on Oct 2006 @ This side of insane, that side of genius
#4
Originally Posted by johndoe32102002 View Post
2.) Use TOR as the DNS server on your tablet
isnt TOR only TCP?

Code:
sudo netstat -nap |grep -i tor
most of DNS is UDP (any satisfied response less that 1500 bytes in size, header included, otherwise TCP) , and the slow TOR network would be totally against why DNS uses UDP - speed.

I2P is what you want to look at for UDP anonymity.
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fattomm's Avatar
Posts: 109 | Thanked: 37 times | Joined on Oct 2008 @ NYC, NY
#5
OpenDNS is possible, TOR is a bit ... mmm, not sure. TOR wouldn't really be applicable. Unless there is some overwhelming reason (for example; a near-paranoid sense of privacy), a provided DNS server is likely to give better service, instead of reaching further into the network (e.g. OpenDNS), invoking latency and increasing the possibility of packet loss.

Most providers provide DNS servers near the edge, to increase the perceived response time of the network, and to cache what will probably be multiple redundant requests.

What appears to be the case in the OP's message is that the DNS server isn't being offered up properly (probably missing a reasonable searched domain, in my opinion). My own catch-all (installed in the /etc/resolve.conf) is to use my own home domain by default, but to follow the DHCP offered DNS server (which is likely to give the best service).
 

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Posts: 739 | Thanked: 159 times | Joined on Sep 2007 @ Germany - Munich
#6
Maybe this ?
 
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