> hello Linux users,
>
> We are a ISP in Germany and we're running a Linux based FTP Server.
> There are user accounts for each customer to upload into their www
> directory. Since we are rapidly growing I am curious if there exists an
> upper limit of the size of the passwd or the number of possible users on
> the linux box. Has anybody experience with that sort of constraints?
>
> Any help would be appreciated
>
> cheers
Hmm, don't know how this got onto linux-kernel, but ....
the upper limit on the numbers of uid's you can have is 65536, because uid
on linux is an unsigned short (0 to 2^16).
It's not a hard limit, but to remove it will be hard work, you'll have to
find every definition of it's type:
cd /usr/include
touch .emptyfile
find . -type f -exec grep -n uid .emptyfile {} \;
rm .emptyfile
that goes to /use/include, creates an emptyfile (with only one filename
grep, dosn't print the filename on matching files, so give it an empty
file to force it). Find's all files (type f), and exec's grep with the
'{}' replaced with each match found (ie everything under /usr/include
that's a file). It then removes the empty file ;). You get this:
./gnu/types.h:41:typedef unsigned short __uid_t; /* Type of user identifications. */
./gnu/types.h:52:typedef unsigned int __uid_t; /* Type of user identifications. */
./rpc/auth.h:120: uid_t aup_uid;
./rpc/auth.h:170: * AUTH *authunix_create(machname, uid, gid, len, aup_gids)
./rpc/auth.h:172: * int uid;
./rpc/auth.h:177:extern AUTH *authunix_create __P((char * __machine, uid_t __uid, gid_t __gid,
./rpc/auth.h:191:#define AUTH_UNIX 1 /* unix style (uid, gids) */
The first match is the important one, change that, and that should be it
(I have three definitions of it's type, two are in <gnu/types.h>, and one
in <_G_config.h>) if you look at <gnu/types.h>, it should be obvious why
the second is unimportant. All you have to do then is rebuild _every_
program that uses uids ....
if you change the type to unsigned int, you'll have 4294967296 uid's. I
think that'll be enough, at least until you start expanding into China ...
> --
> ===============================================
> Wilfried Geis Seitz GmbH
> willi@seitz.de Pforzheim
> Webmaster & Support Tel. 07231/584-200
> ===============================================
>
Bryn
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