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Google Maps: SYN Flood?

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Google Maps: SYN Flood?

By CoCaman

For the past few days (or is it weeks?) I have had a problem with my Internet connection. The connection randomly disconnected. I had no idea why. First I thought it was a problem with BitTorrent. But with blocked BitTorrent traffic the connection still wasn’t stable.

Today I invested some time and discovered something very interesting:

2007-07-10 23:30:00 – SYN Flood – Source:192.168.0.202,45066,LAN – Destination:66.249.93.104,20480,WAN

While using Google Maps, some pictures did not load correctly and Google displayed the default “no data for this level” image. And now I was close to solve this problem. It turned out that the following setting in Firefox is a problem for either my router of my modem:

network.http.max-persistent-connections-per-server

I can not set this value higher than eight. Looks like Google allows a lot of connections to their server, but sends back (bad?) SYN packets which cause troubles for my Netgear hardware.

15 thoughts on “Google Maps: SYN Flood?”

  1. Thanks so much for your post!

    I was trying to get the excellent Maemo Mapper application running on my Nokia 770 Internet Tablet but it just wouldn’t download any maps.. When I finally checked my wireless router logs it showed SYN flood attacks from Google! I wasn’t sure how to fix this until I read your post and then located a setting in the control panel called “Maximum incomplete TCP/UDP sessions number from same host”. I was able to increase this from 10 to 50 and bingo – problem solved.

    This setting was under DoS Detect Criteria, so if anyone else has this issue, look for denial of service settings in your routers control panel.

  2. Had the same problem at home with Google Maps (maps not loading correctly when zooming in, etc.) and first I thought it had something to do with Opera.
    But at work everything was ok, and Internet Explorer had the same problem with Google Maps at home (which it didn’t have before).
    So I looked into the log files of my SMC Barricade 7004VBR – and voila:
    **SYN Flood to Host** 192.168.0.221, 1429->> 209.85.137.91, 80 (from PPPoE Outbound)
    Increasing that “Maximum incomplete TCP/UDP sessions number from same host” to 50 solved the problem! Thanks to James for that 🙂

  3. Brilliant, seems to have worked for me too. Strangely though my laptop (IE6) which I was using via Wireless on same router never had the problem. Only affected my desktop (IE7) running wired.

    Thanks James.

  4. Finally I’ve fixed this!! Thanks ever so much for your help!

    I had a Belkin router and Google Maps was triggering the DoS security as you mentioned. All I had to do was visit http://192.168.2.1/firewall_spi_h.stm and change the setting…

    Now I can get back to coding up Google Maps API again, nice.

  5. Hi, I have had on ongoing problem with my belkin router flooding my dns server. My internet provider has shut me down a few times saying it,s a virus? I have run regedit and looked over the whole registry and have found nothing out of place. I have also done a complete virus scan with 3 different scanners, nothing. Does anyone know what the issue may be, any help would be appreciated. I am running Firefox 3 beta as my browser and we are fully firewall’d with encripted security so I have a hard time seeing it as a virus.

    Thanks in advance for any reply.

  6. By the way, I am a first time user of this site and am looking forward to any advice all you tech’s have out there. I am not a tech myself but have picked up a quite a bit over the years from more experienced comp techs and your advice and knowledge has helped allot. I am going to take a course a Duhram College and maybe one day I will be as good (if not better, LOL) than you. Then I can help us all.

    Thank you

  8. This solution worked out ok for me too.

    All of a sudden when browsing sites with a lot of pictures on em *cough* triggered the DDOS detecting in my Belkin router, google for example displayed ok.

    Didnt set it to 50 but to 20 to maybe not completely disable DDOS detection in the router.

  9. I completely disabled the firewall on my router, wich solved it.. Not a good solutions i guess.. But i couldn’t find the TCP/UDP settings.

  10. I’ve got the same problem, but have no idea what all these terms mean! Where can I find these TCP/UDP settings in IE7?

  11. I tried using your suggestions but no luck on either IE or Firefox. I finally shut off my software firewall, ZoneAlarm, and there were the maps. Now I have to find out what it is in ZoneAlarm that doesn’t like the maps. Satellite photos are okay. This is just a recent problem.

  12. Thankyou to everyone who suggested a solution! I’ve been having on and off-again issues with pages not loading in google image search for months now and this finally seems to have fixed it.

  14. Glenn, Thank you so much for the specific page to hit inside the Belkin, namely /firewall_spi_h.stm – that was the one small piece of information that I really needed. And like you, I have quite a lot of web pages using the Google Maps API.

    I have just checked one of my Maps pages & yep, it works just like a bought one!

  15. Increased “Maximum incomplete TCP/UDP sessions number from same host” to [20], which solved my “cannot-search-pictures-from-google-server-without-syn-flood-warning”-problem.

    Thanks a lot !!

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