Hi Martin,<div><br></div><div>dusting off the mental cobwebs, I believe the number of ports available in the kernel by default is 32k (32 * 1024), but that can be increased to 64k (65535) with the appropriate tuning. However I don't know if this applies to forwarding or just applications. </div>
<div><br></div><div>It also means that should the number of connections through the gateway be exceeded, you would also be unable to login remotely as this would require another port.</div><div><br></div><div>Note I have also only seen this as an issue on servers with massive numbers of connections (ie webservers for popular web sites)</div>
<div><br></div><div><br></div><div>Have you looked into more advanced iptables scripting to see if what you require is possible?</div><div><br></div><div>Cheers</div><div>Dylan</div><div><br></div><div><br></div><div><br>
<br><div class="gmail_quote">On 11 October 2011 14:16, Martin <span dir="ltr"><<a href="mailto:martin@ml1.co.uk">martin@ml1.co.uk</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
Folks,<br>
<br>
Anyone know this one?<br>
<br>
<br>
For a Linux box acting as a gateway between two networks, how can I<br>
limit the maximum number of simultaneous connections between the two<br>
networks? (No NAT, connecting two network segments with different IP<br>
ranges.)<br>
<br>
Or if it is doing NAT, can I limit the maximum number of NAT entries<br>
to refuse additional connections gracefully?<br>
<br>
And... Can I prioritise certain destination ports over others for<br>
being allowed one of the limited number of forwardings?<br>
<br>
<br>
There is "tc" which is ideal for doing bandwidth management. Is there<br>
any similar trickery for the maximum number of network<br>
connections/forwards?<br>
<br>
Aside: Out of curiosity, how many simultaneous connections can a Linux<br>
kernel handle? What is the limiting factor?<br>
<br>
<br>
Cheers,<br>
Martin<br>
<br>
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