4.4BSD/usr/share/man/cat8/sliplogin.0

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

NNAAMMEE
     sslliippllooggiinn - attach a serial line network interface

SSYYNNOOPPSSIISS
     sslliippllooggiinn [_l_o_g_i_n_n_a_m_e]

DDEESSCCRRIIPPTTIIOONN
     SSlliippllooggiinn is used to turn the terminal line on standard input into a Se-
     rial Line IP (SLIP) link to a remote host.  To do this, the program
     searches the file _/_e_t_c_/_s_l_i_p_._h_o_s_t_s for an entry matching _l_o_g_i_n_n_a_m_e (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 in-
     voked to initialize the slip interface with the appropriate local and re-
     mote IP address, netmask, etc.

     The usual initialization script is _/_e_t_c_/_s_l_i_p_._l_o_g_i_n but, if particular
     hosts need special initialization, the file _/_e_t_c_/_s_l_i_p_._l_o_g_i_n_._l_o_g_i_n_n_a_m_e
     will be executed instead if it exists.  The script is invoked with the
     parameters

     _s_l_i_p_u_n_i_t  The unit number of the slip interface assigned to this line.
               E.g., 00 for ssll00.

     _s_p_e_e_d     The speed of the line.

     _a_r_g_s      The arguments from the _/_e_t_c_/_s_l_i_p_._h_o_s_t_s entry, in order starting
               with _l_o_g_i_n_n_a_m_e.

     Only the super-user may attach a network interface.  The interface is au-
     tomatically detached when the other end hangs up or the sslliippllooggiinn 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
     _/_e_t_c_/_s_l_i_p_._l_o_g_o_u_t or _/_e_t_c_/_s_l_i_p_._l_o_g_o_u_t_._l_o_g_i_n_n_a_m_e is executed if it exists.
     It is given the same arguments as the login script.

   FFoorrmmaatt ooff //eettcc//sslliipp..hhoossttss
     Comments (lines starting with a `#') and blank lines are ignored.  Other
     lines must start with a _l_o_g_i_n_n_a_m_e but the remaining arguments can be
     whatever is appropriate for the _s_l_i_p_._l_o_g_i_n file that will be executed for
     that name.  Arguments are separated by white space and follow normal
     sh(1) quoting conventions (however, _l_o_g_i_n_n_a_m_e cannot be quoted).  Usual-
     ly, lines have the form

           loginname local-address remote-address netmask opt-args

     where _l_o_c_a_l_-_a_d_d_r_e_s_s and _r_e_m_o_t_e_-_a_d_d_r_e_s_s are the IP host names or addresses
     of the local and remote ends of the slip line and _n_e_t_m_a_s_k is the appro-
     priate IP netmask.  These arguments are passed directly to ifconfig(8).
     _O_p_t_-_a_r_g_s are optional arguments used to configure the line.

EEXXAAMMPPLLEE
     The normal use of sslliippllooggiinn is to create a _/_e_t_c_/_p_a_s_s_w_d entry for each le-
     gal, remote slip site with sslliippllooggiinn as the shell for that entry.  E.g.,

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

     (Our convention is to name the account used by remote host _h_o_s_t_n_a_m_e as
     _S_h_o_s_t_n_a_m_e.) Then an entry is added to _s_l_i_p_._h_o_s_t_s that looks like:

           Sfoo    `hostname`      foo     netmask


     where _`_h_o_s_t_n_a_m_e_` will be evaluated by sh to the local host name and
     _n_e_t_m_a_s_k is the local host IP netmask.

     Note that sslliippllooggiinn 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 _s_l_i_p, that only the slip lo-
     gin accounts are put in then make sure that _/_e_t_c_/_s_l_i_p_l_o_g_i_n is in group
     _s_l_i_p and mode 4550 (setuid root, only group _s_l_i_p can execute binary).

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

     EErrrroorr SSeevveerriittyy
     iiooccttll ((TTCCGGEETTSS)):: _r_e_a_s_o_n
             A TCGETS iiooccttll() to get the line parameters failed.

     iiooccttll ((TTCCSSEETTSS)):: _r_e_a_s_o_n
             A TCSETS iiooccttll() to set the line parameters failed.

     //eettcc//sslliipp..hhoossttss:: _r_e_a_s_o_n
             The _/_e_t_c_/_s_l_i_p_._h_o_s_t_s file could not be opened.

     aacccceessss ddeenniieedd ffoorr _u_s_e_r
             No entry for _u_s_e_r was found in _/_e_t_c_/_s_l_i_p_._h_o_s_t_s.

     NNoottiiccee SSeevveerriittyy
     aattttaacchhiinngg sslliipp uunniitt _u_n_i_t ffoorr _l_o_g_i_n_n_a_m_e
             SLIP unit _u_n_i_t was successfully attached.

SSEEEE AALLSSOO
     slattach(8),  syslogd(8)

HHIISSTTOORRYY
     The sslliippllooggiinn command is currently in beta test.

4.4BSD                           June 6, 1993                                2