D-Link DSL-604T problem

I'v been practically forced to use D-Link's DSL-604T wireless router. My computer is connected to it by a standard cable, so you can forget about all the wifi things. This router has problems with Linux, and I was able to solve my main issue but now I'v forgotten it. Anyhoo, I'v been using Linux for quite a while, so I know some things. The problem is, that this router doens't let Linux computers out to SHH, telnet, FTP (you can download via a browser but no way in hell can you make a connection with a ftp client or upload to speak of), other IM's than MSN (which in the end doesn't mind, don't have contacts on any of the others anyway), and most of all: IRC.

Ages ago I was able to find a post where someone suggested that this could be fixed by adding a line in a configure file. When I did this I got my IRC working, and that here is my goal this time. If anybody of you knows what line I should put and where, please tell me, I'd really appreciate it.

On the other hand, if someone knows how to get rid of this problem once and for all I'd appreciate it more!

PS. Switching router is a thing I'd like to do but it isn't up to me, and this isn't a matter of router configuration, and also, I know other D-Link routers have a similiar problem, but they haven't really worked. Maybe I'v done something wrong?

You can try to go to the router conf page,I think it is 192.168.0.1 and set up the linux box on the DMZ and then run a firewall on it.

Thanks for your effort.

Unfortunately that doesn't help. The issue here is a bug on the router, which causes that Linux boxes don't have a complete access to the internet. This bug is so far present on other D-Link models and is not (from what I'v heard) fixable from the router configuration. In some models the bug can be bypassed by some fixes on your Linux box, but these don't seem to work on this model. But there was some line in some of the networking config files that happened to let the IRC through. Got a flashback as you can see Oh and the line had something to do with an IP address... I added my IP address at some part... But where and how? Hope somoby can help. I really want to get back to IRC..

I've a DSL-G604T and have no problems with FTP, Bittorrent, etc., on my Linux box.

What's the bug?
The only problem I know of is IPv6 DNS lookups - disabled that and everything works well.

Which firmware do you have on the Dlink?

What firewall do you have running on the linux box?

-RikD

Well my box reads DSL-604T, not DSL-G604T, not sure if it matters tho. Well there is no firewall running on my linux computer and the firmware is V1.00B02T02.TA.20050301 and where do I disable this IPv6 DNS lookups?

Not aware of a DSL-604T, mine says DSL-G604T

But, that said you FW version string looks similar to my G604T one. Wonder if they are the same box or not - maybe you can check it out.

For the G604T, there are a number of different current ones depending on country - UK, Oz, Italy, Spain, etc. I find the Ozzie FW (V1.00B05.AU) the most stable, but I do miss the ability to set static IPs (fixed by setting the DHCP server range). And the only problem it has now is to set it up for good P2P. I just run the following on the box (once I telnet)

cd /proc/sys/net/ipv4/netfilter/
echo 2048 > ip_conntrack_max
echo 50 > ip_conntrack_generic_timeout
echo 6 > ip_conntrack_tcp_timeout_close
echo 5 > ip_conntrack_tcp_timeout_close
echo 120 > ip_conntrack_tcp_timeout_close_wait
echo 1200 > ip_conntrack_tcp_timeout_established
echo 120 > ip_conntrack_tcp_timeout_fin_wait
echo 60 > ip_conntrack_tcp_timeout_time_wait
echo 10 > ip_conntrack_udp_timeout

And finally,
For IPV6 I meant on your linux box. If your box does a DNS lookup for an IPv6 address, it fails. This could be your problem with FTP, SSH, etc.

-RikD.

ok done those commands in the box, nothing. But how do I disable the IPv6 dns lookup then?

I think it depends on distro....

On Suse I did 2 things to disable
1. via the Yast /etc/sysconfig editor, under Network/Hardware/Config/USE_IPV6 to NO
think this edits (among other things) sysctl.conf to set net.ipv6.conf.all.forwarding to false
2. edit modprobe.conf to ensure ipv6 is not loaded by default, i.e. commented out "install ipv6 /bin/true"

That worked for me.

If using KDE there may be some settings there. And in Mozilla on the about:config page set network.dns.disableIPv6 to true. Although for me the 2 points above were enough to put an end to it.

Another (and probably better) idea - try pointing pointing to known good DNS Servers, don't use the DLINK DNS relay. Study the log on your DLINK to get servers and set these in your /etc/resolv.conf

RikD.

hi

I have had similar problems with a G604T router on my Debian box. Really strange symptoms (ie can access a site by ftp using web browser, but not from command line, can ping hosts but not ftp/telnet/ssh them, can ssh/telnet/ftp by IP address but not by hostname. smtp server could not connect to smarthost .... ).

The problem is the routers DNS relay service. It;s buggy. I proved it by getting out a packet sniffer. DNS replies were coming back OK but telling the linux box to use IP address 192.168.1.1, the router itself, and other nonsensical addresses like 1.0.0.0. Never had problems with a windows box for some reason.

Basically you need to turn off DHCP and DNS relay and set your network up manually. First of all look in the logs for the router and see what DNS servers it is getting from your ISP when it connects - write them down, and config those manually on all your boxes. Then manully assign an IP address (192.168.1.2, 192.168.1.3 ...) to each PC, give it a name, and add those as statically defined addresses in the router setup.

Do a google on "network config" if you're not sure, or ask here. There is loads of info.

Once you have this done right your boxes will boot a little quicker and your network will work better. And you will be able to use all ftp ssh and so on no problems.

cheers

Daniel

and BTW, I did do a firmware upgrade on the router as well - the gug was still there afterwards.

OK so how would the IPv6 turned off in Slackware? And how do I check wether I have it on anyway?

And danmcb do you mean that I would have to put up the WHOLE f*cking network up manually? 3 out of the 4 computers are windows comps and of two of those I'm not "priviledged" to fiddle with, so I don't really see that as that much of an possibility, concidering that I have tried to put my Linux computer on manual connection and I never got it working, I'm awful with networks.

And PS, the 1.0.0.0 problem is exactly what happens with IRC for example.

yes. It's your call, if you want to fix the problem, learn. If not, live with the problems - or try to get some help with DLink (I wish you luck with that), because it's their buggy firmware.

It isn't that much work. I'll give you a start - the rest you can find by Google:

You have to set theseparameters for each computer:

1. IP address
2. Gateway IP address.
3. Subnet mask.
4. DNS server(s).

On linux, those pieces of info live in these places:
1. /etc/network/interfaces
2. as 1
3. as 1
4. /etc/resolv.conf

On win98, you do it all by right clicking "network neighbourhood" and editing properties for the TCP/IP protocol.

Other OS's, Google.

It is also good to name each machine, and edit /etc/hosts for each Linux box so you can refer to them by name not IP. Something similar exists in the windows dir on a win box.

(That's approximately 150 words more than my original reply was going to be ...)

and BTW the only reason I responded was because I was having EXACTLY the symptoms you have, and wanted to help you out - it took me weeks to find out what the real problem was. At least I did the hard bit for you.

No need to turn off anything to disable the DNS on linux..

Just take the IP addresses of the DNS servers found in the log, and enter them in /etc/resolv.conf.

i.e.
nameserver a.b.c.d
nameserver e.f.g.h

where a.b.c.d and e.f.g.h are the IP addresses of the discovered primary and secondary DNS servers respectively..

Ensure any scripts run by your distro don't overwrite /etc/resolv.conf with dhcp. Check out /etc/dhpcd.conf or YaST in SuSE.

And hey presto - bypass the buggy DNS on the DLink..

-RikD

I don't know if the DNS relay on the dlink identifies the requests that it relays (and then screws up) by IP address or by port number - ie I don't know whether or not it will hijack a DNS request made directly to the server.

Never found out how to stop /etc/resolv.conf being overwritten by the DHCP process, if you can do that it may be simpler. Worth a try.