| SLIPLOGIN(8) | System Manager's Manual | SLIPLOGIN(8) | 
sliplogin —
| sliplogin | [loginname] | 
sliplogin is used to turn the terminal line on standard
  input 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. 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 particular 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
Only the super-user may attach a network interface. The interface
    is automatically 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 executed if it exists. It is given the same arguments as the login
    script.
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 appropriate IP netmask. These arguments are passed directly to ifconfig(8). opt-args are optional arguments used to configure the line.
sliplogin is to create a
  /etc/passwd entry for each legal, remote slip site
  with sliplogin as the shell for that entry. For
  example:
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, a site can create a group, say
    slip, that only the slip login accounts are put in then
    make sure that /usr/sbin/sliplogin is in group
    slip and mode 4550 (setuid root, only group
    slip can execute binary).
sliplogin 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
TCGETS ioctl() to get
      the line parameters failed.
    
  TCSETS ioctl() to set
      the line parameters failed.
    
  Notice Severity
sliplogin command is currently in beta test.
| November 11, 2018 | NetBSD 9.4 |