.\" Thanks to Alan Silverstein for help with the manual entry.
pathalias, makedb \- electronic address router
.\" the -g option is for pathparse. it's not really used by pathalias.
computes the shortest paths and corresponding routes from one host
(computer system) to all other known, reachable hosts.
reads host-to-host connectivity
information on standard input or in the named
host-route pairs on the standard output.
output and creates or appends to a
Ignore case: map all host names to lower case.
By default, case is significant.
Print costs: print the path cost (see below) before each host-route pair.
Verbose: report some statistics on the standard error output.
.\" the -g option is for pathparse and is not for public consumption (yet!).
Dump the edges of the graph into the named file.
discovers the local host name in a system-dependent way.
Declare a dead link, host, or network (see below).
is of the form ``host1!host2,'' the link from host1 to host2
is treated as an extremely high cost (\fIi.e.\fP, \s-1DEAD\s0) link.
that host is treated as dead
and is be used as an intermediate host of last resort on any path.
is a network name, the network requires a gateway.
Trace input for link, host or network on the standard error output.
Append to an existing database;
Identify the output file base name.
.SS \fIpathalias\fP Input Format
A line beginning with white space continues the preceding line.
Anything following `#' on an input line is ignored.
A list of host-to-host connections consists of a ``from'' host in column 1,
followed by a comma-separated list of ``to' hosts, called
A link may be preceded or followed by a network character to use
Valid network characters are `!' (default), `@', `:', and `%'.
A link (and network character, if present) may be
followed by a ``cost'' enclosed in parentheses.
arithmetic expressions involving numbers, parentheses, `+', `\-', `*',
The following symbolic costs are
\s-1LOCAL\s0 25 (local-area network connection)
\s-1DEDICATED\s0 95 (high speed dedicated link)
\s-1DIRECT\s0 200 (toll-free call)
\s-1DEMAND\s0 300 (long-distance call)
\s-1HOURLY\s0 500 (hourly poll)
\s-1EVENING\s0 1800 (time restricted call)
\s-1DAILY\s0 5000 (daily poll, also called \s-1POLLED\s0)
\s-1WEEKLY\s0 30000 (irregular poll)
is a very large number (effectively infinite),
are \-5 and +5 respectively,
for baud-rate or quality bonuses/penalties.
These symbolic costs represent an imperfect measure of bandwidth,
monetary cost, and frequency of connections.
For most mail traffic, it is important to minimize the number
of intermediaries in a route,
a default of 4000 is used.
For the most part, arithmetic expressions that mix symbolic constants
if a host calls a local neighbor whenever there is work,
and additionally polls every evening,
down princeton!(\s-1DEDICATED\s0), tilt,
princeton topaz!(\s-1DEMAND\s0+\s-1LOW\s0)
topaz @rutgers(\s-1LOCAL\s0)
If a link is encountered more than once,
the least-cost occurrence dictates the cost and network character.
Links are treated as bidirectional, to the extent that a
reverse link is assumed unless better information is available.
The set of names by which a host is known by its neighbors is
Aliases are declared as follows:
The name used in the route to or through aliased hosts
is the name by which the host is known
to its predecessor in the route.
Fully connected networks, such as the
The host-list may be preceded or followed by a routing
character, and may be followed by a cost:
princeton-ethernet = {down, up, princeton}!(\s-1LOCAL\s0)
\s-1ARPA\s0 = @{sri-unix, mit-ai, su-score}(\s-1DEDICATED\s0)
Connection data may be given while hiding host names
private {host, host, ...}
will not generate routes for private hosts, but may produce routes
The scope of a private declaration extends from the declaration to the end of
the input file in which it appears.
It is best to put private declarations at the beginning of the appropriate
A list of host-route pairs is written to the standard output,
where route is a string appropriate for use with
rutgers princeton!topaz!%s@rutgers
The ``%s'' in the route string should be replaced by the
user name at the destination host.
(This task is normally performed by a mailer.)
the name of a network is never used in
Thus, in the earlier example, the path from down to
up would be ``up!%s,'' not ``princeton-ethernet!up!%s.''
A network is represented by
a pseudo-host and a set of network members.
Links from the members to the network have the weight given in
the input, while the cost from the network to the members is zero.
If a network is declared dead on the command line (with the
the member-to-network links are marked dead,
which discourages paths to members by way of the network.
If the input also shows a link from a host to the network,
then that host will be preferred as a gateway.
Gateways need not be network members.
is declared dead on the command line
hosts will use csnet-relay as a gateway.
discourages forwarding beyond dead networks.
A host or network whose name begins with `.' is called
Domains are presumed to require gateways,
The route given by a path through a domain is similar to
that for a network, but here
the domain name is tacked onto the end of the next host.
Subdomains are permitted.
\&.\s-1EDU\s0 = {.\s-1BERKELEY\s0}
ernie ...!harvard!ernie.\s-1BERKELEY\s0.\s-1EDU\s0!%s
Output is given for the nearest gateway
\&.\s-1EDU\s0 ...!harvard!%s
Output is given for a subdomain if it has a different
route than its parent domain, or if all of its ancestor domains are private.
database from the standard input or from the named
(\fIMakedb\fP replaces the obsolete
which is no longer recognized.)
Input is expected to be sequence of
each consisting of a key field and a data field separated by a single tab.
If the tab is missing, the data field is assumed to be empty.
.ta \w'/usr/local/lib/palias.{dir,pag} 'u
/usr/local/lib/palias.{dir,pag} default dbm output
newsgroup mod.map likely location of some input files
available from newsgroup mod.sources (if not in the C library).
The order of arguments is significant.
can generate hybrid (\fIi.e.\fP ambiguous) routes, which are
abhorrent and most certainly should not be given as examples
Multiple `@'s in routes are prohibited by many mailers, so
resorts to the ``magic %'' rule when appropriate.
This convention is not documented anywhere, including here.
Domains constitute a futile attempt to defeat anarchy and otherwise
Steve Bellovin (ulysses!smb)
Peter Honeyman (princeton!honey)