netplan - IP server for plan(1) appointment lists
netplan [-f] [-d] [-v] [-a]
netplan is an IP server that serves calendar data to plan(1) programs.
It maintains the /var/lib/plan/netplan.dir directory, that contains
calendar files and an access list file. plan users can name files and
hosts in their file list dialog, which causes plan to establish a
connection to netplan on the given host and request data from the file.
netplan handles multiple connections to the same file, sequences
updates to files such that no data can be lost if multiple simultaneous
updates are requested, and notifies connected plan programs of changes
so they can update their displays.
-f Runs in the foreground. This is useful for debugging.
-d Debug mode. This implies -f. All connections and transactions
are logged to the terminal. Among other things, the program
version and file locations are printed.
-v Verbose. Together with -d, the verbosity of the log messages is
increased to include data requests. this can generate large
numbers of messages.
-a Authentication via IDENTD (RFC 1413) is mandatory. If
authentication fails, map the client to UID/GID NOBODY. Use this
only if all connecting client hosts (running plan or pland )
support the identd authentication service (you can find out by
running ‘‘telnet clienthost 113’’; if telnet reports
‘‘Connected’’ type Ctrl-D, clienthost support identd). If a
client host that does not support identd connects to a netplan
server run with -a, it will have no or restricted access. Also,
if you use -a, you must have a netplan-acl file or no access is
granted to anybody; see below.
All files accessible to netplan are stored in the
/var/lib/plan/netplan.dir directory. netplan will not access any files
that are not in this directory or in subdirectories of this directory.
It will also refuse to access softlinks and files with multiple hard
links. This prevents users from linking normally inaccessible files to
netplan.dir and accessing them through netplan . Finally, files
beginning with a dot are rejected to prevent access to netplan-acl and
other future configuration files.
/etc/plan/ may also contain a file netplan-acl that controls which user
can access which file. If the file is missing, no restrictions are
imposed unless netplan is started with the -a option, in which case no
access to any file is granted. The syntax for netplan-acl file is a
sequence of rules like this:
name | owner | * : [permit | deny] [read] [write] [delete]
[[user | group | host] data [data...]]
name is the file the rule applies to; an asterisk (*) applies to all
files. The special name owner applies to the file by the name of
current user, containing that user’s ‘‘own’’ appointments.
Permit is the default. If none of read, write, or delete are specified,
all three are the default. The netmask applies to the client’s IP
address. The default netmask is 255.255.255.255. data is one or more
user names or numerical UIDs, group names or numerical GIDs, or host
names or numerical n.n.n.n IP addresses for user, group, and host
clauses, respectively. In user clauses, values of the form user@host
are also accepted. Symbolic names will be looked up on the server host
(where netplan is running) and will be converted to numerical values
while the ACL file is read. This assumes that all hosts agree on
symbolic and numeric user, group, and host IDs; the plan/netplan
protocol always uses numerical IDs and assumes that they correspond to
the same symbolic names on both hosts. If no user, group, or host
keyword and data list is specified, the meaning is ‘‘any’’.
Trailing n=0 IP address components are not assumed to denote nets; use
the netmask specifier for subnet masking. All whitespace is ignored.
Pound signs (#) introduce comments that extend to the end of the line.
*: permit read
*: permit write host daphne
vacation: permit write user 207
thomas: deny user *
thomas: permit read write delete user 207 208
announce: permit write netmask 255.255.255.0 host 10.0.1.0
first permits reading all files to everybody, and restricts write
access to users on host daphne. The third line permits write access to
the file vacation to user 207, in addition to the read access permitted
in lines 1-2. Next, read and write access for file thomas is granted
to users 207 and 208 only. Finally, the file announce can be written by
all users on hosts whose network address begins with 10.0.1. Trailing
".0" parts need not be entered. The netmask basically specifies which
bits of the client address are compared; all addresses are binary-ANDed
with the netmask before comparison.
When opening a file, the rules are scanned sequentially. All rules
whose file part (before the colon) matches the opened file, set or
clear permission flags for reading and writing, based on the identity
of the plan client as given by his user ID, group IDs, and IP address.
The final settings of these flags determine the permissions of the file
for the client. The final permission setting is the AND result of the
permissions derived for the host/netmask, and user/group part,
netplan tries to verify the identity of the client user with the IDENTD
(RFC 1413) protocol. If the identification succeeds, the client
username is mapped to UID and GIDs per the local passwd and group files
on the server host. If RFC 1413 identification is unsuccessful,
netplan trusts the (numerical) identity provided by the client.
If the -a option is given on the invocation of netplan, RFC 1413
identification becomes mandatory, and a failed identification will map
the client to the NOBODY UID and GID.
Note that although the ACL syntax was roughly patterned after TIS fwtk
firewall configuration files, the code and interpretation is rather
netplan trusts IP addresses to determine host (network) access
restrictions. If IP addresses cannot be trusted, host access
restrictions become meaningless.
Without RFC 1413 authetication, netplan trusts whatever user id and
group id the client provides. If netplan is used through the regular
plan front-end application, the access list file specifications are
honored, but any half-witted programmer can fake his identity using
telnet or a hacked version of plan (the sources are, after all, freely
available) to circumvent the access restrictions.
If RFC 1413 authentication is mandatory (-a flag), netplan still trusts
whatever the remote identd provides. If you cannot trust root on the
remote host, you cannot trust the identd result. (And if you cannot
trust IP addresses, you effectively cannot trust the remote root any
In this version of netplan, no challenge-response encryption is used to
guarantee secure transactions. This may or may not change in future
versions. In this version, access lists provide only a moderate
The location for /etc/plan/netplan-acl is specific to Debian GNU/Linux.
For compliance with FSSTND/FHS, it has been moved there from its
traditional /var/lib/plan/netplan.dir/.netplan-acl location. The
program still accesses that file via a symlink located at the
Thomas Driemeyer <firstname.lastname@example.org>
Please send all complaints, comments, bug fixes, and porting
experiences to me. Always include your plan version as reported by
"plan -v" in your mail. To be added to the mailing list, send mail to
email@example.com with the line "subscribe plan" (without the quotes)
in the message body (not the subject).
See http://www.bitrot.de/plan.html for new releases.