TCPD(1M)																  TCPD(1M)

NAME

       tcpd - access control facility for internet services

DESCRIPTION

       The  tcpd  program can be set up to monitor incoming requests for telnet, finger, ftp, exec, rsh, rlogin, tftp, talk, comsat and other ser-
       vices that have a one-to-one mapping onto executable files.

       The program supports both 4.3BSD-style sockets and System V.4-style TLI.  Functionality may be limited when the protocol underneath TLI	is
       not an internet protocol.

       Operation  is  as follows: whenever a request for service arrives, the inetd daemon is tricked into running the tcpd program instead of the
       desired server. tcpd logs the request and does some additional checks. When all is well, tcpd runs the appropriate server program and  goes
       away.

       Optional  features are: pattern-based access control, client username lookups with the RFC 931 etc. protocol, protection against hosts that
       pretend to have someone elses host name, and protection against hosts that pretend to have someone elses network address.

LIBWRAP INTERFACE

       The same monitoring and access control functionality provided by the tcpd standalone program is also available through the  libwrap  shared
       library	interface.  Some  programs,  including	the Solaris inetd daemon, have been modified  to use the libwrap interface and thus do not
       require replacing the real server programs with tcpd. The libwrap interface is also more efficient and can be used for inetd internal  ser-
       vices. See inetd(1M) for more information.

LOGGING

       Connections that are monitored by tcpd are reported through the syslog(3) facility. Each record contains a time stamp, the client host name
       and the name of the requested service.  The information can be useful to detect unwanted activities, especially	when  logfile  information
       from several hosts is merged.

       In order to find out where your logs are going, examine the syslog configuration file, usually /etc/syslog.conf.

ACCESS CONTROL

       Optionally,  tcpd  supports  a simple form of access control that is based on pattern matching.	The access-control software provides hooks
       for the execution of shell commands when a pattern fires.  For details, see the hosts_access(4) manual page.

HOST NAME VERIFICATION

       The authentication scheme of some protocols (rlogin, rsh) relies on host names. Some implementations believe the host name  that  they  get
       from any random name server; other implementations are more careful but use a flawed algorithm.

       tcpd  verifies  the  client  host  name	that  is returned by the address->name DNS server by looking at the host name and address that are
       returned by the name->address DNS server.  If any discrepancy is detected, tcpd concludes that it is dealing with a host that  pretends	to
       have someone elses host name.

       If  the	sources are compiled with -DPARANOID, tcpd will drop the connection in case of a host name/address mismatch.  Otherwise, the host-
       name can be matched with the PARANOID wildcard, after which suitable action can be taken.

HOST ADDRESS SPOOFING

       Optionally, tcpd disables source-routing socket options on every connection that it deals with. This will take care of  most  attacks  from
       hosts that pretend to have an address that belongs to someone elses network. UDP services do not benefit from this protection. This feature
       must be turned on at compile time.

RFC 931
       When RFC 931 etc. lookups are enabled (compile-time option) tcpd will attempt to establish the name of the client user. This  will  succeed
       only  if  the  client host runs an RFC 931-compliant daemon.  Client user name lookups will not work for datagram-oriented connections, and
       may cause noticeable delays in the case of connections from PCs.

       Warning: If the local system runs an RFC 931 server it is important that it be configured NOT to use TCP Wrappers, or that TCP Wrappers	be
       configured  to  avoid  RFC 931-based access control for this service.  If you use usernames in the access control files, make sure that you
       have a hosts.allow entry that allows the RFC 931 service (often called "identd" or "auth") without any username	restrictions.  Failure	to
       heed this warning can result in two hosts getting in an endless loop of consulting each other's identd services.

EXAMPLES

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +--------------------+-----------------+
       |  ATTRIBUTE TYPE    | ATTRIBUTE VALUE |
       +--------------------+-----------------+
       |Availability	    | SUNWtcpd	      |
       +--------------------+-----------------+
       |Interface Stability | Committed       |
       +--------------------+-----------------+
NOTES

       Source for tcp_wrappers is available in the SUNWtcpdS package.

																	  TCPD(1M)