Date: Sun, 12 Apr 1998 22:24:19 -0700 From: Dima Dorfman <webmaster@zwb.net> To: freebsd-questions@FreeBSD.ORG Subject: Re: more than 32k users Message-ID: <3.0.5.32.19980412222419.00933dd0@207.213.224.25> In-Reply-To: <3.0.32.19980413005259.011936b0@peace.com.my>
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At 12:30 AM 4/13/98 +0800, you 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). > >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 >> >> > >To Unsubscribe: send mail to majordomo@FreeBSD.org >with "unsubscribe freebsd-questions" in the body of the message > > --- Thanks! Dima Dorfman - dima@zwb.net "640k ought to be enough for anybody." - Bill Gates, 1981 - Bill Gates To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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