EndRun RTM3204, Руководство пользователя

Страница: 54 / 66

R T M 3 2 0 4 G P S T i m i n g M o d u l e U s e r M a n u a l 44
A P P E N D I X D
45 R T M 3 2 0 4 G P S T i m i n g M o d u l e U s e r M a n u a l
S E C U R I T Y
The last two topics are supported on the RTM3204 by a pair of shell scripts which ease configuration
for the inexperienced user of Unix-like operating systems. These are
accessconfig
and
inetd-
config
.
accessconfig
modifies two files which are used by
tcpd
and the standalone daemon,
snmpd
to
determine whether or not to grant access to a requesting host: /etc/hosts.allow and /etc/hosts/deny .
These two files may contain configuration information for a number of protocol servers, but in the
RTM3204/Tycho only access control to the protocol server daemons
in.telnetd
,
sshd
and
snmpd
is configured.
As shipped from the factory, these two files are empty. When the user runs
accessconfig
, these
lines are added to the
/etc/hosts.deny
file:
in.telnetd: ALL
sshd: ALL
snmpd: ALL
This tells
tcpd
to deny access to
in.telnetd
and
sshd
to all hosts not listed in the /etc/hosts.allow
file. The
snmpd
daemon also parses this file itself prior to granting access to a requesting host. Then
the user is prompted to enter a list of hosts that will be granted access to
in.telnetd
,
sshd
and
snmpd
. These appear in the
/etc/hosts.allow
as lines like this:
in.telnetd: 192.168.1.2, 192.168.1.3
sshd: 192.168.1.2, 192.168.1.3
snmpd: 192.168.1.2, 192.l68.1.3
This simple shell script handles the needs of most users, however the syntax of these two files sup-
ports elaborate configuration possibilities which are beyond the capabilites of this simple shell script.
Advanced users who need these capabilities will need to edit these two files directly and then copy
them to the /boot/etc directory. (A very compact editor with WordStar command keystrokes is avail-
able on the system for this purpose:
edit
. If you start
edit
without giving it a file name to open,
it will display its help screen, showing the supported keystrokes.) Be careful to maintain the proper
ownership and access permissions by using
cp -p
when copying the files.
inetdconfig
modifies the /etc/inetd.conf file which is read by
inetd
to start-up various protocol
server daemons when requests from remote hosts are received. Currently, four servers are configu-
rable via
inetdconfig
: TIME and DAYTIME, whose daemons are contained within the
inetd
daemon itself, and
in.telnetd
and
sshd
. Any one or all of these may be enabled or disabled for
start-up.
OpenSSH
The secure shell protocol server running in the RTM3204/Tycho is based on the portable OpenSSH
for Linux. As such it supports both SSH1 and SSH2 protocol versions. For more information about
this protocol and to obtain client software, refer to the OpenSSH website: http://www.openssh.com.
An excellent book which describes operation and configuration of the various SSH implementations,
including OpenSSH is available from O’Reilley & Associates:
SSH, The Secure Shell , Barrett & Silverman, O’Reilley & Associates, 2001