slattach -- attach serial lines as network interfaces


slattach [ +a | -a ] [ +c | -c ] [ -d ] [ +e | -e ] [ +f | -f ] [ +i | -i ] [ -m mtu ]
[ -p filter_tag ] [ +v | -v ] device source_address destination_address


The slattach command attaches serial lines as network interfaces. For dedicated Serial Line IP (SLIP) connections and dynamic incoming SLIP connections, the slattach command assigns the tty line device to a network interface. Do not use the -d flag for these connections. The device parameter is the name of the serial line over which SLIP will run; if the device parameter does not begin with /dev/, then /dev/ will be prepended to device. The optional baud_rate parameter sets the speed of the connection. If not specified, the default value of 9600 will be used.

For dynamic outgoing SLIP connections, the device parameter, passed with the -d argument, specifies a UUCP name to be used to contact the remote system. device must exist in an entry in the /usr/lib/uucp/Systems file as a ``sitename'' field value. TCP/IP will use this entry to establish a dialup SLIP connection with the destination_address via UUCP.

The required parameters to slattach thus have the following definitions: destination_address specifies the IP address of the remote side of the connection. device, if used with the -d flag, specifies the UUCP sitename for a dynamic outgoing SLIP connection. Otherwise, it specifies the tty line name for a dedicated or dynamic incoming SLIP connection. netmask sets the netmask for the connection interface. source_address specifies the IP address of the local side of the connection.

To detach a SLIP network interface, simply kill the slattach process and then use the following command to remove this Point-to-Point route from the Routing Table:

route delete destination_address gateway_address

Only root or users in the network group with the execsuid kernel privilege may attach (or detach) a network interface.


The following optional arguments can be used to adjust the behavior of the network interface:

+a | -a
turns proxy ARP on or off. When on, the PPP daemon looks for any SLIP interfaces without an Ethernet connection. If any such interfaces are on the same subnet as an existing Ethernet connection, the SLIP daemon adds an ARP table entry for the SLIP interface using the Ethernet connection for the same subnet.

+c | -c
turns the TCP/IP header compression mode on or off (the default setting is off).

specifies that the device parameter should be read as a UUCP sitename rather than a tty line name. Use this option only for dynamic outgoing SLIP connections.

+e | -e
turns the automatic detection and the use of TCP/IP header compression on or off (the default setting is off). If the flag +c is given, then this flag (either +e or -e) has no effect. When the flag +e is given, the SLIP module will not send any compressed TCP/IP headers until it has received and successfully uncompressed a compressed TCP/IP packet.

NOTE: If both ends of the connection use the flag +e and if neither end uses +c, then the TCP/IP header compression mode will never be turned on because neither end will take the initiative to send a compressed packet.

+f | -f
enables/disables hardware flow control.

+i | -i
turns the suppression of ICMP packets on or off (the default setting is off).

-m mtu
sets the maximum transmission unit (mtu) of the network interface to mtu (the default mtu value is 296).

NOTE: It is suggested that the mtu value for the TCP/IP packet header be 40 plus some power of 2 (for example, 296 = 40 + 2**8).

-p filter_tag
option provides a means of regulating which packets may pass through this SLIP connection. filter_tag must be the ``tag'' name of an entry in the /etc/pppfilter file; this entry holds the ``pass/no pass'' specification. The specification consists of the keyword ``pass'' and an expression. See packetfilter(SFF) for a complete description of the filter file format. All packets will be allowed to pass if -p is not specified or the filter file exists but no expression is specified with the ``pass'' keyword.

+v | -v
specifies whether to print various messages about the interface as it is being brought up (the default setting is to not print messages).

sets the speed of the connection for a dedicated or dynamic incoming SLIP connection. The default is 9600.


Use the +v option to turn on the printing of various messages.


slattach -p slip1 contty
slattach +c /dev/contty percival zapranoth 2400
slattach -p slip2 -d uu_zapranoth percival zapranoth


/etc/pppfilter packet filtering specification file

See also

devices(F), ifconfig(ADMN), ipf(ADMP), netstat(TC), packetfilter(SFF), rc2(ADM), route(ADMN), slip(ADMP), systems(F), uucp(C)

Standards conformance

slattach is conformant with:

RFC 1055 (STD 47), RFC 1144

© 2003 Caldera International, Inc. All rights reserved.
SCO OpenServer Release 5.0.7 -- 11 February 2003