On 26/09/17 11:55, Robert Bannocks wrote: > In respect of smtp_accept_max is there some upper limit and, for RH Linux, > how do I find out what this may be. There is presumably some Kernel limit, > but there are other things to consider too. Is this just something people > adjust hubristically or is there a more scientific approach?
I like the suggestion of hubris... The kernel limitation is essentially 64k minus any reserved via ip_local_port_range and ip_local_reserved_ports sysctls. Exim has a hardcoded limit of 4k (obviously individual distros could vary the code, but there's no support in build documentation for doing so. Memory is pre-allocated for connection-tracking purposes in proportion to the configured value, so you don't want it too high. The practical limit will be your system load, dealing with the number of concurrent connections. > > Same question for smtp_connect_backlog. This is just the value given with the "listen" syscall to the kernel. See the comments in the docs. > > Do not assume what I have inherited makes any sense. If your problem is with certain individual source systems, consider the smtp_max_per_host config option. -- Cheers, Jeremy -- ## List details at https://lists.exim.org/mailman/listinfo/exim-users ## Exim details at http://www.exim.org/ ## Please use the Wiki with this list - http://wiki.exim.org/
