concurrent connection problem

[eluser]jcavard[/eluser]
Hi,
I'm am lost here. I have a website hosted at 1and1.com and this morning I wasn't able to connect to my website. I contacted tech support and they happened to have blocked my IP!! They sent this email:

We have verified that your IP address XXX.XXX.XXX.XX was blocked by our firewall.

A successful connection is established after the server sends an acknowledgment in response to a synchronization request. Synchronization flooding occurs when the acknowledgment from the server was not receive causing your system to rapidly resend the requests multiple times. This is seen as a detrimental threat to the server's security causing your IP to get blocked.

Please try to reconnect 24 hours after your last connection attempt. To prevent this from reoccurring in the future, we strongly recommend to adjust your settings to less than 5 concurrent connections.

Now, my question is, how do I control the number of concurrent connections? and what creates concurrent connection?? I mean, I didn't change anything in the data access layer/queries. This site has been working fine for the past 10 month. What could have happend this morning? Does CI have an hidden setting for this? Does it even care about concurrent connection? Has anyone of you ever struggle with this? Maybe my question is not totally CI related, but since the website runs CI, I tought I'd ask here first..

thanks in advance.

[eluser]n0xie[/eluser]
SYN Flood is a form of DDOS attack. Since this has to do with the network layer (and thus is an hardware 'issue') your application can't do anything 'right' or 'wrong'. Your ISP/Host should have measures in place to try to combat DDOS attacks.

The only persistent connection your website most likely uses is to the database server. Since apache and mysql don't play nice together with persistent connections, you should have persistent connections set to FALSE (in your database config file), although this is probably totally unrelated to your problem.

[eluser]jcavard[/eluser]
[quote author="n0xie" date="1257824943"]SYN Flood is a form of DDOS attack. Since this has to do with the network layer (and thus is an hardware 'issue') your application can't do anything 'right' or 'wrong'. Your ISP/Host should have measures in place to try to combat DDOS attacks.

The only persistent connection your website most likely uses is to the database server. Since apache and mysql don't play nice together with persistent connections, you should have persistent connections set to FALSE (in your database config file), although this is probably totally unrelated to your problem.[/quote]

thanks man, at least, this sheds some light.
Last week, I tried to build a crawler that reads ±4000 html pages which is executed from that host, do you think this can be the culprit? I built and tested it last wednesday, but the Blocked IP problem only occured today...

Also, I noticed the 'pconnect' is enabled in the config file, I guess I should disable it?

[eluser]n0xie[/eluser]
[quote author="jcavard" date="1257825471"]
thanks man, at least, this sheds some light.
Last week, I tried to build a crawler that reads ±4000 html pages which is executed from that host, do you think this can be the culprit? I built and tested it last wednesday, but the Blocked IP problem only occured today...
[/quote]
It could be that you DDOS'ed your own machine. If you don't have some form of timing in place it could be that your connection couldn't handle all the 'answers' from the requests it was sending out.

Also, I noticed the 'pconnect' is enabled in the config file, I guess I should disable it?

I disable it by default on any Apache/MySQL stack. You should probably too.