linetd.8

linetd是一个压缩TCP高级服务器。所有的设置值都受控于命令行。与tcp服务器或sinetd类似。

.\" Process this file with
.\" groff -man -Tascii linetd.8
.\"
.TH LINETD 8 "JULY 2002" Linux "Operator Manual"
.SH NAME
linetd \- compact internet superserver
.SH SYNOPSIS
.B linetd [-a[kr] [-cdfhv] [-k[a|c|i]
.I risk
.B ] [-b 
.I address
.B ] [-u 
.I user
.B ] [-g 
.I group
.B ] [-i 
.I instances
.B ] [-l 
.I load
.B ] [-m 
.I timeout
.B ] [-n 
.I nice
.B ] [-o[c|d|r|t]] -p 
.I port 
.B [-q 
.I backlog
.B ] [-r 
.I directory
.B ] [-s[c|d|f|l|m|n|s|t|u|v] 
.I limit
.B ] [-t 
.I ttl
.B ] [-x[e|o|u]]
.I path command
.B [
.I options ...
.B ]

.SH DESCRIPTION
.B linetd
will bind a single TCP/IPv4 port and fork and exec the command given
for each incoming connection. Note that path and zeroth argument
are distinct. Also note that 
.B linetd
does not need to run as root.

.SH OPTIONS
.IP "-p port"
This option is required. It specifies the port for 
.B linetd 
to listen on.
.IP -ak
Disable keepalives.
.IP -ar
Disable the reuse of addresses.
.IP "-b address"
Bind the given address instead of all available ones.
.IP -d
Disable sanity checks. Without this option 
.B linetd
will test if the command can be executed and assume
a zeroth argument if none is given.
.IP -f
Do not fork into the background.
.IP "-g gid"
Run with given group id.
.IP -h
Terse help.
.IP "-i number"
Limit the number of child processes.
.IP "-k[a|c|i]"
Set risk to availability, confidentiality and integrity of accepting a connection.
.IP "-l load"
Suspend service above given load.
.IP "-m timeout"
Schedule an alarm signal on starting each child.
.IP "-n level"
Run at nice level.
.IP "-o[d|r|t]"
Set type of service to optimal delay, reliability or throughput.
.IP "-q value"
Keep number of connections in accept queue.
.IP "-r directory"
Change root directory.
.IP "-s[c|d|f|l|m|n|s|t|u|v] limit"
Set the resource limit of the child processes analogously to the shell ulimit command.
.IP "-t ttl"
Set the time to live counter.
.IP "-u uid"
Change user id.
.IP -v
Print version information and exit. An 
.B i
indicates a build with idsa support, not a fuel injected model.
.IP -x[e|o|u]
Set select flags passed to the
.B idsa_open(3)
call. 
.B -xe 
honours the
.B IDSA_SOCKET
environment variable,
.B -xo
enable failopen semantics, allowing access if
.B idsad(8)
is unavailable and
.B -xu
permits the uploading of IDS/A rules.

.SH "IDS/A Support"
.B linetd
uses the 
.I idsa 
library for provide structured auditing and access control.
.B linetd 
uses the simple service model schema 
.B .ssm-1
to describe its state, and 
.B .err-1
to describe error conditions. The following states
are used:
.IP "service-start"
System about to commence operation. Can be denied.
.IP "service-stop"
Normal system shutdown.
.IP "service-fail"
Abnormal system termination. The type of failure is reported 
using the 
.B err-1
scheme.
.IP "work-start"
System about to perform unit of work. Can be denied.
.IP "work-stop"
System completed a unit of work successfully.
.IP "work-fail"
System was unable to complete a unit of work.  The type of failure is reported 
using the 
.B err-1
scheme.

.SH PERFORMANCE
In its fastest configuration 
.B linetd
will generate
.B 5
system calls between successive 
.B accept(2)
calls. However, superserver architectures are not a high performance systems, 
since one of the system calls tends to be a 
.B fork(2)

.SH BUGS
Could support more protocols.

.SH ENVIRONMENT
.B IDSA_SOCKET
will be honoured if the -xe option is used.

.SH FILES
.B linetd 
does not have a configuration file. 
.B linetd 
will open
.I /proc/loadavg
to read the current load if needed.
.B linetd 
will connect to 
.I /var/run/idsa 
if idsa support is enabled and not overridden 
with -xe option. 

.SH AUTHOR
Marc Welz

.SH COPYING
.B linetd
may only be used, distributed and modified in accordance with
the terms of the
.B GPL (GNU General Public License)
as published by the
.B FSF (Free Software Foundation).

.SH "SEE ALSO"
.BR inetd (8).