Q: Are there limits to the number of hosts to which a directory hierarchy can be exported, or granted root access?\
\
A: Yes. In release
\b 1.0
\b0 , one can export a hierarchy explicitly to at most
\b ten
\b0 different hosts. Likewise, one can permit selective root access to at most
\b ten
\b0 different hosts. This limit has been increased in
\b 2.0
\b0 , see the comments below. A line in
\f1 /etc/exports
\f0 might look like\
\
\f1 / -ro,access=host1:host2:host3,root=host3\
\f0 \
If there are more than ten hosts listed in the
\f1\b root=
\f0\b0 clause, an error message will be printed. If there are more than ten hosts in the
\f1\b access=
\f0\b0 clause, though, it will fail silently.\
\
If the number changes in the future, the change will be reflected in the
\f1 EXMAXADDRS
\f0 constant in
\f1 <nfs/export.h>
\f0 .
\gray333 (N.B. the
\f1 EXMAXROOTADDRS
\f0 constant is ignored in the code, currently; both
\f1 access=
\f0 and
\f1 root=
\f0 are governed by
\f1 EXMAXADDRS
\f0 .)\
\
\gray0 In
\b 2.0
\b0
\f1 EXMAXADDRS
\f0 and
\f1 EXMAXROOTADDRS
\f0 have been increased to 1024. You can thus explicitly export to up to 1024 different hosts in
\b 2.0
\b0 .\
\
The available workaround for this limitation is to provide global access, or more restricted access (i.e., access to ten or fewer hosts). To provide global access, one could use\
\
\f1 / -ro,root=host3\
\f0 \
One can also use a netgroup in place of, or in addition to, hostnames. From my experimentation, the real limitation is ten entries in the clause, regardless of whether those entries are netgroups, hostnames, or some combination. Entries in the