Date: Mon, 13 Apr 1998 08:16:45 -0400 (EDT) From: Steve Hovey <shovey@buffnet.net> To: chas <panda@peace.com.my> Cc: rotel@indigo.ie, freebsd-questions@FreeBSD.ORG Subject: Re: more than 32k users Message-ID: <Pine.BSI.3.95.980413081616.24761L-100000@buffnet11.buffnet.net> In-Reply-To: <3.0.32.19980413005259.011936b0@peace.com.my>
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On Mon, 13 Apr 1998, chas wrote: > Sorry, this just makes me wonder : > > If yahoo is using FreeBSD for its services (and I presume > that that is its free email service), how could they ramp > up to millions of users all supposedly on the same machine > (since everyone has the email address : user@yahoo.com). They could have emailers chaining (what doesnt match on mahcine gets forwarded to B etc) > > I'm sure they're using IMAPd (beats DB programming for > managing folders etc) so they would have had to get around > any limit on the number of users on a machine. > > As for disk-space, my mind boggles. > > chas > > > > >On Apr 11, 8:56pm, Steve Hovey wrote: > >} Subject: more than 32k users > >> > >> I know this has been asked before, but Ill be dipped if I can find the > >> answer. > >> > >> Is it possible to increase the maximum number of unix ids over 32k so that > >> one can have over 32k users in /etc/passwd? > > > >>From looking at the header files I see that uid_t (the data type > >used to represent the UID in the kernel and elsewhere) is an unsigned > >32 bit integer meaning that this is possible in theory as long as > >no programs have assumed anything about the size of uid_t. pwd_mkdb > >doesn't like UID's > USHRT_MAX, but will allow you to use them. > > > >I have created a user with UID = 100000, and it certainly doesn't > >break anything instaneously :) > > > >[root@ginseng /etc]# tail -1 /etc/passwd > >foo:*:100000:100000:Niall Smart,Somewhere > Someplace:/home/nsmart:/usr/local/bin/zsh > >[root@ginseng /etc]# su foo > >[foo@ginseng /etc]$ id > >uid=100000(foo) gid=100000 groups=100000 > > > >You might like to ask in -hackers about this, if you're in an > >environment where you can experiment with this then I'd so go ahead > >and try it. > > > >Beware that any programs which do not use uid_t portably (i.e. > >assume it can only go up to 65536) will probably have security > >problems if you use uid's > 65536 because the variable they > >store the UID in will wrap around. > > > >So, in summary, there is nothing preventing this on the kernel > >side and correctly written programs should handle it, but be > >careful - try and find someone else who is doing this! :) > > > >Niall > > > >-- > >Niall Smart. Microsoft Suck. See www.freebsd.org for details. > >echo "#define if(x) if(!(x))" >> /usr/include/stdio.h > > > >To Unsubscribe: send mail to majordomo@FreeBSD.org > >with "unsubscribe freebsd-questions" in the body of the message > > > > > ------------------------------------------------------------------ Steve Hovey Chief Engineer BuffNET More Than Just a Connection! ------------------------------------------------------------------ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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