587 lines
22 KiB
Perl
587 lines
22 KiB
Perl
|
.\" Copyright (c) 1980, 1986, 1988, 1993 The Regents of the University of California.
|
||
|
|
.\" All rights reserved.
|
||
|
|
.\"
|
||
|
|
.\" Redistribution and use in source and binary forms, with or without
|
||
|
|
.\" modification, are permitted provided that the following conditions
|
||
|
|
.\" are met:
|
||
|
|
.\" 1. Redistributions of source code must retain the above copyright
|
||
|
|
.\" notice, this list of conditions and the following disclaimer.
|
||
|
|
.\" 2. Redistributions in binary form must reproduce the above copyright
|
||
|
|
.\" notice, this list of conditions and the following disclaimer in the
|
||
|
|
.\" documentation and/or other materials provided with the distribution.
|
||
|
|
.\" 3. All advertising materials mentioning features or use of this software
|
||
|
|
.\" must display the following acknowledgement:
|
||
|
|
.\" This product includes software developed by the University of
|
||
|
|
.\" California, Berkeley and its contributors.
|
||
|
|
.\" 4. Neither the name of the University nor the names of its contributors
|
||
|
|
.\" may be used to endorse or promote products derived from this software
|
||
|
|
.\" without specific prior written permission.
|
||
|
|
.\"
|
||
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
|
||
|
|
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
||
|
|
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
||
|
|
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
|
||
|
|
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
||
|
|
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
||
|
|
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
||
|
|
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
||
|
|
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
||
|
|
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
||
|
|
.\" SUCH DAMAGE.
|
||
|
|
.\"
|
||
|
|
.\" @(#)5.t 8.1 (Berkeley) 7/27/93
|
||
|
|
.\"
|
||
|
|
.ds lq ``
|
||
|
|
.ds rq ''
|
||
|
|
.ds LH "Installing/Operating \*(4B
|
||
|
|
.ds RH Network setup
|
||
|
|
.ds CF \*(Dy
|
||
|
|
.Sh 1 "Network setup"
|
||
|
|
.PP
|
||
|
|
\*(4B provides support for the standard Internet
|
||
|
|
protocols IP, ICMP, TCP, and UDP. These protocols may be used
|
||
|
|
on top of a variety of hardware devices ranging from
|
||
|
|
serial lines to local area network controllers
|
||
|
|
for the Ethernet. Network services are split between the
|
||
|
|
kernel (communication protocols) and user programs (user
|
||
|
|
services such as TELNET and FTP). This section describes
|
||
|
|
how to configure your system to use the Internet networking support.
|
||
|
|
\*(4B also supports the Xerox Network Systems (NS) protocols.
|
||
|
|
IDP and SPP are implemented in the kernel,
|
||
|
|
and other protocols such as Courier run at the user level.
|
||
|
|
\*(4B provides some support for the ISO OSI protocols CLNP
|
||
|
|
TP4, and ESIS. User level process
|
||
|
|
complete the application protocols such as X.400 and X.500.
|
||
|
|
.Sh 2 "System configuration"
|
||
|
|
.PP
|
||
|
|
To configure the kernel to include the Internet communication
|
||
|
|
protocols, define the INET option.
|
||
|
|
Xerox NS support is enabled with the NS option.
|
||
|
|
ISO OSI support is enabled with the ISO option.
|
||
|
|
In either case, include the pseudo-devices
|
||
|
|
``pty'', and ``loop'' in your machine's configuration
|
||
|
|
file.
|
||
|
|
The ``pty'' pseudo-device forces the pseudo terminal device driver
|
||
|
|
to be configured into the system, see
|
||
|
|
.Xr pty (4),
|
||
|
|
while the ``loop'' pseudo-device forces inclusion of the software loopback
|
||
|
|
interface driver.
|
||
|
|
The loop driver is used in network testing
|
||
|
|
and also by the error logging system.
|
||
|
|
.PP
|
||
|
|
If you are planning to use the Internet network facilities on a 10Mb/s
|
||
|
|
Ethernet, the pseudo-device ``ether'' should also be included
|
||
|
|
in the configuration; this forces inclusion of the Address Resolution
|
||
|
|
Protocol module used in mapping between 48-bit Ethernet
|
||
|
|
and 32-bit Internet addresses.
|
||
|
|
.PP
|
||
|
|
Before configuring the appropriate networking hardware, you should
|
||
|
|
consult the manual pages in section 4 of the Programmer's Manual
|
||
|
|
selecting the appropriate interfaces for your architecture.
|
||
|
|
.PP
|
||
|
|
All network interface drivers including the loopback interface,
|
||
|
|
require that their host address(es) be defined at boot time.
|
||
|
|
This is done with
|
||
|
|
.Xr ifconfig (8)
|
||
|
|
commands included in the
|
||
|
|
.Pn /etc/netstart
|
||
|
|
file.
|
||
|
|
Interfaces that are able to dynamically deduce the host
|
||
|
|
part of an address may check that the host part of the address is correct.
|
||
|
|
The manual page for each network interface
|
||
|
|
describes the method used to establish a host's address.
|
||
|
|
.Xr Ifconfig (8)
|
||
|
|
can also be used to set options for the interface at boot time.
|
||
|
|
Options are set independently for each interface, and
|
||
|
|
apply to all packets sent using that interface.
|
||
|
|
Alternatively, translations for such hosts may be set in advance
|
||
|
|
or ``published'' by a \*(4B host by use of the
|
||
|
|
.Xr arp (8)
|
||
|
|
command.
|
||
|
|
Note that the use of trailer link-level is now negotiated between \*(4B hosts
|
||
|
|
using ARP,
|
||
|
|
and it is thus no longer necessary to disable the use of trailers
|
||
|
|
with
|
||
|
|
.Xr ifconfig .
|
||
|
|
.PP
|
||
|
|
The OSI equivalent to ARP is ESIS (End System to Intermediate System Routing
|
||
|
|
Protocol); running this protocol is mandatory, however one can manually add
|
||
|
|
translations for machines that do not participate by use of the
|
||
|
|
.Xr route (8)
|
||
|
|
command.
|
||
|
|
Additional information is provided in the manual page describing
|
||
|
|
.Xr ESIS (4).
|
||
|
|
.PP
|
||
|
|
To use the pseudo terminals just configured, device
|
||
|
|
entries must be created in the
|
||
|
|
.Pn /dev
|
||
|
|
directory. To create 32
|
||
|
|
pseudo terminals (plenty, unless you have a heavy network load)
|
||
|
|
execute the following commands.
|
||
|
|
.DS
|
||
|
|
\fB#\fP \fIcd /dev\fP
|
||
|
|
\fB#\fP \fIMAKEDEV pty0 pty1\fP
|
||
|
|
.DE
|
||
|
|
More pseudo terminals may be made by specifying
|
||
|
|
.Pn pty2 ,
|
||
|
|
.Pn pty3 ,
|
||
|
|
etc. The kernel normally includes support for 32 pseudo terminals
|
||
|
|
unless the configuration file specifies a different number.
|
||
|
|
Each pseudo terminal really consists of two files in
|
||
|
|
.Pn /dev :
|
||
|
|
a master and a slave. The master pseudo terminal file is named
|
||
|
|
.Pn /dev/ptyp? ,
|
||
|
|
while the slave side is
|
||
|
|
.Pn /dev/ttyp? .
|
||
|
|
Pseudo terminals are also used by several programs not related to the network.
|
||
|
|
In addition to creating the pseudo terminals,
|
||
|
|
be sure to install them in the
|
||
|
|
.Pn /etc/ttys
|
||
|
|
file (with a `none' in the second column so no
|
||
|
|
.Xr getty
|
||
|
|
is started).
|
||
|
|
.Sh 2 "Local subnets"
|
||
|
|
.PP
|
||
|
|
In \*(4B the Internet support
|
||
|
|
includes the notion of ``subnets''. This is a mechanism
|
||
|
|
by which multiple local networks may appears as a single Internet
|
||
|
|
network to off-site hosts. Subnetworks are useful because
|
||
|
|
they allow a site to hide their local topology, requiring only a single
|
||
|
|
route in external gateways;
|
||
|
|
it also means that local network numbers may be locally administered.
|
||
|
|
The standard describing this change in Internet addressing is RFC-950.
|
||
|
|
.PP
|
||
|
|
To set up local subnets one must first decide how the available
|
||
|
|
address space (the Internet ``host part'' of the 32-bit address)
|
||
|
|
is to be partitioned.
|
||
|
|
Sites with a class A network
|
||
|
|
number have a 24-bit host address space with which to work, sites with a
|
||
|
|
class B network number have a 16-bit host address space, while sites with
|
||
|
|
a class C network number have an 8-bit host address space\**.
|
||
|
|
.FS
|
||
|
|
If you are unfamiliar with the Internet addressing structure, consult
|
||
|
|
``Address Mappings'', Internet RFC-796, J. Postel; available from
|
||
|
|
the Internet Network Information Center at SRI.
|
||
|
|
.FE
|
||
|
|
To define local subnets you must steal some bits
|
||
|
|
from the local host address space for use in extending the network
|
||
|
|
portion of the Internet address. This reinterpretation of Internet
|
||
|
|
addresses is done only for local networks; i.e. it is not visible
|
||
|
|
to hosts off-site. For example, if your site has a class B network
|
||
|
|
number, hosts on this network have an Internet address that contains
|
||
|
|
the network number, 16 bits, and the host number, another
|
||
|
|
16 bits. To define 254 local subnets, each
|
||
|
|
possessing at most 255 hosts, 8 bits may be taken from the local part.
|
||
|
|
(The use of subnets 0 and all-1's, 255 in this example, is discouraged
|
||
|
|
to avoid confusion about broadcast addresses.)
|
||
|
|
These new network
|
||
|
|
numbers are then constructed by concatenating the original 16-bit network
|
||
|
|
number with the extra 8 bits containing the local subnet number.
|
||
|
|
.PP
|
||
|
|
The existence of local subnets is communicated to the system at the time a
|
||
|
|
network interface is configured with the
|
||
|
|
.I netmask
|
||
|
|
option to the
|
||
|
|
.Xr ifconfig
|
||
|
|
program. A ``network mask'' is specified to define the
|
||
|
|
portion of the Internet address that is to be considered the network part
|
||
|
|
for that network.
|
||
|
|
This mask normally contains the bits corresponding to the standard
|
||
|
|
network part as well as the portion of the local part
|
||
|
|
that has been assigned to subnets.
|
||
|
|
If no mask is specified when the address is set,
|
||
|
|
it will be set according to the class of the network.
|
||
|
|
For example, at Berkeley (class B network 128.32) 8 bits
|
||
|
|
of the local part have been reserved for defining subnets;
|
||
|
|
consequently the
|
||
|
|
.Pn /etc/netstart
|
||
|
|
file contains lines of the form
|
||
|
|
.DS
|
||
|
|
.ft CW
|
||
|
|
/sbin/ifconfig le0 netmask 0xffffff00 128.32.1.7
|
||
|
|
.DE
|
||
|
|
This specifies that for interface ``le0'', the upper 24 bits of
|
||
|
|
the Internet address should be used in calculating network numbers
|
||
|
|
(netmask 0xffffff00), and the interface's Internet address is
|
||
|
|
``128.32.1.7'' (host 7 on network 128.32.1). Hosts \fIm\fP on
|
||
|
|
sub-network \fIn\fP of this network would then have addresses of
|
||
|
|
the form ``128.32.\fIn\fP.\fIm\fP''; for example, host
|
||
|
|
99 on network 129 would have an address ``128.32.129.99''.
|
||
|
|
For hosts with multiple interfaces, the network mask should
|
||
|
|
be set for each interface,
|
||
|
|
although in practice only the mask of the first interface on each network
|
||
|
|
is really used.
|
||
|
|
.Sh 2 "Internet broadcast addresses"
|
||
|
|
.PP
|
||
|
|
The address defined as the broadcast address for Internet networks
|
||
|
|
according to RFC-919 is the address with a host part of all 1's.
|
||
|
|
The address used by 4.2BSD was the address with a host part of 0.
|
||
|
|
\*(4B uses the standard broadcast address (all 1's) by default,
|
||
|
|
but allows the broadcast address to be set (with
|
||
|
|
.Xr ifconfig )
|
||
|
|
for each interface.
|
||
|
|
This allows networks consisting of both 4.2BSD, \*(Ps and \*(4B hosts
|
||
|
|
to coexist while the upgrade process proceeds.
|
||
|
|
In the presence of subnets, the broadcast address uses the subnet field
|
||
|
|
as for normal host addresses, with the remaining host part set to 1's
|
||
|
|
(or 0's, on a network that has not yet been converted).
|
||
|
|
\*(4B hosts recognize and accept packets
|
||
|
|
sent to the logical-network broadcast address as well as those sent
|
||
|
|
to the subnet broadcast address, and when using an all-1's broadcast,
|
||
|
|
also recognize and receive packets sent to host 0 as a broadcast.
|
||
|
|
.Sh 2 "Routing"
|
||
|
|
.PP
|
||
|
|
If your environment allows access to networks not directly
|
||
|
|
attached to your host you will need to set up routing information
|
||
|
|
to allow packets to be properly routed. Two schemes are
|
||
|
|
supported by the system. The first scheme
|
||
|
|
employs a routing table management daemon.
|
||
|
|
Optimally, you should use the routing daemon
|
||
|
|
.Xr gated
|
||
|
|
available from Cornell university.
|
||
|
|
We use it on our systems and it works well,
|
||
|
|
especially for multi-homed hosts using Serial Line IP (SLIP).
|
||
|
|
Unfortunately, we were not able to obtain permission to
|
||
|
|
include it on \*(4B.
|
||
|
|
.PP
|
||
|
|
If you do not wish to or cannot obtain
|
||
|
|
.Xr gated ,
|
||
|
|
the distribution does include
|
||
|
|
.Xr routed (8)
|
||
|
|
to maintain the system routing tables. The routing daemon
|
||
|
|
uses a variant of the Xerox Routing Information Protocol
|
||
|
|
to maintain up to date routing tables in a cluster of local
|
||
|
|
area networks. By using the
|
||
|
|
.Pn /etc/gateways
|
||
|
|
file, the routing daemon can also be used to initialize static routes
|
||
|
|
to distant networks (see the next section for further discussion).
|
||
|
|
When the routing daemon is started up
|
||
|
|
(usually from
|
||
|
|
.Pn /etc/rc )
|
||
|
|
it reads
|
||
|
|
.Pn /etc/gateways
|
||
|
|
if it exists and installs those routes defined there,
|
||
|
|
then broadcasts on each local network
|
||
|
|
to which the host is attached to find other instances of the routing
|
||
|
|
daemon. If any responses are received, the routing daemons
|
||
|
|
cooperate in maintaining a globally consistent view of routing
|
||
|
|
in the local environment. This view can be extended to include
|
||
|
|
remote sites also running the routing daemon by setting up suitable
|
||
|
|
entries in
|
||
|
|
.Pn /etc/gateways ;
|
||
|
|
consult
|
||
|
|
.Xr routed (8)
|
||
|
|
for a more thorough discussion.
|
||
|
|
.PP
|
||
|
|
The second approach is to define a default or wildcard
|
||
|
|
route to a smart
|
||
|
|
gateway and depend on the gateway to provide ICMP routing
|
||
|
|
redirect information to dynamically create a routing data
|
||
|
|
base. This is done by adding an entry of the form
|
||
|
|
.DS
|
||
|
|
.ft CW
|
||
|
|
/sbin/route add default \fIsmart-gateway\fP 1
|
||
|
|
.DE
|
||
|
|
to
|
||
|
|
.Pn /etc/netstart ;
|
||
|
|
see
|
||
|
|
.Xr route (8)
|
||
|
|
for more information. The default route
|
||
|
|
will be used by the system as a ``last resort''
|
||
|
|
in routing packets to their destination. Assuming the gateway
|
||
|
|
to which packets are directed is able to generate the proper
|
||
|
|
routing redirect messages, the system will then add routing
|
||
|
|
table entries based on the information supplied. This approach
|
||
|
|
has certain advantages over the routing daemon, but is
|
||
|
|
unsuitable in an environment where there are only bridges (i.e.
|
||
|
|
pseudo gateways that, for instance, do not generate routing
|
||
|
|
redirect messages). Further, if the
|
||
|
|
smart gateway goes down there is no alternative, save manual
|
||
|
|
alteration of the routing table entry, to maintaining service.
|
||
|
|
.PP
|
||
|
|
The system always listens, and processes, routing redirect
|
||
|
|
information, so it is possible to combine both of the above
|
||
|
|
facilities. For example, the routing table management process
|
||
|
|
might be used to maintain up to date information about routes
|
||
|
|
to geographically local networks, while employing the wildcard
|
||
|
|
routing techniques for ``distant'' networks. The
|
||
|
|
.Xr netstat (1)
|
||
|
|
program may be used to display routing table contents as well
|
||
|
|
as various routing oriented statistics. For example,
|
||
|
|
.DS
|
||
|
|
\fB#\fP \fInetstat \-r\fP
|
||
|
|
.DE
|
||
|
|
will display the contents of the routing tables, while
|
||
|
|
.DS
|
||
|
|
\fB#\fP \fInetstat \-r \-s\fP
|
||
|
|
.DE
|
||
|
|
will show the number of routing table entries dynamically
|
||
|
|
created as a result of routing redirect messages, etc.
|
||
|
|
.Sh 2 "Use of \*(4B machines as gateways"
|
||
|
|
.PP
|
||
|
|
Several changes have been made in \*(4B in the area of gateway support
|
||
|
|
(or packet forwarding, if one prefers).
|
||
|
|
A new configuration option, GATEWAY, is used when configuring
|
||
|
|
a machine to be used as a gateway.
|
||
|
|
This option increases the size of the routing hash tables in the kernel.
|
||
|
|
Unless configured with that option,
|
||
|
|
hosts with only a single non-loopback interface never attempt
|
||
|
|
to forward packets or to respond with ICMP error messages to misdirected
|
||
|
|
packets.
|
||
|
|
This change reduces the problems that may occur when different hosts
|
||
|
|
on a network disagree on the network number or broadcast address.
|
||
|
|
Another change is that \*(4B machines that forward packets back through
|
||
|
|
the same interface on which they arrived
|
||
|
|
will send ICMP redirects to the source host if it is on the same network.
|
||
|
|
This improves the interaction of \*(4B gateways with hosts that configure
|
||
|
|
their routes via default gateways and redirects.
|
||
|
|
The generation of redirects may be disabled with the configuration option
|
||
|
|
IPSENDREDIRECTS=0 or while the system is running by using the command:
|
||
|
|
.DS
|
||
|
|
.ft CW
|
||
|
|
sysctl -w net.inet.ip.redirect=0
|
||
|
|
.DE
|
||
|
|
in environments where it may cause difficulties.
|
||
|
|
.Sh 2 "Network databases"
|
||
|
|
.PP
|
||
|
|
Several data files are used by the network library routines
|
||
|
|
and server programs. Most of these files are host independent
|
||
|
|
and updated only rarely.
|
||
|
|
.br
|
||
|
|
.ne 1i
|
||
|
|
.TS
|
||
|
|
lfC l l.
|
||
|
|
File Manual reference Use
|
||
|
|
_
|
||
|
|
/etc/hosts \fIhosts\fP\|(5) local host names
|
||
|
|
/etc/networks \fInetworks\fP\|(5) network names
|
||
|
|
/etc/services \fIservices\fP\|(5) list of known services
|
||
|
|
/etc/protocols \fIprotocols\fP\|(5) protocol names
|
||
|
|
/etc/hosts.equiv \fIrshd\fP\|(8) list of ``trusted'' hosts
|
||
|
|
/etc/netstart \fIrc\fP\|(8) command script for initializing network
|
||
|
|
/etc/rc \fIrc\fP\|(8) command script for starting standard servers
|
||
|
|
/etc/rc.local \fIrc\fP\|(8) command script for starting local servers
|
||
|
|
/etc/ftpusers \fIftpd\fP\|(8) list of ``unwelcome'' ftp users
|
||
|
|
/etc/hosts.lpd \fIlpd\fP\|(8) list of hosts allowed to access printers
|
||
|
|
/etc/inetd.conf \fIinetd\fP\|(8) list of servers started by \fIinetd\fP
|
||
|
|
.TE
|
||
|
|
The files distributed are set up for Internet hosts.
|
||
|
|
Local networks and hosts should be added to describe the local
|
||
|
|
configuration; the Berkeley entries may serve as examples
|
||
|
|
(see also the section on
|
||
|
|
.Pn /etc/hosts ).
|
||
|
|
Network numbers will have to be chosen for each Ethernet.
|
||
|
|
For sites connected to the Internet,
|
||
|
|
the normal channels should be used for allocation of network
|
||
|
|
numbers (contact hostmaster@SRI-NIC.ARPA).
|
||
|
|
For other sites,
|
||
|
|
these could be chosen more or less arbitrarily,
|
||
|
|
but it is generally better to request official numbers
|
||
|
|
to avoid conversion if a connection to the Internet (or others on the Internet)
|
||
|
|
is ever established.
|
||
|
|
.Sh 3 "Network servers"
|
||
|
|
.PP
|
||
|
|
Most network servers are automatically started up at boot time
|
||
|
|
by the command file
|
||
|
|
.Pn /etc/rc
|
||
|
|
or by the Internet daemon (see below).
|
||
|
|
These include the following:
|
||
|
|
.TS
|
||
|
|
lfC l l.
|
||
|
|
Program Server Started by
|
||
|
|
_
|
||
|
|
/usr/sbin/syslogd error logging server \f(CW/etc/rc\fP
|
||
|
|
/usr/sbin/named Internet name server \f(CW/etc/rc\fP
|
||
|
|
/sbin/routed routing table management daemon \f(CW/etc/rc\fP
|
||
|
|
/usr/sbin/rwhod system status daemon \f(CW/etc/rc\fP
|
||
|
|
/usr/sbin/timed time synchronization daemon \f(CW/etc/rc\fP
|
||
|
|
/usr/sbin/sendmail SMTP server \f(CW/etc/rc\fP
|
||
|
|
/usr/libexec/rshd shell server inetd
|
||
|
|
/usr/libexec/rexecd exec server inetd
|
||
|
|
/usr/libexec/rlogind login server inetd
|
||
|
|
/usr/libexec/telnetd TELNET server inetd
|
||
|
|
/usr/libexec/ftpd FTP server inetd
|
||
|
|
/usr/libexec/fingerd Finger server inetd
|
||
|
|
/usr/libexec/tftpd TFTP server inetd
|
||
|
|
.TE
|
||
|
|
Consult the manual pages and accompanying documentation (particularly
|
||
|
|
for named and sendmail) for details about their operation.
|
||
|
|
.PP
|
||
|
|
The use of
|
||
|
|
.Xr routed
|
||
|
|
and
|
||
|
|
.Xr rwhod
|
||
|
|
is controlled by shell
|
||
|
|
variables set in
|
||
|
|
.Pn /etc/netstart .
|
||
|
|
By default,
|
||
|
|
.Xr routed
|
||
|
|
is used, but
|
||
|
|
.Xr rwhod
|
||
|
|
is not; they are enabled by setting the variables \fIroutedflags\fP and
|
||
|
|
.Xr rwhod
|
||
|
|
to strings other than ``NO.''
|
||
|
|
The value of \fIroutedflags\fP provides host-specific options to
|
||
|
|
.Xr routed .
|
||
|
|
For example,
|
||
|
|
.DS
|
||
|
|
.ft CW
|
||
|
|
routedflags=-q
|
||
|
|
rwhod=NO
|
||
|
|
.DE
|
||
|
|
would run
|
||
|
|
.Xr "routed -q"
|
||
|
|
and would not run
|
||
|
|
.Xr rwhod .
|
||
|
|
.PP
|
||
|
|
To have other network servers started as well,
|
||
|
|
commands of the following sort should be placed in the site-dependent file
|
||
|
|
.Pn /etc/rc.local .
|
||
|
|
.DS
|
||
|
|
.ft CW
|
||
|
|
if [ -f /usr/sbin/timed ]; then
|
||
|
|
/usr/sbin/timed & echo -n ' timed' >/dev/console
|
||
|
|
f\&i
|
||
|
|
.DE
|
||
|
|
.Sh 3 "Internet daemon"
|
||
|
|
.PP
|
||
|
|
In \*(4B most of the servers for user-visible services are started up by a
|
||
|
|
``super server'', the Internet daemon. The Internet
|
||
|
|
daemon,
|
||
|
|
.Pn /usr/sbin/inetd ,
|
||
|
|
acts as a master server for
|
||
|
|
programs specified in its configuration file,
|
||
|
|
.Pn /etc/inetd.conf ,
|
||
|
|
listening for service requests for these servers, and starting
|
||
|
|
up the appropriate program whenever a request is received.
|
||
|
|
The configuration file contains lines containing a service
|
||
|
|
name (as found in
|
||
|
|
.Pn /etc/services ),
|
||
|
|
the type of socket the
|
||
|
|
server expects (e.g. stream or dgram), the protocol to be
|
||
|
|
used with the socket (as found in
|
||
|
|
.Pn /etc/protocols ),
|
||
|
|
whether to wait for each server to complete before starting up another,
|
||
|
|
the user name by which the server should run, the server
|
||
|
|
program's name, and at most five arguments to pass to the
|
||
|
|
server program.
|
||
|
|
Some trivial services are implemented internally in
|
||
|
|
.Xr inetd ,
|
||
|
|
and their servers are listed as ``internal.''
|
||
|
|
For example, an entry for the file
|
||
|
|
transfer protocol server would appear as
|
||
|
|
.DS
|
||
|
|
.ft CW
|
||
|
|
ftp stream tcp nowait root /usr/libexec/ftpd ftpd
|
||
|
|
.DE
|
||
|
|
Consult
|
||
|
|
.Xr inetd (8)
|
||
|
|
for more detail on the format of the configuration file
|
||
|
|
and the operation of the Internet daemon.
|
||
|
|
.Sh 3 "The \f(CW/etc/hosts.equiv\fP file"
|
||
|
|
.PP
|
||
|
|
The remote login and shell servers use an
|
||
|
|
authentication scheme based on trusted hosts. The
|
||
|
|
.Pn hosts.equiv
|
||
|
|
file contains a list of hosts that are considered trusted
|
||
|
|
and, under a single administrative control. When a user
|
||
|
|
contacts a remote login or shell server requesting service,
|
||
|
|
the client process passes the user's name and the official
|
||
|
|
name of the host on which the client is located. In the simple
|
||
|
|
case, if the host's name is located in
|
||
|
|
.Pn hosts.equiv
|
||
|
|
and the user has an account on the server's machine, then service
|
||
|
|
is rendered (i.e. the user is allowed to log in, or the command
|
||
|
|
is executed). Users may expand this ``equivalence'' of
|
||
|
|
machines by installing a
|
||
|
|
.Pn \&.rhosts
|
||
|
|
file in their login directory.
|
||
|
|
The root login is handled specially, bypassing the
|
||
|
|
.Pn hosts.equiv
|
||
|
|
file, and using only the
|
||
|
|
.Pn /.rhosts
|
||
|
|
file.
|
||
|
|
.PP
|
||
|
|
Thus, to create a class of equivalent machines, the
|
||
|
|
.Pn hosts.equiv
|
||
|
|
file should contain the \fIofficial\fP names for those machines.
|
||
|
|
If you are running the name server, you may omit the domain part
|
||
|
|
of the host name for machines in your local domain.
|
||
|
|
For example, four machines on our local
|
||
|
|
network are considered trusted, so the
|
||
|
|
.Pn hosts.equiv
|
||
|
|
file is of the form:
|
||
|
|
.DS
|
||
|
|
.ft CW
|
||
|
|
vangogh.CS.Berkeley.EDU
|
||
|
|
picasso.CS.Berkeley.EDU
|
||
|
|
okeeffe.CS.Berkeley.EDU
|
||
|
|
.DE
|
||
|
|
.Sh 3 "The \f(CW/etc/ftpusers\fP file"
|
||
|
|
.PP
|
||
|
|
The FTP server included in the system provides support for an
|
||
|
|
anonymous FTP account. Because of the inherent security problems
|
||
|
|
with such a facility you should read this section carefully if
|
||
|
|
you consider providing such a service.
|
||
|
|
.PP
|
||
|
|
An anonymous account is enabled by creating a user
|
||
|
|
.Xr ftp .
|
||
|
|
When a client uses the anonymous account a
|
||
|
|
.Xr chroot (2)
|
||
|
|
system call is performed by the server to restrict the client
|
||
|
|
from moving outside that part of the filesystem where the
|
||
|
|
user ftp home directory is located. Because a
|
||
|
|
.Xr chroot
|
||
|
|
call is used, certain programs and files used by the server
|
||
|
|
process must be placed in the ftp home directory.
|
||
|
|
Further, one must be
|
||
|
|
sure that all directories and executable images are unwritable.
|
||
|
|
The following directory setup is recommended. The
|
||
|
|
use of the
|
||
|
|
.Xr awk
|
||
|
|
commands to copy the
|
||
|
|
.Pn /etc/passwd
|
||
|
|
and
|
||
|
|
.Pn /etc/group
|
||
|
|
files are \fBSTRONGLY\fP recommended.
|
||
|
|
.DS
|
||
|
|
\fB#\fP \fIcd ~ftp\fP
|
||
|
|
\fB#\fP \fIchmod 555 .; chown ftp .; chgrp ftp .\fP
|
||
|
|
\fB#\fP \fImkdir bin etc pub\fP
|
||
|
|
\fB#\fP \fIchown root bin etc\fP
|
||
|
|
\fB#\fP \fIchmod 555 bin etc\fP
|
||
|
|
\fB#\fP \fIchown ftp pub\fP
|
||
|
|
\fB#\fP \fIchmod 777 pub\fP
|
||
|
|
\fB#\fP \fIcd bin\fP
|
||
|
|
\fB#\fP \fIcp /bin/sh /bin/ls .\fP
|
||
|
|
\fB#\fP \fIchmod 111 sh ls\fP
|
||
|
|
\fB#\fP \fIcd ../etc\fP
|
||
|
|
\fB#\fP \fIawk -F: '{$2="*";print$1":"$2":"$3":"$4":"$5":"$6":"}' < /etc/passwd > passwd\fP
|
||
|
|
\fB#\fP \fIawk -F: '{$2="*";print$1":"$2":"}' < /etc/group > group\fP
|
||
|
|
\fB#\fP \fIchmod 444 passwd group\fP
|
||
|
|
.DE
|
||
|
|
When local users wish to place files in the anonymous
|
||
|
|
area, they must be placed in a subdirectory. In the
|
||
|
|
setup here, the directory
|
||
|
|
.Pn ~ftp/pub
|
||
|
|
is used.
|
||
|
|
.PP
|
||
|
|
Aside from the problems of directory modes and such,
|
||
|
|
the ftp server may provide a loophole for interlopers
|
||
|
|
if certain user accounts are allowed.
|
||
|
|
The file
|
||
|
|
.Pn /etc/ftpusers
|
||
|
|
is checked on each connection.
|
||
|
|
If the requested user name is located in the file, the
|
||
|
|
request for service is denied. This file normally has
|
||
|
|
the following names on our systems.
|
||
|
|
.DS
|
||
|
|
uucp
|
||
|
|
root
|
||
|
|
.DE
|
||
|
|
Accounts without passwords need not be listed in this file as the ftp
|
||
|
|
server will refuse service to these users.
|
||
|
|
Accounts with nonstandard shells (any not listed in
|
||
|
|
.Pn /etc/shells )
|
||
|
|
will also be denied access via ftp.
|