D-Link DSL-G624T and LinkedIn.com

I bought a router D-Link DSL-G624T about a year ago. I was satisfied with the results and its configuration options, but at the end of last week its WiFi interface started to fail. Before I send it to the seller for repairing, I did a last hour test and it was working fine It’s clear that’s one of those intermitent issues that may make us crazy… so I connect it again and has been working without problems for two days…

But that’s not the main issue… About a couple of months ago, I opened an account on linkedin.com because a friend talk me well about that site, but I’ve been having problems of connectivity since then with linkedin.com so I even couldn’t login. I though it may be a problem with my ISP or so, and I’ve no problems with other pages, so I let it be thinking that one day it’ll begin to work fine…

And it did it. The day before yesterday on morning it was working fine, so I add some friends and colleages to my network. But in the afternoon it didn’t work yet. I did not realize then that it was working fine while I was using my other ADSL router instead of D-Link. But I did it this afternoon. After a few googling, I’ve found about a dozen of people with the same problem, but not solution.

D-Link DS-G624T

I did try a lot of configuration tweaks but after four hours I finally give up: I’ve demoted my D-Link router to a simple ethernet Hub and WiFi Access Point, connected to a little DSL router of just one port that’s now the keeper of the Internet Gates…

Now, linkedin works fine. Even other pages that was a bit slow, are faster now. It’s a pity, because I must now have two devices in the place of just one, and appart from this, I really like that d-link router, but… it should work! So…

Attached Files:

dlink-dsl-g624t
D-Link DS-G624T router, hub and WiFi Access Point

cuba

April 30th, 2009 at 12:50 pm

Hi, I’ve got the same issue. I’ve tried everything and I gave it up. I hope they let me know from linkedin support.

admin

April 30th, 2009 at 1:08 pm

Hola

The source of the problem is the router, so I do not think that linkedin support will do nothing to solve it, so…

Ian Stewart

May 1st, 2009 at 10:35 pm

There is a rule in the router’s firewall config that does a blanket set of the TCP MSS to 1360. If you telnet to the router and do an “iptables -L” you will see it like this…

Chain FORWARD (policy ACCEPT)
target     prot opt source               destination
TCPMSS     tcp  --  anywhere             anywhere           tcp flags:SYN,RST/SYN TCPMSS set 1360

I’ve had problems with this rule before, using a WiFi card with a small MTU, as it actually increases the MSS if it is already smaller than 1360 (I assume the intent of the rule is to decrease the MSS if it is larger than 1360). I don’t use this WiFi card anymore, and the rule doesn’t seem to be causing a problem, except with Linkedin.

Removing the rule fixes the Linkedin problem. In my case it was the first rule in chain FORWARD, so can be removed with the command

iptables -D FORWARD 1

Note that the rule will come back if the router is rebooted.

I raised the problem with DLink a while ago, their answer was to further reduce !!! the MTU.

Apart from this problem I have been happy with the product, just not with their support.

Fran

May 4th, 2009 at 9:36 am

Thanks for the information, Ian. I’ll try that on my own one ASAP and I’ll tell you about.

JOSEPH

June 8th, 2009 at 3:58 am

can anyone help? I want to creat rule for opening ports. But the rule is not being created.I can only add and apply once it is created.Y it is not seeing in the available rules once I made it?

Lim Afriyadi

June 10th, 2009 at 2:49 am

Hei Ian Stewart thanks for the information, I have the same problem and using DLINK DSL 520T,
I just did as you said above and it worked. Thank you very much.

Andrew

June 16th, 2009 at 1:36 pm

Ian you are a genius.
Works for me mate - thanks a bunch!
I wonder if iptables-save can be used to make if persistent…

Adrian

July 4th, 2009 at 6:08 am

Ian, likewise the instructions got me back to using 1 machine. Brilliant. Good one matey.

Patrick

July 14th, 2009 at 1:42 pm

This fixed the same issue for me, with a D-link DSL-G604T and linkedin.com. Thanks a lot for the suggestion.

July 24th, 2009 at 4:16 pm

Finally I’ve checked Ian Stewart’s workaround and it works for me also. Thanks Ian!

About making it permanent, I do not know how, but at least I think that I can do some scripting to remove the rule automatically from my laptop through telnet everytime I boot it.

John P

September 2nd, 2009 at 10:15 pm

Thanks Ian, your tip was great… I knew it had something to do with the D-Link DSL-G624T I am using since I could only connect to LinkedIn through a proxy… telnet solved it as you suggested. Great help!

MattL

September 3rd, 2009 at 12:15 am

I wonder if you can help a hapless Mac User also! Have a D-Link DSL-502T ADSL modem and a D-Link Wireless router DI-624S and very much the same problem with Linked-in. Tried Safari and Firefox on Mac 10.5, both wirelessly (using the 624S) and without (direct into the 502T). I know my way round the Mac, but if anyone can help with some step-by-step instructions on how I can effect the same ‘fix’, that would be great. I also have a PC laptop I could use to connect to the Router, but as I’m not PC savvy, some step-by-step would be very much appreciated!

Thanks a million!!!

nicolasc

October 27th, 2009 at 9:26 am

Hi,

i have the same problem with my setup Dlink 624T (ADSL) + Dlink Di-624+ (additional switch)
I can use Linkedin behind the 624T but if I connect my PC on the additional switch , then i can not access linked.

I have opened up Telnet on the DI 624+ using virtual server setup page (IP = fixed IP of the Pc I am using, tcp, port 23/23, always enabled)
I have either added the port 23 in the Pc firewall exception (XP SP2) or removed the firewall,

From the shell prompt of the PC, I can NOT telnet onto the DI-624+

Fionn

October 29th, 2009 at 10:03 pm

Thank you, Ian — I’ve been struggling with this issue re: LinkedIn for literally *years*, and there it was in your comment. A quick telnet into my D-Link DSL-G604T, and an update to the iptables, et voila’ — the problem is solved.

How on earth did you figure this one out / how did you know to go to the iptables in busybox???

Kudos to you, friend.

Thanks!

Jose Luis Domingo Lopez

November 15th, 2009 at 11:24 pm

Hi guys,

I’ve been experiencing this problem for _years_ now, but recently I had the need to use LinkedIn on a more daily basis, so starting from this thread I investigated further to apply a better solution than the ones previously shown here. The idea is the same, LinkedIn + iptables on the D-Link router seems a broken mix, so some rules are needed to avoid LinkedIn traffic
being dropped/trimmed/modified by the D-Link iptables’ rules.

The easier fix for me that avoided breaking other web sites was creating a new chain, and redirect all incoming traffic from LinkedIn to that new chain of rules. Then I add just two rules to that chain, first the one suggested here, and then a simple ACCEPT to prevent packages from
being reinserted into the INPUT chain, where they would be modified in a way that LinkedIn stops working. The full command line to use from the D-Link router (DSL-504T here) is the following:

iptables -N LINKEDIN
iptables -I FORWARD 1 –destination 64.74.98.80 –jump LINKEDIN # http://www.linkedin.com
iptables -I FORWARD 2 –destination 213.244.185.0/24 –jump LINKEDIN
iptables -I LINKEDIN 1 –protocol tcp –tcp-flags SYN,RST SYN -j TCPMSS –clamp-mss-to-pmtu
iptables -I LINKEDIN 2 –jump ACCEPT

Adapt this to your specific D-Link hardware configuration so to insert the jump rule just before the one that mangles the TCPMSS.

Hope this helps,and thank you for the original information.

Fran's blog