What was the sysctl value for net.ipv4.tcp_syn_max_backlog set to
while running this test? That's the value you are testing, not the
listen() queue size.
Ivan...
On 27 Nov 2002, Philippe Troin wrote:
> [Andi, I've CC'ed you since you're listed as the author of the `new
> listen' code in net/ipv4/tcp_ipv4.c]
>
> Seen on linux 2.4.20rc2.
>
> This program is always able to establish new connections to itself:
> the accept queue never fills up and connections always succeed
> (although they take quite some time after the first four):
>
> #include <stdio.h>
> #include <sys/types.h>
> #include <sys/socket.h>
> #include <netinet/in.h>
>
> int main(void)
> {
> int fd;
> struct sockaddr_in sin;
> socklen_t sinlen;
>
> if ((fd = socket(PF_INET, SOCK_STREAM, 0)) == -1)
> perror("socket"), exit(1);
>
> sin.sin_family = AF_INET;
> sin.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
> sin.sin_port = htons(0);
> if (bind(fd, (struct sockaddr*)&sin, sizeof(sin)) == -1)
> perror("bind"), exit(1);
> if (listen(fd, 1) == -1)
> perror("listen"), exit(1);
>
> sinlen = sizeof(sin);
> getsockname(fd, (struct sockaddr*)&sin, &sinlen);
>
> while (1)
> {
> int fdc;
>
> if ((fdc = socket(PF_INET, SOCK_STREAM, 0)) == -1)
> perror("socket"), exit(1);
> printf("%c", connect(fdc, (struct sockaddr*)&sin, sinlen) == -1
> ? 'F' : '.');
> fflush(stdout);
> }
>
> exit(0);
> }
>
> I've tried enabling and disabling tcp_syncookies, without any effect.
>
> The same program starts returning errors after two successful connects
> on Solaris and one on HP-UX. Linux keeps returning new connections...
>
> Phil.
> -
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------------------------------------------------------------------------ Ivan Pulleyn Sixfold Technologies, LLC Chicago Technology Park 2201 West Campbell Drive Chicago, IL 60612
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