Maximum number established TCP connection

Bill Moran wmoran at
Mon Mar 3 18:36:12 UTC 2008

In response to Patrick Dung <patrick_dkt at>:

> Hello
> I would like if there is a (countable) limit for the max TCP connection
> of a Apache web server.
> Suppose:
> 1. An apache web server serves a very big iso file.
> 2. 5000 people tried to connect to the apache server to get the iso
> file.
> 3. They connect to the server gradually (not 5000 people starting at
> the same moment). So that there will not be a problem caused by the TCP
> backlog limit.
> 4. There will be 5000 established TCP connections.
> Is it true that FreeBSD could handle 'unlimited' established TCP
> connections as long as it has enough CPU power and memory?

The FreeBSD limit on the number of open TCP connections is significantly
higher than the Apache limit on the number of concurrent HTTP sessions.
I believe Apache has a hard limit of 256.

Bill Moran

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