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Appendix A Inetd.conf Format

This appendix describes the format of inetd compatible configuration files. See inetd, for the discussion on how to use such files with GNU pies.

The inetd configuration file has line oriented format. Comments are denoted by a ‘#’ at the beginning of a line. Empty lines and comments are ignored. Each non-empty line must be either a service definition, or address specification.

Service definition consists of at least 6 fields separated by any amount of the white space. These fields are described in the following table (optional parts are enclosed in square brackets):

[service-node:]service-name

The service-name entry is the name of a valid service in the file /etc/services. For built-in services (see builtin), the service name must be the official name of the service (that is, the first entry in /etc/services), or a numeric representation thereof. For TCPMUX services, the value of the ‘service name’ field consists of the string ‘tcpmux’ followed by a slash and the locally-chosen service name (see TCPMUX). Optionally, a plus sign may be inserted after the slash, indicating that pies must issue a ‘+’ response before starting this server.

The ‘service-name’ part corresponds to component tag in pies.conf (see Component Statement). For built-in components, it corresponds to the service statement (see service).

Optional ‘service-node’ prefix is allowed for internet services. When present, it supplies the local addresses inetd should listen on for that service. ‘Service-node’ consists of a comma-separated list of addresses. Both symbolic host names and numeric IP addresses are allowed. Symbolic hostnames are looked up in DNS service. If a hostname has multiple address mappings, a socket is created to listen on each address. A special hostname ‘*’ stands for INADDR_ANY.

socket type

The socket type should be one of ‘stream’, ‘dgram’, ‘raw’, ‘rdm’, or ‘seqpacket’. TCPMUX services must use ‘stream’.

This field corresponds to the socket-type statement in pies.conf. See socket-type.

protocol

The protocol must be a valid protocol as given in /etc/protocols. Examples might be ‘tcp’ or ‘udp’. TCPMUX services must use ‘tcp’.

The ‘service-node’ prefix and ‘socket-type’ field correspond to the socket statement in pies.conf. See inetd-socket.

For example, the following line:

10.0.0.1:ftp dgram   udp     wait    root  ftpd

is equivalent to

  socket inet+udp://10.0.0.1:ftp;
  socket-typle dgram;
wait/nowait[.max-rate]

The ‘wait/nowait’ entry specifies whether the invoked component will take over the socket associated with the service access point, and thus whether pies should wait for the server to exit before listening for new service requests. Datagram servers must use ‘wait’, as they are always invoked with the original datagram socket bound to the specified service address. These servers must read at least one datagram from the socket before exiting. If a datagram server connects to its peer, freeing the socket so that pies can go on receiving further messages from the socket, it is said to be a multi-threaded server; it should read one datagram from the socket and create a new socket connected to the peer. It should fork, and the parent should then exit to allow pies to check for new service requests to spawn new servers. Datagram servers which process all incoming datagrams on a socket and eventually time out are said to be single-threaded. Examples of such servers are comsat and talkd. tftpd is an example of a multi-threaded datagram server.

Servers using stream sockets generally are multi-threaded and use the ‘nowait’ entry. Connection requests for these services are accepted by pies, and the server is given only the newly-accepted socket connected to a client of the service. Most stream-based services and all TCPMUX services operate in this manner. For such services, the invocation rate may be limited by specifying optional ‘max-rate’ suffix (a decimal number), e.g.: ‘nowait.15’.

Stream-based servers that use ‘wait’ are started with the listening service socket, and must accept at least one connection request before exiting. Such a server would normally accept and process incoming connection requests until a timeout. Datagram services must use ‘nowait’. The only stream server marked as ‘wait’ is identd (see identd in identd manual).

The ‘wait’ field corresponds to flags wait in the pies.conf file. The ‘nowait’ corresponds to flags nowait. See flags.

The ‘max-rate’ suffix corresponds to the max-rate statement. See max-rate.

user

The user entry contains the name of the user as whom the component should run. This allows for components to be given less permission than root.

This corresponds to the user statement in pies.conf. See user.

program

The program entry contains the full file name of the program which is to be executed by pies when a request arrives on its socket. For built-in services, this entry should be ‘internal’.

It is common usage to specify /usr/sbin/tcpd in this field.

This field corresponds to the program statement in pies.conf. See program.

server program arguments

The server program arguments should be just as arguments normally are, starting with argv[0], which is the name of the program. For built-in services, this entry must contain the word ‘internal’, or be empty.

This corresponds to the command statement. See command.

Address specification is a special statement that declares the ‘service-node’ part (see above) for all the services declared below it. It consists of a host address specifier followed by a colon on a single line, e.g.:

127.0.0.1,192.168.0.5:

The address specifier from such a line is remembered and used for all further lines lacking an explicit host specifier. It remains in effect until another address specification or end of the configuration is encountered, whichever occurs first.

The following address specification:

*:

causes any previous default address specifier to be forgotten.

An example of inetd.conf file with various services follows:

ftp            stream  tcp nowait root  /usr/libexec/ftpd    ftpd -l
ntalk          dgram   udp wait   root  /usr/libexec/ntalkd  ntalkd
tcpmux         stream  tcp nowait root  internal
tcpmux/+scp-to stream  tcp nowait guest /usr/sbin/in.wydawca wydawca
tcpmux/docref  stream  tcp nowait guest /usr/bin/docref      docref

GNU Pies Manual (split by chapter):   Section:   Chapter:FastBack: Reporting Bugs   Up: Top   FastForward: User-Group ACLs   Contents: Table of ContentsIndex: Concept Index