This appendix gives a brief description of the functions a port monitor must perform to run under the service access facility (SAF) and service access controller (SAC).
The SAF generalizes the procedures for service access so that login access on the local system and network access to local services are managed in similar ways. Under the SAF, systems may access services using a variety of port monitors, including ttymon, the listener, and port monitors written expressly for a user's application.
The manner in which a port monitor observes and manages access ports is specific to the port monitor and not to any component of the SAF. Users may therefore extend their systems by developing and installing their own port monitors. One of the important features of the SAF is that it can be extended in this way by users.
Relative to the SAF, a service is a process that is started. There are no restrictions on the functions a service may provide.
The SAF consists of a controlling process, the service access controller (SAC), and two administrative levels corresponding to two levels in the supporting directory structure. The top administrative level is concerned with port monitor administration, the lower level with service administration.
From an administrative point of view, the SAF consists of the following components:
The SAC
A per-system configuration script
The SAC administrative file
The SAC administrative command sacadm
Port monitors
Optional per-port monitor configuration scripts
An administrative file (for each port monitor)
The administrative command pmadm
Optional per-service configuration scripts
The SAC is the SAF's controlling process. The SAC is started by init() by means of an entry in /etc/inittab. Its function is to maintain the port monitors on the system in the state specified by the system administrator.
The administrative command sacadm is used to tell the SAC to change the state of a port monitor. sacadm can also be used to add or remove a port monitor from SAC supervision and to list information about port monitors known to the SAC.
The SAC's administrative file contains a unique tag for each port monitor known to the SAC and the path name of the command used to start each port monitor.
The SAC performs three main functions:
Customizes its own environment
Starts the appropriate port monitors
Polls its port monitors and initiates recovery procedures when necessary
A port monitor is a process that is responsible for monitoring a set of homogeneous, incoming ports on a machine. A port monitor's major purpose is to detect incoming service requests and to dispatch them appropriately.
A port is an externally seen access point on a system. A port may be an address on a network (TSAP or PSAP), a hardwired terminal line, an incoming phone line, etc. The definition of what constitutes a port is strictly a function of the port monitor itself.
A port monitor performs certain basic functions. Some of these are required to conform to the SAF; others may be specified by the requirements and design of the port monitor itself.
Port monitors have two main functions:
Managing ports
Monitoring ports for indications of activity
The first function of a port monitor is to manage a port. The actual details of how a port is managed are defined by the person who defines the port monitor. A port monitor is not restricted to handling a single port; it may handle multiple ports simultaneously.
Some examples of port management are setting the line speed on incoming phone connections, binding an appropriate network address, reinitializing the port when the service terminates, outputting a prompt, etc.
The second function of a port monitor is to monitor the port or ports for which it is responsible for indications of activity. Two types of activity may be detected.
The first is an indication to the port monitor to take some port monitor-specific action. Pressing the break key to indicate that the line speed should be cycled is an example of a port monitor activity. Not all port monitors need to recognize and respond to the same indications. The indication used to attract the attention of the port monitor is defined by the person who defines the port monitor.
The second is an incoming service request. When a service request is received, a port monitor must be able to determine which service is being requested from the port on which the request is received. Note that the same service may be available on more than one port.
This section briefly describes other port monitor functions.
A port monitor must be able to restrict access to the system without disturbing services that are still running. In order to do this, a port monitor must maintain two internal states: enabled and disabled. The port monitor starts in the state indicated by the ISTATE
environment variable provided by the sac. See "The SAC/Port Monitor Interface".
Enabling or disabling a port monitor affects all ports for which the port monitor is responsible. If a port monitor is responsible for a single port, only that port will be affected. If a port monitor is responsible for multiple ports, the entire collection of ports will be affected.
Enabling or disabling a port monitor is a dynamic operation: It causes the port monitor to change its internal state. The effect does not persist across new invocations of the port monitor.
Enabling or disabling an individual port, however, is a static operation: It causes a change to an administrative file. The effect of this change will persist across new invocations of the port monitor.
Port monitors are responsible for creating utmp entries with the type field set to USER_PROCESS for services they start, if this action has been specified (that is, if -fu was specified in the pmadm line that added the service). These utmp entries may in turn be modified by the service. When the service terminates, the utmp entry must be set to DEAD_PROCESS.
When a port monitor starts, it writes its process id into a file named _pid in the current directory and places an advisory lock on the file.
Before invoking the service designated in the port monitor administrative file, _pmtab, a port monitor must arrange for the per-service configuration script to be run (if one exists by calling the library function doconfig(). Because the per-service configuration script may specify the execution of restricted commands, as well as for other security reasons, port monitors are invoked with root permissions. The details of how services are invoked are specified by the person who defines the port monitor.
A port monitor must terminate itself gracefully on receipt of the signal SIGTERM. The termination sequence is the following:
The port monitor enters the stopping state; no further service requests are accepted.
Any attempt to re-enable the port monitor will be ignored.
The port monitor yields control of all ports for which it is responsible. It must be possible for a new instantiation of the port monitor to start correctly while a previous instantiation is stopping.
The advisory lock on the process id file is released. Once this lock is released, the contents of the process id file are undefined and a new invocation of the port monitor may be started.
This section briefly covers the files used by the SAF.
A port monitor's current directory contains an administrative file named _pmtab. _pmtab is maintained by the pmadm command in conjunction with a port monitor-specific administrative command.
The port monitor administrative command for a listen port monitor is nlsadmin(); the port monitor administrative command for ttymon is ttyadm(). Any port monitor written by a user must be provided with an administrative command specific to that port monitor to perform similar functions.
A port monitor's current directory also contains the per-service configuration scripts, if they exist. The names of the per-service configuration scripts correspond to the service tags in the _pmtab file.
A port monitor may create private files in the directory /var/saf/tag, where tag is the name of the port monitor. Examples of private files are log files or temporary files.
The sac creates two environment variables for each port monitor it starts:
This variable is set to a unique port monitor tag by the sac. The port monitor uses this tag to identify itself in response to sac messages. ISTATE
is used to indicate to the port monitor what its initial internal state should be. ISTATE
is set to "enabled" or "disabled" to indicate that the port monitor is to start in the enabled or disabled state respectively. The sac performs a periodic sanity poll of the port monitors.
The sac communicates with port monitors through FIFOs. A port monitor should open _pmpipe, in the current directory, to receive messages from the sac and ../_sacpipe to send return messages to the sac.
This section describes the messages that may be sent from the sac to a port monitor (sac messages), and from a port monitor to the sac (port monitor messages). These messages are sent through FIFOs and are in the form of C structures
. See Example F-2.
The format of messages from the sac is defined by the structure
sacmsg:
struct sacmsg { int sc_size; /* size of optional data portion */ char sc_type; /* type of message */ };
The sac may send four types of messages to port monitors. The type of message is indicated by setting the sc_type field of the sacmsg structure to one of the following:
SC_STATUS status request SC_ENABLE enable message SC_DISABLE disable message SC_READDB message indicating that the port monitor's _pmtab file should be read
sc_size indicates the size of the optional data part of the message. See "Message Classes". For Solaris, sc_size should always be set to 0.
A port monitor must respond to every message sent by the sac.
The format of messages from a port monitor to the sac is defined by the structure pmmsg:
struct pmmsg { char pm_type; /* type of message */ unchar pm_state; /* current state of port monitor */ char pm_maxclass; /* maximum message class this port monitor understands */ char pm_tag[PMTAGSIZE + 1]; /* port monitor's tag */ int pm_size; /* size of optional data portion */ };
Port monitors may send two types of messages to the sac. The type of message is indicated by setting the pm_type field of the pmmsg structure to one of the following:
PM_STATUS state information PM_UNKNOWN negative acknowledgment
For both types of messages, the pm_tag field is set to the port monitor's tag and the pm_state field is set to the port monitor's current state. Valid states are:
PM_STARTING starting PM_ENABLED enabled PM_DISABLED disabled PM_STOPPING stopping
The current state reflects any changes caused by the last message from the sac.
The status message is the normal return message. The negative acknowledgment should be sent only when the message received is not understood.
pm_size indicates the size of the optional data part of the message. pm_maxclass is used to specify a message class. Both are discussed under "Message Classes".". In Solaris, always set pm_maxclass to 1 and sc_size to 0.
Port monitors may never initiate messages; they may only respond to messages that they receive.
The concept of message class has been included to accommodate possible SAF extensions. The messages described above are all class 1 messages. None of these messages contains a variable data portion; all pertinent information is contained in the message header.
If new messages are added to the protocol, they will be defined as new message classes (for example, class 2). The first message the sac sends to a port monitor will always be a class 1 message. Since all port monitors, by definition, understand class 1 messages, the first message the sac sends is guaranteed to be understood. In its response to the sac, the port monitor sets the pm_maxclass field to the maximum message class number for that port monitor. The sac will not send messages to a port monitor from a class with a larger number than the value of pm_maxclass. Requests that require messages of a higher class than the port monitor can understand will fail. For Solaris, always set pm_maxclass to 1.
For any given port monitor, messages of class pm_maxclass and messages of all classes with values lower than pm_maxclass are valid. Thus, if the pm_maxclass field is set to 3, the port monitor understands messages of classes 1, 2, and 3. Port monitors may not generate messages; they may only respond to messages. A port monitor's response must be of the same class as the originating message.
Since only the sac can generate messages, this protocol will function even if the port monitor is capable of dealing with messages of a higher class than the sac can generate.
pm_size (an element of the pmmsg structure) and sc_size (an element of the sacmsg structure) indicate the size of the optional data part of the message. The format of this part of the message is undefined. Its definition is inherent in the type of message. For Solaris, always set both sc_size and pm_size to 0.
This section discusses the administrative files available under the SAC.
The service access controller's administrative file contains information about all the port monitors for which the SAC is responsible. This file exists on the delivered system. Initially, it is empty except for a single comment line that contains the version number of the SAC. Port monitors are added to the system by making entries in the SAC's administrative file. These entries should be made using the administrative command sacadm with a -a option. sacadm is also used to remove entries from the SAC's administrative file.
Each entry in the SAC's administrative file contains the following information, shown in Table F-1.
Table F-1 Service Access Controller _sactab File
Fields |
Description |
---|---|
PMTAG |
A unique tag that identifies a particular port monitor. The system administrator is responsible for naming a port monitor. This tag is then used by the SAC to identify the port monitor for all administrative purposes. PMTAG may consist of up to 14 alphanumeric characters. |
The type of the port monitor. In addition to its unique tag, each port monitor has a type designator. The type designator identifies a group of port monitors that are different invocations of the same entity. ttymon and listen are examples of valid port monitor types. The type designator is used to facilitate the administration of groups of related port monitors. Without a type designator, the system administrator has no way of knowing which port monitor tags correspond to port monitors of the same type. PMTYPE may consist of up to 14 alphanumeric characters. |
|
FLGS |
The flags that are currently defined are: -d When started, do not enable the port monitor. -x Do not start the port monitor. If no flag is specified, the default action is taken. By default a port monitor is started and enabled. |
RCNT |
The number of times a port monitor may fail before being placed in a failed state. Once a port monitor enters the failed state, the SAC will not try to restart it. If a count is not specified when the entry is created, this field is set to 0. A restart count of 0 indicates that the port monitor is not to be restarted when it fails. |
COMMAND |
A string representing the command that will start the port monitor. The first component of the string, the command itself, must be a full path name. |
Each port monitor will have two directories for its exclusive use. The current directory will contain files defined by the SAF (_pmtab, _pid) and the per-service configuration scripts, if they exist. The directory /var/saf/pmtag, where pmtag is the tag of the port monitor, is available for the port monitor's private files.
Each port monitor has its own administrative file. The pmadm command should be used to add, remove, or modify service entries in this file. Each time a change is made using pmadm, the corresponding port monitor rereads its administrative file. Each entry in a port monitor's administrative file defines how the port monitor treats a specific port and what service is to be invoked on that port.
Some fields must be present for all types of port monitors. Each entry must include a service tag to identify the service uniquely and an identity to be assigned to the service when it is started (for example, root).
The combination of a service tag and a port monitor tag uniquely define an instance of a service. The same service tag may be used to identify a service under a different port monitor. The record must also contain port monitor specific data (for example, for a ttymon port monitor, this will include the prompt string which is meaningful to ttymon). Each type of port monitor must provide a command that takes the necessary port monitor-specific data as arguments and outputs these data in a form suitable for storage in the file. The ttyadm command does this for ttymon and nlsadmin does it for listen. For a user-defined port monitor, a similar administrative command must also be supplied.
Each service entry in the port monitor administrative file must have the following format and contain the information listed below:
svctag:flgs:id:reserved:reserved:reserved:pmspecific# comment
SVCTAG is a unique tag that identifies a service. This tag is unique only for the port monitor through which the service is available. Other port monitors may offer the same or other services with the same tag. A service requires both a port monitor tag and a service tag to identify it uniquely.
SVCTAG may consist of up to 14 alphanumeric characters. The service entries are defined in Table F-2.
Table F-2 SVCTAG Service Entries
Service Entries |
Description |
---|---|
FLGS |
Flags with the following meanings may currently be included in this field: -x Do not enable this port. By default the port is enabled. -u Create a utmp entry for this service. By default no utmp entry is created for the service. |
ID |
The identity under which the service is to be started. The identity has the form of a login name as it appears in /etc/passwd. |
PMSPECIFIC |
Examples of port monitor information are addresses, the name of a process to execute, or the name of a STREAMS pipe to pass a connection through. This information will vary to meet the needs of each different type of port monitor. |
COMMENT |
Port monitors may ignore the -u flag if creating a utmp entry for the service is not appropriate to the manner in which the service is to be invoked. Some services may not start properly unless utmp entries have been created for them (for example, login).
Each port monitor administrative file must contain one special comment of the form:
# VERSION=value
where value is an integer that represents the port monitor's version number. The version number defines the format of the port monitor administrative file. This comment line is created automatically when a port monitor is added to the system. It appears on a line by itself, before the service entries.
sacadm is the administrative command for the upper level of the SAF hierarchy, that is, for port monitor administration (see the sacadm(1M) manpage). Under the SAF, port monitors are administered by using the sacadm command to make changes in the SAC's administrative file. sacadm performs the following functions:
Prints requested port monitor information from the SAC administrative file
Adds or removes a port monitor
Enables or disables a port monitor
Starts or stops a port monitor
Installs or replaces a per-system configuration script
Installs or replaces a per-port monitor configuration script
pmadm is the administrative command for the lower level of the SAF hierarchy, that is, for service administration (see the pmadm(1M) manpage). A port may have only one service associated with it although the same service may be available through more than one port. pmadm performs the following functions:
Prints service status information from the port monitor's administrative file
Adds or removes a service
Enables or disables a service
Installs or replaces a per-service configuration script
Note that in order to identify an instance of a service uniquely, the pmadm command must identify both the service (-s) and the port monitor or port monitors through which the service is available (-p or -t).
In the previous section, two pieces of information included in the _pmtab file were described: the port monitor's version number and the port monitor part of the service entries in the port monitor's _pmtab file. When a new port monitor is added, the version number must be known so that the _pmtab file can be correctly initialized. When a new service is added, the port monitor part of the _pmtab entry must be formatted correctly.
Each port monitor must have an administrative command to perform these two tasks. The person who defines the port monitor must also define such an administrative command and its input options. When the command is invoked with these options, the information required for the port monitor part of the service entry must be correctly formatted for inclusion in the port monitor's _pmtab file and must be written to the standard output. To request the version number the command must be invoked with a -V option; when it is invoked in this way, the port monitor's current version number must be written to the standard output.
If the command fails for any reason during the execution of either of these tasks, no data should be written to standard output.
The interface between a port monitor and a service is determined solely by the service. Two mechanisms for invoking a service are presented here as examples.
The first interface is for services that are started anew with each request. This interface requires the port monitor to first fork() a child process. The child will eventually become the designated service by performing an exec(). Before the exec() happens, the port monitor may take some port monitor-specific action; however, one action that must occur is the interpretation of the per-service configuration script, if one is present. This is done by calling the library routine doconfig().
The second interface is for invocations of services that are actively running. To use this interface, a service must have one end of a stream pipe open and be prepared to receive connections through it.
To implement a port monitor, several generic requirements must be met. This section summarizes these requirements. In addition to the port monitor itself, an administrative command must be supplied.
When a port monitor is started, it expects an initial execution environment in which:
It has no file descriptors open
It cannot be a process group leader
It has an entry in /etc/utmp of type LOGIN_PROCESS
An environment variable, ISTATE
, is set to "enabled" or "disabled" to indicate the port monitor's correct initial state
An environment variable, PMTAG
, is set to the port monitor's assigned tag
The directory that contains the port monitor's administrative files is its current directory
The port monitor is able to create private files in the directory /var/saf/tag, where tag is the port monitor's tag
Relative to its current directory, the following key files exist for a port monitor.
Table F-3 Key Port Monitor Files
File |
Description |
---|---|
The port monitor's configuration script. The port monitor configuration script is run by the SAC. The SAC is started by init() as a result of an entry in /etc/inittab that calls sac. |
|
The port monitor's administrative file. This file contains information about the ports and services for which the port monitor is responsible. |
|
The FIFO through which the port monitor will receive messages from sac. |
|
The per-service configuration script for the service with the tag svctag. |
|
The FIFO through which the port monitor will send messages to sac. |
A port monitor is responsible for performing the following tasks in addition to its port monitor function:
Write its process id into the file _pid and place an advisory lock on the file
Follow the protocol for message exchange with sac
A port monitor must perform the following tasks during service invocation:
Create a utmp entry if the requested service has the "-u" flag set in _pmtab
Port monitors may ignore this flag if creating a utmp entry for the service does not make sense because of the manner in which the service is to be invoked. On the other hand, some services may not start properly unless utmp entries have been created for them.
Interpret the per-service configuration script for the requested service, if it exists, by calling the doconfig() library routine
The library routine doconfig(), defined in libnsl.so, interprets the configuration scripts contained in the files /etc/saf/_sysconfig (the per-system configuration file), and /etc/saf/pmtag/_config (per-port monitor configuration files); and in /etc/saf/pmtag/svctag (per-service configuration files). Its syntax is:
# include <sac.h> int doconfig (int fd, char *script, long rflag);
script is the name of the configuration script; fd is a file descriptor that designates the stream to which stream manipulation operations are to be applied; rflag is a bitmask that indicates the mode in which script is to be interpreted. rflag may take two values, NORUN and NOASSIGN, which may be or'd. If rflag is zero, all commands in the configuration script are eligible to be interpreted. If rflag has the NOASSIGN bit set, the assign command is considered illegal and will generate an error return. If rflag has the NORUN bit set, the run and runwait commands are considered illegal and will generate error returns.
If a command in the script fails, the interpretation of the script ceases at that point and a positive integer is returned; this number indicates which line in the script failed. If a system error occurs, a value of -1 is returned.
If a script fails, the process whose environment was being established should not be started.
In the example, doconfig() is used to interpret a per-service configuration script.
. . . if ((i = doconfig (fd, svctag, 0)) != 0){ error ("doconfig failed online %d of script %s",i,svctag); }
The per-system configuration file, /etc/saf/_sysconfig, is delivered empty. It may be used to customize the environment for all services on the system by writing a command script in the interpreted language described in this chapter and on the doconfig(3N)manpage. When the SAC is started, it calls the doconfig() function to interpret the per-system configuration script. The SAC is started when the system enters multiuser mode.
Per-port monitor configuration scripts (/etc/saf/pmtag/_config) are optional. They allow the user to customize the environment for any given port monitor and for the services that are available through the ports for which that port monitor is responsible. Per-port monitor configuration scripts are written in the same language used for per-system configuration scripts.
The per-port monitor configuration script is interpreted when the port monitor is started. The port monitor is started by the SAC after the SAC has itself been started and after it has run its own configuration script, /etc/saf/_sysconfig.
The per-port monitor configuration script may override defaults provided by the per-system configuration script.
Per-service configuration files allow the user to customize the environment for a specific service. For example, a service may require special privileges that are not available to the general user. Using the language described in the doconfig(3N)manpage, you can write a script that will grant or limit such special privileges to a particular service offered through a particular port monitor.
The per-service configuration may override defaults provided by higher-level configuration scripts. For example, the per-service configuration script may specify a set of STREAMS modules other than the default set.
The language in which configuration scripts are written consists of a sequence of commands, each of which is interpreted separately. The following reserved keywords are defined: assign, push, pop, runwait, and run. The comment character is #. Blank lines are not significant. No line in a command script may exceed 1024 characters.
assign variable=value
Used to define environment variables. variable is the name of the environment variable and value is the value to be assigned to it. The value assigned must be a string constant; no form of parameter substitution is available. value may be quoted. The quoting rules are those used by the shell for defining environment variables. assign will fail if space cannot be allocated for the new variable or if any part of the specification is invalid.
push module1[, module2, module3, ...]
Used to push STREAMS modules onto the stream designated by fd. See the doconfig(3N)manpage. module1 is the name of the first module to be pushed, module2 is the name of the second module to be pushed, and so on. The command will fail if any of the named modules cannot be pushed. If a module cannot be pushed, the subsequent modules on the same command line will be ignored and modules that have already been pushed will be popped.
pop [module]
Used to pop STREAMS modules off the designated stream. If pop is invoked with no arguments, the top module on the stream is popped. If an argument is given, modules will be popped one at a time until the named module is at the top of the stream. If the named module is not on the designated stream, the stream is left as it was and the command fails. If module is the special keyword ALL, then all modules on the stream will be popped. Note that only modules above the topmost driver are affected.
runwait command
The runwait command runs a command and waits for it to complete. command is the path name of the command to be run. The command is run with /bin/sh -c prepended to it; shell scripts may thus be executed from configuration scripts. The runwait command will fail if command cannot be found or cannot be executed, or if command exits with a nonzero status.
run command
The run command is identical to runwait except that it does not wait for command to complete. command is the path name of the command to be run. run will not fail unless it is unable to create a child process to execute the command.
Although they are syntactically indistinguishable, some of the commands available to run and runwait are interpreter built-in commands. Interpreter built-ins are used when it is necessary to alter the state of a process within the context of that process. The doconfig() interpreter built-in commands are similar to the shell special commands and, like these, they do not spawn another process for execution. See the sh(1)manpage. The initial set of built-in commands is:
cd ulimit umask
This section describes the form of the SAC and port monitor administrative commands used to install the three types of configuration scripts. Per-system and per-port monitor configuration scripts are administered using the sacadm command. Per-service configuration scripts are administered using the pmadm command.
sacadm -G [ -z script ]
The -G option is used to print or replace the per-system configuration script. The -G option by itself prints the per-system configuration script. The -G option in combination with a -z option replaces /etc/saf/_sysconfig with the contents of the file script. Other combinations of options with a -G option are invalid.
The _sysconfig file in the example sets the time zone variable, TZ.
assign TZ=EST5EDT # set TZ runwait echo SAC is starting > /dev/console
sacadm -g -p pmtag [ -z script ]
The -g option is used to print, install, or replace the per-port monitor configuration script. A -g option requires a -p option. The -g option with only a -p option prints the per-port monitor configuration script for port monitor pmtag. The -g option with a -p option and a -z option installs the file script as the per-port monitor configuration script for port monitor pmtag, or, if /etc/saf/pmtag/_config exists, it replaces _config with the contents of script. Other combinations of options with -g are invalid.
In the hypothetical _config file in the figure, the command /usr/bin/daemon is assumed to start a daemon process that builds and holds together a STREAMS multiplexor. By installing this configuration script, the command can be executed just before starting the port monitor that requires it.
# build a STREAMS multiplexor run /usr/bin/daemon runwait echo $PMTAG is starting > /dev/console
pmadm -g -p pmtag -s svctag [ -z script ] pmadm -g -s svctag -t type -z script
Per-service configuration scripts are interpreted by the port monitor before the service is invoked.
The SAC interprets both its own configuration file, _sysconfig, and the port monitor configuration files. Only the per-service configuration files are interpreted by the port monitors.
The -g option is used to print, install, or replace a per-service configuration script. The -g option with a -p option and a -s option prints the per-service configuration script for service svctag available through port monitor pmtag. The -g option with a -p option, a -s option, and a -z option installs the per-service configuration script contained in the file script as the per-service configuration script for service svctag available through port monitor pmtag. The -g option with a -s option, a -t option, and a -z option installs the file script as the per-service configuration script for service svctag available through any port monitor of type type. Other combinations of options with -g are invalid.
The following per-service configuration script does two things: It specifies the maximum file size for files created by a process by setting the process's ulimit to 4096. It also specifies the protection mask to be applied to files created by the process by setting umask to 077.
runwait ulimit 4096 runwait umask 077
Example F-1shows an example of a "null" port monitor that simply responds to messages from the SAC.
Example F-2 shows the sac.h header file.
Figure F-2 is a logical diagram of the SAF. It illustrates how a single service access controller may spawn a number of port monitors on a per-system basis. This means that several monitors may be running concurrently, providing for the simultaneous operation of several different protocols.
"/etc/saf/_sysconfig " is the corresponding directory structure diagram. Following the diagram is a description of the files and directories..
The per-system configuration script.
The SAC's administrative file. Contains information about the port monitors for which the SAC is responsible.
The home directory for port monitor pmtag.
The per-port monitor configuration script for port monitor pmtag.
Port monitor pmtag's administrative file. Contains information about the services for which pmtag is responsible.
The file in which the per-service configuration script for service svctag (available through port monitor pmtag) is placed.
The file in which a port monitor writes its process id in the current directory and places an advisory lock on the file.
The file in which the port monitor receives messages from the sac and ../_sacpipe and sends return messages to the sac.
The SAC's log file.
The directory for files created by port monitor pmtag, for example its log file.