Networking / Browser / DNS problem

[Suppi]

Dear all,

after spending this morning to fix this problem, I run out of ideas.
After booting from Knoppix DVD ( wo options ), I would like to download / install f-prot to scan my local NTFS drives.
However, downloading fails miserably. Access to f-prot.com times out, as it does for heise.de and google.de/google.com .
However, browsing of some(!) websites works.
Pure traceroute of heise.de fails, however traceroute -In of heise.de works.
I can ping, dig and dlint all servers.
As traceroute cannot resolve the names of the servers between me and heise.de, I assume it's a DNS problem.
I have a small home network. My PC is attached to a Switch attached to a router attached to a DSL Router. Both router are setup ( and recognised during dig ) as DNS Proxies.

Any help is greatly appreciated!
Suppi

[tannenba]

My desktop has a VIA Rhine II Fast Ethernet Adapter in it. Knoppix loads ok and dhcp gets the correct ip address. Resolv.conf has the right search domain an ip address, but all apps including pinging my gateway say network is unreachable? I've run out of ideas. It's been more than two years since I have tracked down networking issues in Linux. What am I forgetting?

[tannenba]

Well, saw another post about configuring the net card manually instead of dhcp and
it is working????? All looks the same except I chose a different ip address. Now it
works? The hosts, resolv.conf and hostname files all look the same?

No clue why it is now working.

[Harry Kuhman]

No clue why it is now working.
I don't know if this is the case for you or not, and this is not the same problem as the original poster, but I did have one Belkin router that didn't DHCP handshake quite right. It would work with Windows (likely all that they tested it with), but it would fail with Knoppix or other Linux distros. Like you, I had to manually set up my network configuration (which lasted only until I got fed up with the router and replaced it).

The original poster may be having some issues with his local systems trying to be DNS servers. I would suggest manually setting the DNS server to a real DNS server on the Internet, bypassing the local router, and seeing if that doesn't change something.

I would also look into the availability of firmware updates for both your router and the router of the original poster.

[tannenba]

Thanks for your answer. My router however, works fine with my debian LAMP server and my old 486 Debian play box, so I think it
must have to do somehow with the version of dhcp in distro 5.1.1. When trying dhcp, resolv.conf did have the interent dns servers?
So, still at a loss of what I forgot to check.

Joe

[tannenba]

Ok, downloaded the dvd for 5.3.1 and tried it on my lamp server in which DHCP works fine.
It would not work. Had to manually set it up. Also I believe it is asking for a specific IP:
192.168.0.49 and my router has resevered IPs per MAC which may be the problem. Where
would it get the address to ask for? My router's log says it offered 192.168.0.5 which is
resevered for the MAC of the machine. The router received the request then got acked on
the reply.

Again, the Debian DHCP works without a hitch on this same box.????

Joe

[tannenba]

Could it be the dhcp server is trying to use the interface? Where are the runlevel start-stop cmds?
rc0.d thru rc6.d are all about empty?

No syslog??

dmesg thinks the interface is up, doesn't say what address it recieved.

thx,
joe

[Suppi]

Thanks for your help, Harry.
Even though it looks like a DNS-problem, I think it's something else. My assumption is based on the following:
- 'dig www.heise.de' works fine with the router acting as DNS. The name gets resolved to IP-address
- I can browse to certain websites, like www.essen.de, so DNS seems to work for them to
- I monitored the network traffic using sniffit. Packages are exchanged between the correct IP-addresses

To me, this does not look like an DNS problem, but I have absolutely no idea what else it could be.
I manually set the DNS to my DSL-providers DNS as you proposed. No luck. Dig works, ping works, browsing does NOT work :-(

Any other ideas????
Suppi

[Harry Kuhman]

Could it be an IPV6/IPV4 problem? Not really sure what you next step should be, but I'll give it some thought.

[Suppi]

Hmm, that's what I thought too.
There are some hints on the web that Iceweasel and Konquerer have problems with ipv6.
I'll try using a different browser.
But I have no idea how to track down an ipv4/v6 problem. Any clues?


Suppi

BTW, this works too ( thus it's probably a browser problem ):
telnet www.heise.de 80
GET / HTTP/1.1

[Suppi]

Disbling ipv6 in iceweasel did not help ( type about:config in the adress bar and filter for ipv6 )
Neither did changing to lynx.
The problem was one of the routers ( from Digitus ) I used. After removeing it, everything was fine.
Now I'm using a SMC Barricade instead while writing this post from Iceweasel.

Very Surprising! I think it's time for a Linux certification of hardware like Microsoft did it.
Makes your choice much easier.

Suppi

[dram]

When using dhcp behind a router, what has worked for me for years when dns resolution problems cropped up, was to place my isp's primary and backup dns nameservers in the router's setup page, which helps bypass some dns issues for routers that are typically windows/mac-centric. Once the addresses are placed into the router itself, just restart networking, or reboot the computer.

This is usually the case when "my windows / mac computer works, but not linux" - assuming you don't have further issues with ipv6 or network connectivity in general.

If you don't know your isp's dns addresses, there are alternates like those seen at the bottom right of opendns.com. Since addresses can be altered in cached messages, verify them by visiting the site yourself.

Older routers sometimes had problems with ipv6, so one way to avoid that is to force Iceweasel to use ipv4 by typing "about:config" in the url bar, and searching for IPV6 in the filter. Change network.dns.disableipv6 to "true" by doubleclicking the preference name. I usually restart Iceweasel after that.

Note that I haven't touched upon globally disabling ipv6, only in Iceweasel. Putting the dns server addresses in the router itself has cured quite a few problems, especially in mixed-os environments - now everyone is on an equal footing because the router doesn't play with dns.