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Posted to users@tomcat.apache.org by Rau NF <nf...@yahoo.com> on 2003/09/19 21:16:43 UTC
tomcat - thread per connection model
Hi - Since tomcat implements a thread per connection
model (as per the spec), would it be open to a DoS
attack if it does not have an Apache server in front
of it ? ie keep all threads busy servicing slow
requests and valid users can't get in.
Assuming there is no apache server in front of tomcat
and tomcat is serving everything, what's a reasonable
connection timeout value? I know this is application
specific but it would be interesting to hear about
this. The goal obviously is to serve as many users as
possible without having to create too many threads.
Thanks in advance
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Re: tomcat - thread per connection model
Posted by Bill Barker <wb...@wilshire.com>.
"Rau NF" <nf...@yahoo.com> wrote in message
news:20030919191643.62672.qmail@web60108.mail.yahoo.com...
> Hi - Since tomcat implements a thread per connection
> model (as per the spec), would it be open to a DoS
> attack if it does not have an Apache server in front
> of it ? ie keep all threads busy servicing slow
> requests and valid users can't get in.
On my tests, Tomcat stands up pretty well to a DoS attack. It will become
slow if I have one machine saturate it with requests, but they all
eventually get served. Tomcat 5 has additional logic to throttle
connections if the load becomes high, so I'd guess that a DoS attack against
it (with the default settings) is almost impossible (you would need a DDoS
attack, since one machine couldn't maintain the concurrency necessary to
shut Tomcat down).
>
> Assuming there is no apache server in front of tomcat
> and tomcat is serving everything, what's a reasonable
> connection timeout value? I know this is application
> specific but it would be interesting to hear about
> this. The goal obviously is to serve as many users as
> possible without having to create too many threads.
I tend to use 5sec (which is 5000 in server.xml), since most of my apps
write back very quickly. Some people prefer 15sec; The current default for
Tomcat 4 is 1min. Like anything else, it depends on your app. If you
typically start sending back data that includes links to images/style-sheets
very quickly, then you want a low number. Even if not, I prefer to set
disableUploadTimeout="false" to use the longer time to read the request
body.
>
> Thanks in advance
>
> __________________________________
> Do you Yahoo!?
> Yahoo! SiteBuilder - Free, easy-to-use web site design software
> http://sitebuilder.yahoo.com
Re: tomcat - thread per connection model
Posted by Bill Barker <wb...@wilshire.com>.
"Rau NF" <nf...@yahoo.com> wrote in message
news:20030919191643.62672.qmail@web60108.mail.yahoo.com...
> Hi - Since tomcat implements a thread per connection
> model (as per the spec), would it be open to a DoS
> attack if it does not have an Apache server in front
> of it ? ie keep all threads busy servicing slow
> requests and valid users can't get in.
On my tests, Tomcat stands up pretty well to a DoS attack. It will become
slow if I have one machine saturate it with requests, but they all
eventually get served. Tomcat 5 has additional logic to throttle
connections if the load becomes high, so I'd guess that a DoS attack against
it (with the default settings) is almost impossible (you would need a DDoS
attack, since one machine couldn't maintain the concurrency necessary to
shut Tomcat down).
>
> Assuming there is no apache server in front of tomcat
> and tomcat is serving everything, what's a reasonable
> connection timeout value? I know this is application
> specific but it would be interesting to hear about
> this. The goal obviously is to serve as many users as
> possible without having to create too many threads.
I tend to use 5sec (which is 5000 in server.xml), since most of my apps
write back very quickly. Some people prefer 15sec; The current default for
Tomcat 4 is 1min. Like anything else, it depends on your app. If you
typically start sending back data that includes links to images/style-sheets
very quickly, then you want a low number. Even if not, I prefer to set
disableUploadTimeout="false" to use the longer time to read the request
body.
>
> Thanks in advance
>
> __________________________________
> Do you Yahoo!?
> Yahoo! SiteBuilder - Free, easy-to-use web site design software
> http://sitebuilder.yahoo.com
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