[pptp-server] Maximum number of users

Torge Szczepanek pptp-server at szczepanek.de
Sat Apr 13 02:46:34 CDT 2002

Am Sam, 2002-04-13 um 03.27 schrieb Igor Maciel Macaubas:
> But right now I have 100 users connected into my server, and it's impossible
> to connect.
> I get lot's of this error into /var/log/messages:
> Apr 13 00:29:35 vpn02 kernel: ppp_alloc failed
> Apr 13 00:29:36 vpn02 kernel: ppp: dev_alloc_name failed (-23)
> Apr 13 00:29:36 vpn02 kernel: ppp_alloc failed
> I saw into the linux kernel that ppp_alloc is a function of the kernel
> (drivers/net/ppp.c). So I suppose that I need to change the kernel source
> code to increase the number of connections. Please help me to increase this
> limit. I need this hurry.

Take a look at the kernel source at net/core/dev.c

There is a line:

If you need over 100 please also fix the algorithm...

In the for loop below that comment change the number 100 to 2048.

for (i = 0; i < 100; i++) {


for (i = 0; i < 2048; i++) {

Also increase the number of Unix PTYs to 2048. Otherwise you are stuck
with 256 users because of the limited number of Unix-PTYs.

Recompile your kernel and start with your new kernel.

You now have a maximum of 2048 users. ;-)

Torge Szczepanek

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