EndRun RTM3204, User Manual

Page: 55 / 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
In the interest of conserving scarce system memory resources, only the secure shell server daemon,
sshd
and the secure copy utility,
scp
, are implemented in the RTM3204/Tycho. This means that
users on remote hosts may log in to the RTM3204/Tycho via an
ssh
client, but users logged in on
the RTM3204/Tycho are unable to log in to a remote host via
ssh
. Since
scp
runs in concert with an
ssh
client, the same limitations exist for its use, i.e. users on remote hosts may transfer files to and
from the RTM3204/Tycho via
scp
over
ssh
but users logged in on the RTM3204/Tycho are unable
to transfer files to and from a remote host via
scp
over
ssh
.
The factory configuration contains a complete set of security keys for both SSH1 and SSH2 versions
of the protocol. RSA keys are supported by both versions, and DSA keys are supported when using
the SSH2 version.
In addition, the RTM3204 is factory configured with a set of public keys for passwordless, public
key authentication of the root user. To use this capability, the corresponding set of private keys for
each of the two SSH versions are provided in the /boot/root directory of the RTM3204/Tycho. Three
files contain these keys:
identity
(SSH1),
id_rsa
(SSH2) and
id_dsa
(SSH2). These must be copied
to the user’s ~/.ssh directory on their remote computer. (Be careful to maintain the proper owner-
ship and access permissions by using
cp -p
when copying the files. They MUST be readable only
by root .) The corresponding public keys are by factory default resident in the /root/.ssh directory of
the RTM3204/Tycho. Two files contain these keys:
authorized_keys
(SSH1) and
authorized_keys2
(SSH2).
Since the provided private keys are not passphrase protected, the user should create a new set of
keys after verifying operation with the factory default key sets. After creating the new keys, the
public keys should be copied to the
/boot/root/.ssh
directory of the RTM3204/Tycho. At boot time,
the RTM3204/Tycho will copy these to the actual /root/.ssh directory of the system ramdisk, thereby
replacing the factory default set of public keys.
Advanced users wishing to modify the configuration of the
sshd
daemon should edit the /etc/sshd_
config
file and then copy it to the
/boot/etc
directory of the RTM3204/Tycho. Be careful to maintain
the proper ownership and access permissions by using
cp -p
when copying the file. At boot time,
it will be copied to the
/etc
directory of the system ramdisk, thereby replacing the factory default
configuration file.