illumos: manual page: inetd.8

INETD(8) Maintenance Commands and Procedures INETD(8)

NAME

inetd - Service Management Facility delegated restarter for inet services

SYNOPSIS

inetd [configuration-file] start | stop | refresh

svc:/network/inetd:default

DESCRIPTION

inetd is the delegated restarter for internet services for the Service
Management Facility (SMF). Its basic responsibilities are to manage
service states in response to administrative requests, system failures,
and service failures; and, when appropriate, to listen for network
requests for services.

Services are no longer managed by editing the inetd configuration file,
inetd.conf(5). Instead, you use inetconv(8) to convert the configuration
file content into SMF format services, then manage these services using
inetadm(8) and svcadm(8). Once a service has been converted by inetconv,
any changes to the legacy data in the inetd config file will not become
effective. However, inetd does alert the administrator when it notices
change in the configuration file. See the start description under the
"inetd Methods" section for further information.

Also note that the current inetd cannot be run from outside the SMF. This
means it cannot be run from the command line, as was supported by the
previous inetd. If you attempt to do this, a message is sent to stderr
displaying mappings between the options supported by the previous inetd
to the SMF version of inetd.

inetd listens for connections on behalf of all services that are in
either the online or degraded state. A service enters one of these states
when the service is enabled by the user and inetd manages to listen on
its behalf. A listen attempt can fail if another server (whether
standalone or a third-party internet service) is already listening on the
same port. When this occurs, inetd logs this condition and continues
trying to bind to the port at configured intervals a configured number of
times. See the property bind_fail_max under "Service Properties," below,
for more details.

The configuration of all inetd's managed SMF services is read when it is
started. It is reread when inetd is refreshed, which occurs in response
to an SMF request, or when it receives a SIGHUP signal. See the refresh
description under "inetd Methods" for the behavior on configuration
refresh.

You can use the inetadm(8) or svccfg(8) utilities to make configuration
changes to Internet services within the SMF repository. inetadm has the
advantage over svccfg in that it provides an Internet/RPC service
context.

Service States

As part of its service management duties, inetd implements a state
machine for each of its managed services. The states in this machine are
made up of the smf(7) set of states. The semantics of these states are as
follows:

uninitialized

inetd has yet to process this service.

online

The service is handling new network requests and might have existing
connections active.

degraded

The service has entered this state because it was able to listen and
process requests for some, but not all, of the protocols specified
for the service, having exhausted its listen retries. Existing
network connections might be active.

offline

Connections might be active, but no new requests are being handled.
This is a transient state. A service might be offline for any of the
following reasons:

o The service's dependencies are unmet. When its
dependencies become met the service's state will be re-
evaluated.

o The service has exceeded its configured connection rate
limit, max_con_rate. The service's state is re-evaluated
when its connection offline timer, con_rate_offline,
expires.

o The service has reached its allowed number of active
connections, max_copies. The service's state is re-
evaluated when the number of active connections drops
below max_copies.

o inetd failed to listen on behalf of the service on all its
protocols. As mentioned above, inetd retries up to a
configured maximum number of times, at configured
intervals.The service's state is re-evaluated when either
a listen attempt is successful or the retry limit is
reached.

disabled

The service has been turned off by an administrator, is not accepting
new connections, and has none active. Administrator intervention is
required to exit this state.

maintenance

A service is in this state because it is either malfunctioning and
needs administrator attention or because an administrator has
requested it.

Events constituting malfunctioning include: inetd's inability to
listen on behalf on any of the service's protocols before exceeding
the service's bind retry limit, non-start methods returning with non-
success return values, and the service exceeding its failure rate.

You request the maintenance state to perform maintenance on the
service, such as applying a patch. No new requests are handled in
this state, but existing connections might be active. Administrator
intervention is required to exit this state.

Use inetadm(8) to obtain the current state of a managed service.

Service Methods

As part of certain state transitions inetd will execute, if supplied, one
of a set of methods provided by the service. The set of supported methods
are:

inetd_start

Executed to handle a request for an online or degraded service.
Since there is no separate state to distinguish a service with active
connections, this method is not executed as part of a state
transition.

inetd_offline

Executed when a service is taken from the online or degraded state to
the offline state. For a wait-type service that at the time of
execution is performing its own listening, this method should result
in it ceasing listening. This method will be executed before the
disable method in the case an online/degraded service is disabled.
This method is required to be implemented for a wait-type service.

inetd_online

Executed when a service transitions from the offline state to the
online state. This method allows a service author to carry out some
preparation prior to a service starting to handle requests.

inetd_disable

Executed when a service transitions from the offline state to the
disabled state. It should result in any active connections for a
service being terminated.

inetd_refresh

Executed when both of the following conditions are met:

o inetd is refreshed, by means of the framework or a SIGHUP,
or a request comes in to refresh the service, and

o the service is currently in the online state and there are
no configuration changes that would result in the service
needing to be taken offline and brought back again.

The only compulsory method is the inetd_start method. In the absence of
any of the others, inetd runs no method but behaves as if one was run
successfully.

Service Properties

Configuration for SMF-managed services is stored in the SMF repository.
The configuration is made up of the basic configuration of a service, the
configuration for each of the service's methods, and the default
configuration applicable to all inetd-managed services.

For details on viewing and modifying the configuration of a service and
the defaults, refer to inetadm(8).

The basic configuration of a service is stored in a property group named
inetd in the service. The properties comprising the basic configuration
are as follows:

bind_addr

The address of the network interface to which the service should be
bound. An empty string value causes the service to accept connections
on any network interface.

bind_fail_interval

The time interval in seconds between a failed bind attempt and a
retry. The values 0 and -1 specify that no retries are attempted and
the first failure is handled the same as exceeding bind_fail_max.

bind_fail_max

The maximum number of times inetd retries binding to a service's
associated port before giving up. The value -1 specifies that no
retry limit is imposed. If none of the service's protocols were bound
to before any imposed limit is reached, the service goes to the
maintenance state; otherwise, if not all of the protocols were bound
to, the service goes to the degraded state.

con_rate_offline

The time in seconds a service will remain offline if it exceeds its
configured maximum connection rate, max_con_rate. The values 0 and -1
specify that connection rate limiting is disabled.

connection_backlog

The backlog queue size. Represents a limit on the number of incoming
client requests that can be queued at the listening endpoints for
servers.

endpoint_type

The type of the socket used by the service or the value tli to
signify a TLI-based service. Valid socket type values are: stream,
dgram, raw, seqpacket.

failrate_cnt

The count portion of the service's failure rate limit. The failure
rate limit applies to wait-type services and is reached when count
instances of the service are started within a given time. Exceeding
the rate results in the service being transitioned to the maintenance
state. This is different from the behavior of the previous inetd,
which continued to retry every 10 minutes, indefinitely. The
failrate_cnt check accounts for badly behaving servers that fail
before consuming the service request and which would otherwise be
continually restarted, taxing system resources. Failure rate is
equivalent to the -r option of the previous inetd. The values 0 and
-1 specify that this feature is disabled.

failrate_interval

The time portion in seconds of the service's failure rate. The values
0 and -1 specify that the failure rate limit feature is disabled.

inherit_env

If true, pass inetd's environment on to the service's start method.
Regardless of this setting, inetd will set the variables SMF_FMRI,
SMF_METHOD, and SMF_RESTARTER in the start method's environment, as
well as any environment variables set in the method context. These
variables are described in smf_method(7).

isrpc

If true, this is an RPC service.

max_con_rate

The maximum allowed connection rate, in connections per second, for a
nowait-type service. The values 0 and -1 specify that that connection
rate limiting is disabled.

max_copies

The maximum number of copies of a nowait service that can run
concurrently. The values 0 and -1 specify that copies limiting is
disabled.

name

Can be set to one of the following values:

o a service name understood by getservbyname(3SOCKET);

o if isrpc is set to true, a service name understood by
getrpcbyname(3NSL);

o if isrpc is set to true, a valid RPC program number.

proto

In the case of socket-based services, this is a list of protocols
supported by the service. Valid protocols are: tcp, tcp6, tcp6only,
udp, udp6, and udp6only. In the case of TLI services, this is a list
of netids recognized by getnetconfigent(3NSL) supported by the
service, plus the values tcp6only and udp6only. RPC/TLI services also
support nettypes in this list, and inetd first tries to interpret the
list member as a nettype for these service types. The values tcp6only
and udp6only are new to inetd; these values request that inetd listen
only for and pass on true IPv6 requests (not IPv4 mapped ones). See
"Configuring Protocols for Sockets-Based Services," below.

rpc_low_version

Lowest supported RPC version. Required when isrpc is set to true.

rpc_high_version

Highest supported RPC version. Required when isrpc is set to true.

tcp_trace

If true, and this is a nowait-type service, inetd logs the client's
IP address and TCP port number, along with the name of the service,
for each incoming connection, using the syslog(3C) facility. inetd
uses the syslog facility code daemon and notice priority level. See
syslog.conf(5) for a description of syslog codes and severity levels.
This logging is separate from the logging done by the TCP wrappers
facility.

tcp_trace is equivalent to the previous inetd's -t option (and the
/etc/default/inetd property ENABLE_CONNECTION_LOGGING).

tcp_wrappers

If true, enable TCP wrappers access control. This applies only to
services with endpoint_type set to streams and wait set to false. The
syslog facility code daemon is used to log allowed connections (using
the notice severity level) and denied traffic (using the warning
severity level). See syslog.conf(5) for a description of syslog codes
and severity levels. The stability level of the TCP wrappers facility
and its configuration files is External. As the TCP wrappers facility
is not controlled by Sun, intra-release incompatibilities are not
uncommon. See attributes(7).

For more information about configuring TCP wrappers, refer to tcpd(8)
and hosts_access(5).

tcp_wrappers is equivalent to the previous inetd's /etc/default/inetd
property ENABLE_TCPWRAPPERS.

wait

If true this is a wait-type service, otherwise it is a nowait-type
service. A wait-type service has the following characteristics:

o Its inetd_start method will take over listening duties on
the service's bound endpoint when it is executed.

o inetd will wait for it to exit after it is executed before
it resumes listening duties.
Datagram servers must be configured as being of type wait, as they
are always invoked with the original datagram endpoint that will
participate in delivering the service bound to the specified service.
They do not have separate "listening" and "accepting" sockets.
Connection-oriented services, such as TCP stream services can be
designed to be either of type wait or nowait.

A number of the basic properties are optional for a service. In their
absence, their values are taken from the set of default values present in
the defaults property group in the inetd service. These properties, with
their seed values, are listed below. Note that these values are
configurable through inetadm(8).

bind_fail_interval -1
bind_fail_max -1
con_rate_offline -1
connection_backlog 10
failrate_count 40
failrate_time 60
inherit_env true
max_con_rate -1
max_copies -1
tcp_trace false
tcp_wrappers false

Each method specified for a service will have its configuration stored in
the SMF repository, within a property group of the same name as the
method. The set of properties allowable for these methods includes those
specified for the services managed by svc.startd(8). (See svc.startd(8)
for further details.) Additionally, for the inetd_start method, you can
set the arg0 property.

The arg0 property allows external wrapper programs to be used with inetd
services. Specifically, it allows the first argument, argv[0], of the
service's start method to be something other than the path of the server
program.

In the case where you want to use an external wrapper program and pass
arguments to the service's daemon, the arguments should be incorporated
as arguments to the wrapper program in the exec property. For example:

exec='/path/to/wrapper/prog service_daemon_args'
arg0='/path/to/service/daemon'

In addition to the special method tokens mentioned in smf_method(7),
inetd also supports the :kill_process token for wait-type services. This
results in behavior identical to that if the :kill token were supplied,
except that the kill signal is sent only to the parent process of the
wait-type service's start method, not to all members of its encompassing
process contract (see process(5)).

Configuring Protocols for Sockets-Based Services
When configuring inetd for a sockets-based service, you have the choice,
depending on what is supported by the service, of the alternatives
described under the proto property, above. The following are guidelines
for which proto values to use:

o For a service that supports only IPv4: tcp and udp

o For a service that supports only IPv6: tcp6only and udp6only

o For a service that supports both IPv4 and IPv6:

o Obsolete and not recommended: tcp6 and udp6

o Recommended: use two separate entries that differ only in
the proto field. One entry has tcp and the other has
tcp6only, or udp plus udp6only.

See EXAMPLES for an example of a configuration of a service that supports
both IPv4 and IPv6.

inetd Methods
inetd provides the methods listed below for consumption by the master
restarter, svc.startd(8).

start

Causes inetd to start providing service. This results in inetd
beginning to handle smf requests for its managed services and network
requests for those services that are in either the online or degraded
state.

In addition, inetd also checks if the inetd.conf(5)-format
configuration file it is monitoring has changed since the last
inetconv(8) conversion was carried out. If it has, then a message
telling the administrator to re-run inetconv to effect the changes
made is logged in syslog.

stop

Causes inetd to stop providing service. At this point, inetd
transitions each of its services that are not in either the
maintenance or disabled states to the offline state, running any
appropriate methods in the process.

refresh

Results in a refresh being performed for each of its managed services
and the inetd.conf(5) format configuration file being checked for
change, as in the start method. When a service is refreshed, its
behavior depends on its current state:

o if it is in the maintenance or disabled states, no action
is performed because the configuration will be read and
consumed when the service leaves the state;

o if it is in the offline state, the configuration will be
read and any changes consumed immediately;

o if it is in the online or degraded state and the
configuration has changed such that a re-binding is
necessary to conform to it, then the service will be
transitioned to the offline state and back again, using
the new configuration for the bind;

o if it is in the online state and a re-binding is not
necessary, then the inetd_refresh method of the service,
if provided, will be run to allow online wait-type
services to consume any other changes.

OPTIONS

No options are supported.

OPERANDS

configuration-file

Specifies an alternate location for the legacy service file
(inetd.conf(5)).

start|stop|refresh

Specifies which of inetd's methods should be run.

EXAMPLES

Example 1: Configuring a Service that Supports Both IPv4 and IPv6

The following commands illustrate the existence of services that support
both IPv4 and IPv6 and assign proto properties to those services.

example# svcs -a | grep mysvc
online 15:48:29 svc:/network/mysvc:dgram4
online 15:48:29 svc:/network/mysvc:dgram6
online 15:51:47 svc:/network/mysvc:stream4
online 15:52:10 svc:/network/mysvc:stream6

# inetadm -M network/rpc/mysvc:dgram4 proto=udp
# inetadm -M network/rpc/mysvc:dgram6 proto=udp6only
# inetadm -M network/rpc/mysvc:stream4 proto=tcp
# inetadm -M network/rpc/mysvc:stream6 proto=tcp6only

See svcs(1) and inetadm(8) for descriptions of those commands.

ATTRIBUTES

NOTES

The inetd daemon performs the same function as, but is implemented
significantly differently from, the daemon of the same name in Solaris 9
and prior Solaris operating system releases. In the current Solaris
release, inetd is part of the Service Management Facility (see smf(7))
and will run only within that facility.

The /etc/default/inetd file has been deprecated. The functionality
represented by the properties ENABLE_CONNECTION_LOGGING and
ENABLE_TCP_WRAPPERS are now available as the tcp_trace and tcp_wrappers
properties, respectively. These properties are described above, under
"Service Properties".

May 13, 2017 INETD(8)