AdvLinux for i486SX Manual
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to log in the server on another computer.
5.3. Prevent the system from responding to the
ping command
This is a good way to protect the system. To prevent the system from
responding to the ping command, the following command can be used:
#echo 1 > /proc/sys/net/ipv4/icmp_echo_ignore_all
To restore the system to respond the ping command, use the following
command:
#echo 0 > /proc/sys/net/ipv4/icmp_echo_ignore_all
5.4. Prohibit the keyboard closing command
Control-Alt-Delete
Annotate the following line in the file accessed by /etc/inittab:
ca::ctrlaltdel:/sbin/shutdown -t3 -r now
Then change it to:
#ca::ctrlaltdel:/sbin/shutdown -t3 -r now
Enter the following command in order to perform the change:
# /sbin/init q
5.5. Make the root file system read-only
Advantech Embedded Linux for i486SX can mount root file system with
read-only or read-write mode according to parameter in grub
configuration file. When grub is loading during system is booting,
press the direction key and an interface providing two boot choices
for the user to select. The writable mode is set as the default. In
order to enhance its stability, the user had better to select the
read-only mode.
