How to turn OFF MaxStartups/SourcePenalties ?

[Brian Candler]

On 13/09/2026 20:36, Hendrik Visage wrote:
> Reading the manual page, I don't see how to totally turn off those
> functions as it keeps causing problems for my mass connections from
> some services that needs to do mass paralle connections over the
> latency links ;(
>
> I already use SSHGuard to successfully block any other "attacks" and I
> need to have these mass parallel sessions starting without SSHD
> interfering beyond RAM/CPU resources limits so where/how to totally
> turn of that functionality ?

The parent sshd process keeps an array of children. From sshd.c:

/* Allocate and initialise the children array */
static void
child_alloc(void)
{
         int i;

         children = xcalloc(options.max_startups, sizeof(*children));
         for (i = 0; i < options.max_startups; i++) {
                 children[i].pipefd = -1;
                 children[i].pid = -1;
         }
}

So you need to set MaxStartups to a suitably high number: there will be 
a fairly small RAM cost, but also linear searches through this array 
under various circumstances (e.g. to look for an unused slot on a new 
connection, or find the pid of a child when it terminates), so don't set 
it astronomically high.  Set it to the highest reasonable "mass" number 
of parallel connections you will allow.