July 12, 1996
hfaxd - HylaFAX client-server protocol server
/usr/sbin/hfaxd [ -d ] [ -q dir ] [ -o port ] [ -O ] [ -l bindaddress ] [ -i port ] [ -I ] [ -s port ] [ -S ]
hfaxd is the HylaFAX program that implements the server portion of:
Additional client-server protocols are planned and hfaxd is intended to be the ‘‘carrier’’ through which they are supported.
|o||the client-server protocol and|
|o||the Simple Network Paging Protocol (SNPP) used to submit message pager jobs to the IXO/TAP and UCP support.|
hfaxd is typically used in one of two ways; either as a standalone process that is started at system boot time to listen for client connections on one or more ports (in which case the -i, -o, or -s option must be used), or as a subservient process to the inetd(8) program. The two forms of use may however be combined so long as the same service is not provided both by the standalone hfaxd and through inetd.
HYLAFAX (NEW) CLIENT-SERVER PROTOCOL SUPPORT
If hfaxd is started with the -i option it will service clients using the HylaFAX client-server protocol. This protocol is strongly related to the Internet File Transfer Protocol (FTP); so much so in fact that FTP client programs that include support for ‘‘quoted commands’’ may be used to communicate with hfaxd using the new protocol. (It should also be possible to use FTP-aware World Wide Web browsers such as Mosaic and Netscape Navigator to access HylaFAX servers through the new protocol; but the current format for information returned in directory listings confuses them.)
The hfaxd server currently recognizes the following protocol requests; case is not distinguished. Entries marked with a \(S1 can be used only when the client has established administrative privileges with ADMIN.
Request Description ABOR abort previous command ACCT specify account (ignored) ADMIN specify password for administrative privileges ALLO allocate storage (vacuously) ANSWER\(S1 request that call be answered APPE append to a file CDUP change to parent of current working directory CHMOD change mode of a file CHOWN\(S1 change owner of a file CWD change working directory DELE delete a file DISABLE\(S1 disable outbound use of modem ENABLE\(S1 enable outbound use of modem HELP give help information FILEFMT specify/query format for returning file status FILESORTFMT specify/query format for sorting file status listing FORM specify data transfer format IDLE set idle-timer (in seconds) JDELE delete done or suspended job JINTR interrupt job JKILL kill job JNEW create new job JOB set/query current job JOBFMT specify/query format for returning job status JOBSORTFMT specify/query format for sorting job status listing JPARM specify/query job state parameter JREST reset current job state JSUBM submit job to scheduler JSUSP suspend job from scheduling JWAIT wait for job to complete JGDELE delete group of jobs JGKILL kill group of jobs JGINTR interrupt group of jobs JGNEW place current job in a new job group JGPARM set state parameter in a group of jobs JGREST reset current state for a group of jobs JGRP set/query current job group JGSUBM submit group of jobs to scheduler JGSUSP suspend group of jobs from scheduling JGWAIT wait for group of jobs to complete LIST list files in a directory MDTM show last modification time of file MODE specify data transfer mode MDMFMT specify/query format for returning modem status MDMSORTFMT specify/query format for sorting modem status listing NLST give name list of files in directory NOOP do nothing PASS specify password PASV prepare for server-to-server transfer PORT specify data connection port PWD print the current working directory QUIT terminate session RCVFMT specify/query format for returning received facsimile status RCVSORTFMT specify/query format for sorting received facsimile status listing REIN reinitiate server state REST restart incomplete transfer RETP retrieve the next page in a file RETR retrieve a file SHUT schedule server shutdown SITE non-standard commands (see next section) SIZE return size of file STAT return status of server or file STOR store a file STOT store a temporary file with a unique name STOU store a file with a unique name STRU specify data transfer structure SYST show operating system type of server system TYPE specify data transfer type TZONE specify timezone handling for dates and times USER specify user name VRFY verify dialstring handling and/or least-cost routing
The following non-standard or experimental commands are supported through the SITE request.
Request Description ADDMODEM\(S1 add/configure new modem for use ADDUSER\(S1 add client access control entry CONFIG\(S1 send configuration parameter setting to server DELMODEM\(S1 deconfigure/remove modem DELUSER\(S1 remove client access control entry TRIGGER register realtime event trigger HELP give help information, e.g., SITE HELP
In addition FTP requests that are specified in Internet RFC 959 but not listed here are recognized, but not implemented.
The hfaxd server will abort an active data transfer only when the ABOR command is preceded by a Telnet "Interrupt Process" (IP) signal and a Telnet "Synch" signal in the command Telnet stream, as described in Internet RFC 959. If a STAT command is received during a data transfer, preceded by a Telnet IP and Synch, transfer status will be returned.
SIMPLE NETWORK PAGING PROTOCOL (SNPP) SUPPORT
If hfaxd is started with the -s option it will service clients using the Simple Network Pager Protocol (SNPP) as specified in RFC 1861 (which obsoletes RFC 1645).
The hfaxd server currently recognizes the SNPP protocol requests listed below. Requests marked with a \(S1 are non-standard extensions to RFC 1861 that may be added to SNPP at some future time. Case is not distinguished and only the first four characters of requests are used in identifying commands.
Request Description 2WAY preface a 2-way transaction ABOR\(S1 abort previous command ACKR set read acknowledgement handling for subsequent requests ALER set the alter-level for subsequent requests CALL set the caller-ID for subsequent requests COVE set the alternate coverage area for subsequent requests DATA specify a multi-line message EXPT set the expiration time for subsequent requests HELP give help information HOLD set the time at which subsequent requests are to be delivered KTAG kill a previously submitted request LEVE set the service level for subsequent requests LOGI login to server MCRE specify multiple response text and code MESS specify a single-line message MSTA return the status of a previously submitted request NOQU disable message queueing PAGE specify the destination pager PING locate/validate a pager QUIT terminate session RESE reset server state RTYP set the reply type code for subsequent requests SEND send message(s) SITE\(S1 site-specific commands (see next section) STAT\(S1 return server status SUBJ set the message text for subsequent requests
The hfaxd server will abort an active SEND operation when an ABOR command is preceded by a Telnet "Interrupt Process" (IP) signal and a Telnet "Synch" signal in the command Telnet stream.
The following non-standard or experimental commands are also supported through the SITE request.
Request Description FROMUSER specify the sender’s identity IDLE set idle-timer (in seconds) JPARM query job parameter status JQUEUE control whether or not job is queued LASTTIME set the time to terminate an unfinished job MAILADDR set the e-mail address to use for notification MAXDIALS set the maximum number of times to dial the phone MAXTRIES set the maximum number of times to try sending the page MODEM set the modem or class of modems to use NOTIFY set the e-mail notification RETRYTIME set the time to delay between job retries SCHEDPRI set the scheduling priority for the job HELP give help information, e.g., SITE HELP
Note that hfaxd requires that SNPP clients login first with the LOGI directive while RFC 1861 permits clients to submit pages anonymously.
CLIENT ACCESS CONTROL
hfaxd controls client access according to the information in the file /var/spool/hylafax/etc/hosts.hfaxd. This file defines the set of users and machines that may receive service and, optionally, defines password challenges to use in authenticating clients. Clients may be permitted access to services with or without a password challenge. Access may also be restricted based on the host machine that a request for service originates from. Consult hosts.hfaxd(5) for information on the format and content of this file. The SITE ADDUSER protocol request is provided for adding new users to a server (available only to clients with administrative privileges).
Server resources are controlled based on clients’ identities. Jobs and documents, both received and submitted, are protected by the server. Typically clients are permitted access to anything they own or that is publicly accessible. There are also administrative privileges that clients may acquire and which permit them wide access to objects that reside on the server.
A complete client-server protocol specification is still outstanding.
hfaxd operates with its root directory set to the top of the HylaFAX spooling area; /var/spool/hylafax. This is done so that clients see a virtual file hierarchy that is completely contained within the HylaFAX operating environment on the server machine. Administrators however must be aware of this action when specifying files in the hfaxd configuration file: absolute pathnames relative to the root of the spooling should be used to specify filenames.
SERVER ACCESS CONTROL
The file /var/spool/hylafax/etc/shutdown, when present, specifies when to restrict access to a server machine. When this file is present and contains valid information hfaxd will permit only users with administrative privileges to access the server. Any other users that request service will be denied access and negative server responses will include any shutdown message specified in the shutdown file. Consult hylafax-shutdown(5) for information on the format and content of this file.
The SHUT protocol request can be used to schedule a server shutdown; it is available only to clients with administrative privileges. To make a shutdown server available again the shutdown file can be deleted with the DELE protocol request (this is to be replaced with an ‘‘unshut’’ protocol request so that implementation details are not part of the protocol).
hfaxd reads configuration information from the file /etc/hylafax/hfaxd.conf each time a new server process is started (i.e. for each new client). This file uses the same conventions used by other HylaFAX configuration files; as described in hylafax-config(5). The following configuration parameters are recognized; items marked ‘‘(SNPP)’’ are used only by the SNPP support.
Tag Type Default Description AllowSortFormat boolean true Allow client to request sorting formats FaxContact string see below contact address to show in help text FileFmt string see below format string for file status results FileSortFmt string - format string for sorting file status listing IdleTimeout integer 900 client idle timeout in seconds JobFmt string see below format string for job status results JobSortFmt string - format string for sorting job status listing JobProtection octal 0444 permissions for job qfiles in sendq/doneq KillTimeMap string see below mapping from service level to job kill time (SNPP) LogFacility string daemon syslog facility name for tracing messages MaxAdminAttempts integer 5 maximum admin attempts before disconnecting MaxConsecutiveBadCmds integer 10 maximum invalid commands before disconnecting MaxIdleTimeout integer 7200 maximum client idle timeout permitted MaxLoginAttempts integer 5 maximum login attempts before disconnecting MaxMsgLength integer 128 maximum pager message length (SNPP) ModemFmt string see below format string for modem status results ModemSortFmt string - format string for sorting modem status listing PagerIDMapFile string /var/spool/hylafax/etc/pagermap name of file for mapping pager IDs (SNPP) PriorityMap string see below mapping from service level to job priority (SNPP) PublicJobQ boolean true Allow public listing access to the sendq/doneq PublicRecvQ boolean true Allow public listing access to the recvq RcvFmt string see below format string for received facsimile status results RcvSortFmt string - format string for sorting received facsimile status results listing RetryTimeMap string see below mapping from service level to job retry time (SNPP) ServerTracing integer 1 server tracing control vector ShutdownFile string /var/spool/hylafax/etc/shutdown name of shutdown control file UserAccessFile string /var/spool/hylafax/etc/hosts.hfaxd name of access control file XferLogFile string /var/spool/hylafax/etc/clientlog name of file for logging client data transfers
The configuration parameters are explained below:
|This controls whether the server accept the *SORTFMT commands which the client issues to change the server sort the listings.|
|FaxContact||The e-mail address to display as a point of contact in the help text returned to a client in response to the HELP or SITE HELP commands. By default this is ‘‘FaxMaster@hostname’’, where hostname is the fully qualified name for the machine where the server is running.|
|FileFmt||The format string to use when returning file status information with the LIST and STAT commands. Formats are specified using printf(3S) style conventions but using the field identifiers listed below. Each item can include field width, precision, left-justification, 0-filling, etc. just as for printf; e.g. %-8p for an 8-character wide, left-justified, blank-padded field containing the file protection flags.|
Format Description a Last access time c Creation time d Device number (octal) f Filename g Group identifier (decimal) i Inode number (decimal) l Link count (decimal) m Last modification time o Owner (based on file GID) p Fax-style protection flags (no group bits) q UNIX-style protection flags r Root device number (octal) s File size in bytes (decimal) u User identifier (decimal)
|The default format string is ‘‘%-7p %3l %8o %8s %-12.12m %.48f’’. It is recommended that all items include a field width so that client applications that construct headers from the format string can constrain the width of column title strings.|
|The format string to use when sorting the listing for directories using the LIST command. Follows the FileFmt formatting rules.|
|The initial/default timeout to use in timing out idle clients. This value defines the maximum amount of time (in seconds) that hfaxd will wait for a command from a client before terminating the connection. Unprivileged clients may alter the idle timeout up to the value of MaxIdleTimeout; privileged clients may set the timeout to any value.|
|JobFmt||The format string to use when returning job status information for jobs in the sendq and doneq directories. Formats are specified using printf(3S) style conventions but using the field identifiers listed below. Each item can include field width, precision, left-justification, 0-filling, etc. just as for printf; e.g. %-3j for a 3-character wide, left-justified, blank-padded field containing the job state.|
Format Description A Destination SubAddress B Destination Password C Destination company name D Total # dials/maximum # dials E Desired signalling rate F Client-specific tagline format string G Desired min-scanline time H Desired data format I Client-specified scheduling priority J Client-specified job tag string K Desired use of ECM L Destination geographic location M Notification e-mail address N Desired use of private tagline (one-character symbol) O Whether to use continuation cover page (one-character symbol) P # pages transmitted/total # pages to transmit Q Client-specified minimum acceptable signalling rate R Destination person (receiver) S Sender’s identity T Total # tries/maximum # tries U Page chopping threshold (inches) V Job done operation W Communication identifier X Job type (one-character symbol) Y Scheduled date and time Z Scheduled time in seconds since the UNIX epoch a Job state (one-character symbol) b # consecutive failed tries c Client machine name d Total # dials e Public (external) format of dialstring f # consecutive failed dials g Group identifier h Page chop handling (one-character symbol) i Current scheduling priority j Job identifier k Job kill time l Page length in mm m Assigned modem n E-mail notification handling (one-character symbol) o Job owner p # pages transmitted q Job retry time (MM::SS) r Document resolution in lines/inch s Job status information from last failure t Total # tries attempted u Maximum # tries v Client-specified dialstring w Page width in mm x Maximum # dials y Total # pages to transmit z Time to send job
|The default format string is ‘‘%-4j %3i %1a %6.6o %-12.12e %5P %5D %7z %.25s’’. This string constrains each status line to be less than 80 characters. It is recommended that all items include a field width so that client applications, such as faxstat(1) that construct headers from the format string can constrain the width of column title strings.|
|JobSortFmt||The format string to use when sorting the listing for jobs in the sendq and doneq directories. Follows the JobFmt formatting rules.|
|The file mode setting for job qfiles in the HylaFAX queues (sendq and doneq). The default setting of ‘‘0644’’ allows all users to view all job parameters in the send/done queues. If PublicJobQ is set to false, then this file mode determines the permissions of the clients to see the jobs, following the HylaFAX permission model of the group bits controlling uid permissions and the other bits controlling other permissions.|
|The mapping from SNPP service level (0-11) to job expiration time (kill time). A mapping is specified as a string of space-separate numbers where each value is the number of minutes to permit a job to run. The default mapping is ‘‘5 5 5 15 60 240 720 1440 1440 1440 1440 1440’’ which expires a job in 5 minutes for service levels 0-2, 15 minutes for level three, 60 minutes for level four, etc.|
|The symbolic name for the syslog(3) facility to use when logging error messages and informational/debugging messages requested through the ServerTracing parameter. The list of facility names is found in the system include file <syslog.h>; comparisons are case-insensitive.|
|The maximum number of unsuccessful attempts gain administrative privileges with the ADMIN command that hfaxd will permit a client before terminating the connection. Note that the count of attempts is reset if/when the client successfully gains administrative privileges.|
|The maximum number of consecutive unrecognized, unimplemented, syntactically incorrect, or otherwise unacceptable commands to permit a client before terminating the connection. This control has two purposes: to handle naive or malicious clients from sending long streams of nonsense commands to a server, and to insure that clients are forcibly terminated when a server is marked shutdown.|
|The maximum value that a client may set the idle timeout to. This value is not enforced if the client has administrative privileges.|
|The maximum number of unsuccessful attempts to login with the USER and PASS commands that hfaxd will permit a client before terminating the connection.|
|The maximum number of characters to accept in a pager message specified with the DATA or MESS commands. Messages longer than this value are rejected.|
|ModemFmt||The format string to use when returning modem status information for modems listed in the status directory. Formats are specified using printf(3S) style conventions but using the field identifiers listed below. Each item can include field width, precision, left-justification, 0-filling, etc. just as for printf; e.g. %-8h for an 8-character wide, left-justified, blank-padded field containing the name of the host the server is running on.|
Format Description h Server hostname l Local identifier string m Canonical modem name n FAX phone number r Maximum pages that can be received in a single call s Status information string t Server and session tracing levels (xxxxx:yyyyy) v Modem speaker volume as one-character symbol z A ‘‘*’’ if a faxgetty(8) process is running; otherwise ‘‘ ’’ (space)
|The default format string is ‘‘Modem %m (%n): %s’’.|
|The format string to use when sorting the listsin for modem status information in the status directory.|
|The absolute pathname of the file that contains directions for mapping pager identifiers to IXO/TAP or UCP service providers (and optionally a pager identification number). Consult pagermap(5) for information on the format and content of this file. (Note that absolute pathnames are relative to the root of the spooling area).|
|The mapping from SNPP service level (0-11) to job scheduling priority. A mapping is specified as a string of space-separate numbers where each value is the priority to assign to a job. The default mapping is ‘‘63 127 127 127 127 127 127 127 127 127 127 127’’ which assigns a high priority to service level zero and normal (default) priority to all other service levels.|
|PublicJobQ||By default, HylaFAX has always made the listings of the sendq/doneq include all jobs to any client connected to hfaxd. By setting this to false, hfaxd will also enforce it’s normal access restrictions on the listing of jobs in the sendq/doneq. These access restrictions are based on the file mode (see JobProtection ) and the logged in uid (see hosts.hfaxd )|
|By default, HylaFAX has always made the listings of the recvq include all faxes to any client connected to hfaxd. By setting this to false, hfaxd will also enforce it’s normal access restrictions on the listing of faxes in the recvq. These access restrictions are based on the file mode faxgetty (and it’s related FaxDispatch ) set for the fax, and the logged in uid (see hosts.hfaxd )|
|RcvFmt||The format string to use when returning status information for received facsimile in the recvq directory. Formats are specified using printf(3S) style conventions but using the field identifiers listed below. Each item can include field width, precision, left-justification, 0-filling, etc. just as for printf; e.g. %-3b for a 3-character wide, left-justified, blank-padded field containing the signalling rate.|
Format Description a SubAddress received from sender (if any) b Signalling rate used during receive d Data format used during receive e Error description if an error occurred during receive f Document filename (relative to the recvq directory) h Time spent receiving document (HH:MM:SS) l Page length in mm m Fax-style protection mode string (‘‘-rwxrwx’’) n File size (number of bytes) o File owner p Number of pages in document q UNIX-style protection flags r Resolution of received data s Sender identity (TSI) t Compact representation of the time when the receive happened w Page width in mm z A ‘‘*’’ if receive is going on; otherwise ‘‘ ’’ (space)
|The default format string is ‘‘%-7m %4p%1z %-8.8o %14.14s %7t %f’’. This string constrains each status line to be less than 80 characters. It is recommended that all items include a field width so that client applications, such as faxstat(1) that construct headers from the format string can constrain the width of column title strings.|
|RcvSortFmt||The format string to use when sorting the listing for received facsimile in the recvq directory. Follows the RcvFmt formatting rules.|
|The mapping from SNPP service level (0-11) to job retry time. A mapping is specified as a string of space-separate numbers where each value is the number of seconds to delay between delivery attempts. A value of zero causes retries to be scheduled using the default algorithm used by the HylaFAX job scheduler. The default mapping is ‘‘30 60 60 180 0 0 0 0 0 0 0 0’’ which retries a level 0 job after a 30 second delay, levels 1 and 2 after 60 seconds, level 3 after 3 minutes, and other jobs are retried according to the usual scheduling algorithm.|
|A number that controls the generation of tracing information by a server. areas that are individually controlled. To enable tracing of multiple areas of operation, the flag associated with each area should be bit-or’d to form the value for this tag.
Flag Description 1 (0x00001) General server operation 2 (0x00002) Client-server protocol requests and responses 4 (0x00004) File transfers from client to server 8 (0x00008) File transfers from server to client 16 (0x00010) Client logins 32 (0x00020) All network connections 64 (0x00040) FIFO messages to and from faxq(8) 128 (0x00080)TIFF Library errors and warnings 256 (0x00100)Configuration file processing
|Tracing messages are directed to syslog(3) using the facility specified with the LogFacility configuration parameter. Note that syslogd(8) must be configured to capture facility.info, facility.debug, facility.warning, and facility.err messages.|
|The absolute pathname of the server shutdown file; see hylafax-shutdown(5) for information on the format and content of this file. (Note that absolute pathnames are relative to the root of the spooling area).|
|The absolute pathname of the user access control file; see hosts.hfaxd(5) for information on the format and content of this file. (Note that absolute pathnames are relative to the root of the spooling area).|
|The absolute pathname of the file to use for logging client-server file transfers (when enabled through the ServerTracing parameter). (Note that absolute pathnames are relative to the root of the spooling area).|
|-q dir||The specified directory is treated as the spooling area. The default spooling area, /var/spool/hylafax, is defined at the time the software is built.|
|-d||Stop hfaxd from detaching itself from the controlling terminal. This option is normally used only when running hfaxd under a debugger or when hfaxd is started up from the inetd(8) process.|
|Bind to the specified bindaddress the tcp port. Please note that this argument need to be specified before the -i otherwise it will be ignored. A better approach to improve security would be to run hfaxd from xinetd, binding its service to the specific port. This will also make hylafax benefits from tcp wrappers and other options provided by xinetd.|
|-i port||Listen on the specified port for service requests and respond with the client-server protocol. The port may be specified either symbolically, e.g. ‘‘hylafax’’ or numerically. This flag may be specified multiple times to request service on multiple different ports. Each time this flag is specified, it will listen on the specified port, bound to the last -l bindaddress specified. If no -l bindaddress was specified, it will bind to the system configured default wildcard address, which could be any of IPv6, or IPv4, or both.|
|-s port||Listen on the specified port for service requests and respond with the Simple Network Paging (SNPP) protocol. The port may be specified either symbolically, e.g. ‘‘snpp’’ or numerically. This flag may be specified multiple times to request service on multiple different ports.|
|-I||Service the client-server protocol using the standard input and output. This option is useful when hfaxd is started up by inetd(8).|
|-S||Service the Simple Network Paging (SNPP) protocol using the standard input and output. This option is useful when hfaxd is started up by inetd(8).|
Diagnostics generated by hfaxd are logged using syslog(3).
/etc/hylafax/hfaxd.conf server configuration file /var/spool/hylafax spooling area /var/spool/hylafax/FIFO for submitting the job /var/spool/hylafax/sendq where job description is placed /var/spool/hylafax/sendq/seqf for assigning job identifiers /var/spool/hylafax/docq/seqf for assigning document identifiers /var/spool/hylafax/tmp temporary location of job-related files /var/spool/hylafax/docq where document files are placed /var/spool/hylafax/recvq where received facsimile are found /var/spool/hylafax/archive where archived jobs are placed /var/spool/hylafax/log for server log files /var/spool/hylafax/client for FIFO files used in communicating with faxq /var/spool/hylafax/status for server status information /var/spool/hylafax/config.device for returning server status /var/spool/hylafax/etc/hosts.hfaxdhost access control list /var/spool/hylafax/etc/shutdown server shutdown control /var/spool/hylafax/etc/pagermap SNPP pager ID mapping file
To be filled in.