Re: automatic adduser/addgroup in postinst (was Re: fingerd)

[Ian Jackson <ian@chiark.chu.cam.ac.uk>]

Lukas Nellen writes (SuperCite undone):
>Ian Jackson <ian@chiark.chu.cam.ac.uk> writes:
>> This is a bug in the base system, I believe.  Our uid (and gid)
>> allocation structure is
>>   0-99       base system maintainer, allocated centrally
>>   100-999    allocated dynamically and locally by adduser (and so may
>>              not be preempted centrally) for system accounts
>>   1000-$     allocated dynamically for ordinary users
>>   65534      `nobody', allocated centrally
> 
> In many mixed environments, UIDs starting from 100 are used for
> ordinary accounts. How do you prevent clashes? Wouldn't it be safer to
> allocate UID's for system accounts starting from 65533 downwards? For
> all I know, that is less likely to cause problems in an heterogeneous
> network. 

The way you prevent clashes is by copying in a passwd file with the
uids you need allocated, or by reconfiguring adduser
(/etc/adduser.conf, I believe), before you install the packages which
make it allocate the uids.

Allocating system uids as high uids breaks the general assumption
which many old scripts (eg, arbitron) seem to use that system uids are
lower than user uids.

Ian.