---------- Forwarded message ---------- From: Niklaus <niklaus@xxxxxxxxx> Date: Mar 9, 2007 2:52 PM Subject: Re: more than 65535 outbound connections To: David Lang <david.lang@xxxxxxxxxxxxxxxxxx> Cc: Florian Weimer <fweimer@xxxxxx> On 3/9/07, David Lang <david.lang@xxxxxxxxxxxxxxxxxx> wrote:
On Fri, 9 Mar 2007, Florian Weimer wrote: >> i read on the web that terry lambert has got 1.6 million simultaneous >> connection ? how is the way it is done. > > Multiple IP addresses, I guess. what must be unique is the four-parts of a connection source IP, source port, destination IP, destination port
what must be unique is the four-parts of a connection source IP, source port, destination IP, destination port
yes now lets take 2 dest machines , source ip is fixed , source port (2^16 - 1) destip is fixed (a.a.a.a and b.b.b.b) ,dest port(2^16 -1) each , for a connection we have one port used , say connection 1 is source ip,port 1 , a.a.a.a port 1 source ip,port 2 , a.a.a.a port 2 . . . source ip,port 65535 , a.a.a.a port 65535 so total of 65535 connections (assume traffic is still going on, a movie on a slow line dialup or 1kbps ) now if i try to open another connection (assume lots of file descriptors are present) to a.a.a.a what happens to b.b.b.b what happens i think both will not get established as the OS doesn't have any free source ports or am i wrong
as long as the set is unique any element can be re-used (a big webserver has one IP and port on the server side, but many IPs and ports on the client side) when you make a connection you have the option of not specifying the source IP and port (letting the OS/library pick ones for you). some libraries will not re-use the same source port for multiple connections, others will (with the appropriate options) if you want to have your program assign the source IPs and port itself you can do so (you may have to also give the library/os a flag that tells it you know what you're doing, and it's ok to let you re-use ports) David Lang
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