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SLIPLOGIN(8)		  BSD System Manager's Manual		  SLIPLOGIN(8)

NAME
     sliplogin -- attach a serial line network interface

SYNOPSIS
     sliplogin [loginname [device]]

DESCRIPTION
     The sliplogin utility is used to turn the terminal	line on	standard input
     (or device) into a	Serial Line IP (SLIP) link to a	remote host.  To do
     this, the program searches	the file /etc/sliphome/slip.hosts for an entry
     matching loginname	(which defaults	to the current login name if omitted).
     If	a matching entry is found, the line is configured appropriately	for
     slip (8-bit transparent i/o) and converted	to SLIP	line discipline	using
     the optional line discipline parameters.

     The optional line discipline parameters consist of	one or more of the
     following;	`normal', `compress', `noicmp',	or `autocomp' which correspond
     respectively to `use normal line discipline' (no header compression),
     `enable VJ	header compression', `throw away ICMP packets',	and `auto
     enable VJ header compression' (only if the	remote end of the link also
     supports it).

     Then a shell script is invoked to initialize the slip interface with the
     appropriate local and remote IP address, netmask, etc.

     The usual initialization script is	/etc/sliphome/slip.login but, if par-
     ticular hosts need	special	initialization,	the file
     /etc/sliphome/slip.login.loginname	will be	executed instead if it exists.
     The script	is invoked with	the parameters

     slipunit  The unit	number of the slip interface assigned to this line.
	       E.g., 0 for sl0.

     speed     The speed of the	line.

     args      The arguments from the /etc/sliphome/slip.hosts entry, in order
	       starting	with loginname.

     Only the super-user may attach a network interface.  The interface	is au-
     tomatically detached when the other end hangs up or the sliplogin process
     dies.  If the kernel slip module has been configured for it, all routes
     through that interface will also disappear	at the same time.  If there is
     other processing a	site would like	done on	hangup,	the file
     /etc/sliphome/slip.logout or /etc/sliphome/slip.logout.loginname is exe-
     cuted if it exists.  It is	given the same arguments as the	login script.

   Format of /etc/sliphome/slip.hosts
     Comments (lines starting with a `#') and blank lines (or started with
     space) are	ignored.  Other	lines must start with a	loginname but the re-
     maining arguments can be whatever is appropriate for the slip.login file
     that will be executed for that name.  Arguments are separated by white
     space and follow normal sh(1) quoting conventions (however, loginname
     cannot be quoted).	 Usually, lines	have the form

	   loginname local-address remote-address netmask opt-args

     where local-address and remote-address are	the IP host names or addresses
     of	the local and remote ends of the slip line and netmask is the appro-
     priate IP netmask.	 These arguments are passed directly to	ifconfig(8).
     Opt-args are optional arguments used to configure the line.

FreeBSD	Additions
     An	additional SLIP	configuration file (if present)	is
     /etc/sliphome/slip.slparms.  If particular	hosts need different configu-
     rations, the file /etc/sliphome/slip.slparms.loginname will be parsed in-
     stead if it exists.

   Format of /etc/sliphome/slip.slparms*
     Comments (lines starting with a `#') and blank lines (or started with
     space) are	ignored.  This file contains from one to three numeric parame-
     ters separated with spaces, in order: keepalive, outfill and slunit.

     keepalive	Set SLIP "keep alive" timeout in seconds.  If FRAME_END	is not
		received in this amount	of time, sliplogin closes the line and
		exits.	The default value is no	timeout	(zero).

     outfill	Set SLIP "out fill" timeout in seconds.	 It forces at least
		one FRAME_END to be sent during	this time period, which	is
		necessary for the "keep	alive" timeout on the remote side.
		The default value is no	timeout	(zero).

     slunit	Set the	SLIP unit number directly.  Use	with caution, because
		no check is made for two interfaces with same number.  By de-
		fault sliplogin	dynamically assigns the	unit number.

     If	latter two parameters are omitted, they	will not affect	the corre-
     sponding SLIP configuration.  If any of first two parameters is equal to
     zero, it will not affect the corresponding	SLIP configuration.

EXAMPLES
     The normal	use of sliplogin is to create a	/etc/passwd entry for each le-
     gal, remote slip site with	sliplogin as the shell for that	entry.	E.g.,

     Sfoo:ikhuy6:2010:1:slip line to foo:/tmp:/usr/sbin/sliplogin

     (Our convention is	to name	the account used by remote host	hostname as
     Shostname.)  Then an entry	is added to slip.hosts that looks like:

	   Sfoo	   `hostname`	   foo	   netmask

     where `hostname` will be evaluated	by sh(1) to the	local host name	and
     netmask is	the local host IP netmask.

     Note that sliplogin must be setuid	to root	and, while not a security
     hole, moral defectives can	use it to place	terminal lines in an unusable
     state and/or deny access to legitimate users of a remote slip line.  To
     prevent this, sliplogin is	installed as user root,	group network and mode
     4550 so that only members of group	network	may run	sliplogin.  The	system
     administrator should make sure that all legitimate	users are a member of
     the correct group.

DIAGNOSTICS
     The sliplogin utility logs	various	information to the system log daemon,
     syslogd(8), with a	facility code of daemon.  The messages are listed
     here, grouped by severity level.

     Error Severity
     ioctl (TCGETS): reason
	     A TCGETS ioctl() to get the line parameters failed.

     ioctl (TCSETS): reason
	     A TCSETS ioctl() to set the line parameters failed.

     /etc/sliphome/slip.hosts: reason
	     The /etc/sliphome/slip.hosts file could not be opened.

     access denied for user
	     No	entry for user was found in /etc/sliphome/slip.hosts.

     Notice Severity
     attaching slip unit unit for loginname
	     SLIP unit unit was	successfully attached.

FILES
     /etc/sliphome/slip.hosts
	     list of host login	names and parameters.

     /etc/sliphome/slip.login
	     script executed when a connection is made.

     /etc/sliphome/slip.login.loginname
	     script executed when a connection is made by loginname.

     /etc/sliphome/slip.logout
	     script executed when a connection is lost.

     /etc/sliphome/slip.logout.loginname
	     script executed when a connection is lost by loginname.

     /etc/sliphome/slip.slparms
	     extra parameters file.

     /etc/sliphome/slip.slparms.loginname
	     extra parameters file for loginname.

     /var/run/ttyXn.if
	     contains the name of the network interface	used by	the sliplogin
	     process on	ttyXn.

     /var/run/slX.pid
	     contains the PID of the sliplogin process which is	using inter-
	     face slX.

SEE ALSO
     slattach(8), syslogd(8)

     /usr/share/examples/sliplogin

HISTORY
     The sliplogin utility appeared in 4.3BSD-Reno.

BSD				January	5, 1994				   BSD

NAME | SYNOPSIS | DESCRIPTION | FreeBSD Additions | EXAMPLES | DIAGNOSTICS | FILES | SEE ALSO | HISTORY

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