NAME

proxymap - Postfix lookup table proxy server

SYNOPSIS


pprrooxxyymmaapp [generic Postfix daemon options]

DESCRIPTION

The pprrooxxyymmaapp(8) server provides read-only or read-write table lookup service to Postfix processes. These services are implemented with distinct service names: pprrooxxyymmaapp and pprrooxxyywwrriittee, respectively. The purpose of these services is:
· To overcome chroot restrictions. For example, a chrooted SMTP
server needs access to the system passwd file in order to reject mail for non-existent local addresses, but it is not practical to maintain a copy of the passwd file in the chroot jail. The solution:


local_recipient_maps =
    proxy:unix:passwd.byname $alias_maps
· To consolidate the number of open lookup tables by sharing
one open table among multiple processes. For example, making mysql connections from every Postfix daemon process results in "too many connections" errors. The solution:


virtual_alias_maps =
    proxy:mysql:/etc/postfix/virtual_alias.cf


The total number of connections is limited by the number of proxymap server processes.
· To provide single-updater functionality for lookup tables
that do not reliably support multiple writers (i.e. all file-based tables).

The pprrooxxyymmaapp(8) server implements the following requests:

ooppeenn _m_a_p_t_y_p_e_:_m_a_p_n_a_m_e _f_l_a_g_s Open the table with type _m_a_p_t_y_p_e and name _m_a_p_n_a_m_e,
as controlled by _f_l_a_g_s. The reply includes the _m_a_p_t_y_p_e dependent flags (to distinguish a fixed string table from a regular expression table).
llooookkuupp _m_a_p_t_y_p_e_:_m_a_p_n_a_m_e _f_l_a_g_s _k_e_y Look up the data stored under the requested key.
The reply is the request completion status code and the lookup result value. The _m_a_p_t_y_p_e_:_m_a_p_n_a_m_e and _f_l_a_g_s are the same as with the ooppeenn request.
uuppddaattee _m_a_p_t_y_p_e_:_m_a_p_n_a_m_e _f_l_a_g_s _k_e_y _v_a_l_u_e Update the data stored under the requested key.
The reply is the request completion status code. The _m_a_p_t_y_p_e_:_m_a_p_n_a_m_e and _f_l_a_g_s are the same as with the ooppeenn request.

To implement single-updater maps, specify a process limit of 1 in the master.cf file entry for the pprrooxxyywwrriittee service.

This request is supported in Postfix 2.5 and later.
ddeelleettee _m_a_p_t_y_p_e_:_m_a_p_n_a_m_e _f_l_a_g_s _k_e_y Delete the data stored under the requested key.
The reply is the request completion status code. The _m_a_p_t_y_p_e_:_m_a_p_n_a_m_e and _f_l_a_g_s are the same as with the ooppeenn request.

This request is supported in Postfix 2.5 and later.

The request completion status is one of OK, RETRY, NOKEY (lookup failed because the key was not found), BAD (malformed request) or DENY (the table is not approved for proxy read or update access).

There is no cclloossee command, nor are tables implicitly closed when a client disconnects. The purpose is to share tables among multiple client processes.

SERVER PROCESS MANAGEMENT



pprrooxxyymmaapp(8) servers run under control by the Postfix
mmaasstteerr(8)
server.  Each server can handle multiple simultaneous connections.
When all servers are busy while a client connects, the mmaasstteerr(8)
creates a new pprrooxxyymmaapp(8) server process, provided that the
process limit is not exceeded.
Each server terminates after serving at least $$mmaaxx__uussee clients
or after $$mmaaxx__iiddllee seconds of idle time.

SECURITY



The pprrooxxyymmaapp(8) server opens only tables that are
approved via the pprrooxxyy__rreeaadd__mmaappss or pprrooxxyy__wwrriittee__mmaappss
configuration parameters, does not talk to
users, and can run at fixed low privilege, chrooted or not.
However, running the proxymap server chrooted severely limits
usability, because it can open only chrooted tables.
        

The pprrooxxyymmaapp(8) server is not a trusted daemon process, and must not be used to look up sensitive information such as user or group IDs, mailbox file/directory names or external commands.

In Postfix version 2.2 and later, the proxymap client recognizes requests to access a table for security-sensitive purposes, and opens the table directly. This allows the same main.cf setting to be used by sensitive and non-sensitive processes.

Postfix-writable data files should be stored under a dedicated directory that is writable only by the Postfix mail system, such as the Postfix-owned ddaattaa__ddiirreeccttoorryy.

In particular, Postfix-writable files should never exist in root-owned directories. That would open up a particular type of security hole where ownership of a file or directory does not match the provider of its content.

DIAGNOSTICS

Problems and transactions are logged to ssyyssllooggdd(8).

BUGS

The pprrooxxyymmaapp(8) server provides service to multiple clients, and must therefore not be used for tables that have high-latency lookups.

The pprrooxxyymmaapp(8) read-write service does not explicitly close lookup tables (even if it did, this could not be relied on, because the process may be terminated between table updates). The read-write service should therefore not be used with tables that leave persistent storage in an inconsistent state between updates (for example, CDB). Tables that support "sync on update" should be safe (for example, Berkeley DB) as should tables that are implemented by a real DBMS.

CONFIGURATION PARAMETERS



On busy mail systems a long time may pass before
pprrooxxyymmaapp(8) relevant
changes to mmaaiinn..ccff are picked up. Use the command
"ppoossttffiixx rreellooaadd" to speed up a change.
        

The text below provides only a parameter summary. See ppoossttccoonnff(5) for more details including examples.

ccoonnffiigg__ddiirreeccttoorryy ((sseeee ''ppoossttccoonnff --dd'' oouuttppuutt)) The default location of the Postfix main.cf and master.cf
configuration files.
ddaattaa__ddiirreeccttoorryy ((sseeee ''ppoossttccoonnff --dd'' oouuttppuutt)) The directory with Postfix-writable data files (for example:
caches, pseudo-random numbers).
ddaaeemmoonn__ttiimmeeoouutt ((1188000000ss)) How much time a Postfix daemon process may take to handle a
request before it is terminated by a built-in watchdog timer.
iippcc__ttiimmeeoouutt ((33660000ss)) The time limit for sending or receiving information over an internal
communication channel.
mmaaxx__iiddllee ((110000ss)) The maximum amount of time that an idle Postfix daemon process waits
for an incoming connection before terminating voluntarily.
mmaaxx__uussee ((110000)) The maximal number of incoming connections that a Postfix daemon
process will service before terminating voluntarily.
pprroocceessss__iidd ((rreeaadd--oonnllyy)) The process ID of a Postfix command or daemon process.
pprroocceessss__nnaammee ((rreeaadd--oonnllyy)) The process name of a Postfix command or daemon process.
pprrooxxyy__rreeaadd__mmaappss ((sseeee ''ppoossttccoonnff --dd'' oouuttppuutt)) The lookup tables that the pprrooxxyymmaapp(8) server is allowed to
access for the read-only service.

Available in Postfix 2.5 and later:

ddaattaa__ddiirreeccttoorryy ((sseeee ''ppoossttccoonnff --dd'' oouuttppuutt)) The directory with Postfix-writable data files (for example:
caches, pseudo-random numbers).
pprrooxxyy__wwrriittee__mmaappss ((sseeee ''ppoossttccoonnff --dd'' oouuttppuutt)) The lookup tables that the pprrooxxyymmaapp(8) server is allowed to
access for the read-write service.

SEE ALSO


postconf(5), configuration parameters
master(5), generic daemon options

README FILES



Use "ppoossttccoonnff rreeaaddmmee__ddiirreeccttoorryy" or
"ppoossttccoonnff hhttmmll__ddiirreeccttoorryy" to locate this information.

DATABASE_README, Postfix lookup table overview

LICENSE



The Secure Mailer license must be distributed with this software.

HISTORY



The proxymap service was introduced with Postfix 2.0.

AUTHOR(S)


Wietse Venema
IBM T.J. Watson Research
P.O. Box 704
Yorktown Heights, NY 10598, USA