ref: 3504122012e3f7ee778efa048e462510619c13b4
dir: /sys/man/8/listen/
.TH LISTEN 8 .SH NAME listen, listen1, tcp7, tcp9, tcp19, tcp21, tcp23, tcp25, tcp53, tcp110, tcp113, tcp143, tcp445, tcp513, tcp515, tcp564, tcp565, tcp566, tcp567, tcp993, tcp995, tcp1723, tcp17019, tcp17020 \- listen for calls on a network device .SH SYNOPSIS .B aux/listen .RB [ -iq ] .RB [ -d .IR srvdir ] .RB [ -t .IR trustsrvdir ] .RB [ -n .IR namespace ] .RB [ -p .IR maxprocs ] .RB [ -o .IR copt ] .RB [ -O .IR sopt ] .RB [ -a .IR addr ] .RI [ proto ] .PP .B aux/listen1 [ .B -1tv ] .RB [ -n .IR namespace ] .RB [ -p .IR maxprocs ] .RB [ -o .IR copt ] .RB [ -O .IR sopt ] .I addr .I cmd [ .I args... ] .SH DESCRIPTION .I Listen listens on a network for inbound calls to local services. .I Proto is the network protocol on which to listen, by default .BR tcp . Incoming calls to any address .B * are accepted unless .I addr is specified with the .B -a option. The services available are executable, non-empty files in .I srvdir or .IR trustsrvdir . If neither .I srvdir nor .I trustsrvdir is given, .I listen looks for executable files in .BR /bin/service . Services found in .I srvdir are executed as user .BR none ; services found in .I trustsrvdir are executed as the user who started .IR listen . When changing user to .BR none , a new namespace is created, usually by executing .BR /lib/namespace , but .B -n selects an alternate .IR namespace . The .B -p option limits the number of processes that .I listen spawns to service the connections. If the .I maxprocs limit is reached, .I listen will log the event and delay servicing until the number of connection processes drops below the limit again. A .I maxprocs smaller or equal zero means no limit (default). The .B -o and .B -O options cause protocol-specific control messages to be written to the control file of the listening server connection .B -O or the incoming client connection .BR -o . They can be specified multiple times. See .IR ip (3) for details. Option .B -q suppresses affirmative log information. Option .B -i suppresses the periodic scan of the service directories for changes. .PP Service names are made by concatenating the name of the network with the name of the service or port. For example, an inbound call on the TCP network for port 565 executes service .BR tcp565 . .PP Services may have individual .IR namespace (6) files specified within .IR srvdir . If provided, the namespace is used as the parent for each connection to the corresponding service. Namespace files are found by appending a .namespace suffix to the service name. .PP At least the following services are available in .BR /bin/service . .TF \ tcp0000 .TP .B tcp564 serve a piece of the name space using the Plan 9 file system protocol, with authentication via .I Tauth (in .IR attach (5)), no encryption, and multiplex multiple users on a single connection (used by .IR srv (4), and also by Unix systems to see Plan 9 files). .TP .B tcp17019 server for .IR rcpu (1), replaces .IR rx , .IR import and .IR cpu using TLS for encryption. .TP .B tcp17020 TLS encrypted 9P fileserver (t9fs) for .I srvtls (see .IR srv (4)). .TP .B tcp7 echo any bytes received (bit mirror) .TP .B tcp9 consume any bytes received (bit bucket) .TP .B tcp19 .B chargen service. .TP .B tcp21 FTP daemon .TP .B tcp23 .B telnet terminal connection. .TP .B tcp25 mail delivery. .TP .B tcp53 TCP port for DNS. .TP .B tcp110 POP3 port. .TP .B tcp113 .B Ident port (always reports .BR none ). .TP .B tcp143 IMAP4rev1 port. .TP .B tcp445 CIFS/SMB file sharing. .TP .B tcp513 .B rlogin terminal connection. .TP .B tcp515 LP daemon; see .IR lp (8). .TP .B tcp565 report the address of the incoming call. .TP .B tcp993 Secure IMAP4rev1 port. .TP .B tcp995 Secure POP3 port. .TP .B tcp1723 PPTP (point-to-point tunnelling protocol) service. .PD .PP At least the following services are available in .BR /bin/service.auth , the usual .IR trustsrvdir . .TF \ tcp0000 .TP .B tcp566 validate a SecureNet box. .TP .B tcp567 Plan 9 authentication-ticket service. .PD .PP .I Listen1 is a lightweight listener intended for personal use, modeled from Inferno's .\" write out this way so automatic programs .\" don't try to make it into a real man page reference. \fIlisten\fR(1). It announces on .IR address , running .I cmd .I args... for each incoming connection; the network directory is passed in the environment as .BR $net . Option .B -t causes .I listen1 to run as the invoking user; the default is to become .B none before listening. Option .B -1 arms a one-shot listener; it terminates listen1 upon receiving a single call. Option .B -v causes verbose logging on standard output. See .B /rc/bin/tlssrvtunnel for an example. .SH FILES .TF /env/sysname .TP .B /net/tcp by convention, TCP device bind point .SH SOURCE .B /sys/src/cmd/aux/listen*.c .br .B /rc/bin/service* .SH "SEE ALSO" .IR authsrv (6), .IR dial (2), .IR ip (3) .SH BUGS .IR Srvdir , .IR trustsrvdir and .I namespace must all be absolute path names.