Re: maximum number of outgoing connections

Igor Sysoev wrote:
It seems that FreeBSD can not make more than

net.inet.ip.portrange.last - net.inet.ip.portrange.first

simultaneous outgoing connections, i.e., no more than about 64k.

If I made ~64000 connections 127.0.0.1:XXXX > 127.0.0.1:80, then
connect() to an external address returns EADDRNOTAVAIL.

net.inet.ip.portrange.randomized is 0.

sockets, etc. are enough:

ITEM SIZE LIMIT USED FREE REQUESTS FAILURES
socket: 356, 204809, 13915, 146443, 148189452, 0
inpcb: 180, 204820, 20375, 137277, 147631805, 0
tcpcb: 464, 204800, 13882, 142102, 147631805, 0
tcptw: 48, 41028, 6493, 11213, 29804665, 0

I saw it on 6.2-STABLE.



In an ideal world (Not sure if this is quite correct for FreeBSD) TCP connections are tracked with a pair of tupels source-addr:src-port -> dst-addr:dst-port

As your always connecting to the same destination service 127.0.0.1:80 and always from the same source IP 127.0.0.1 then you only have one variable left to change, the source port. If you where to use the hole of the whole of the port range minus the reserved ports you would only ever be able to make 64512 simultaneous connections. In order to make more connections the first thing that you may want to start changing is the source IP. If you added a second IP to you lo0 interface (say 127.0.0.2) and used a round robin approach to making your out bound connections then you could make around 129k outbound connections.

I am not sure if there are any other constraints that need to be taken into account such as the maximum number of sockets, RAM etc....

Tom
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