A more secure SSH configuration

ryan — Thu, 13 Mar 2008 03:25:49 +0000

Some easy ways to configure SSH to be a little more secure:

Edit /etc/ssh/sshd_config as root.

Change the port (default is 22)
Change “PermitRootLogin yes” to “PermitRootLogin no”
AddUser username
save and quit
restart the ssh server: sudo /etc/init.d/ssh restart

More info here:
http://ubuntu-tutorials.com/2007/02/14/what-you-ought-to-know-about-securing-ssh/

Check open ports

ryan — Thu, 13 Mar 2008 03:17:23 +0000

Are there any open ports that shouldn’t be open? Check with:

sudo netstat -tupl

Results in something like:


Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address    Foreign Address  State    PID/Program name
tcp        0      0 localhost:mysql  *:*              LISTEN  5077/mysqld
tcp        0      0 localhost:ipp    *:*              LISTEN  5001/cupsd
udp        0      0 *:32768          *:*                      5324/avahi-daemon:
udp        0      0 *:bootpc         *:*                      5875/dhclient
udp        0      0 *:mdns           *:*                      5324/avahi-daemon:

Kill the process that is using the port

kill (PID here)

List open files:

lsof -i

where the -i makes it list internet files.

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A more secure SSH configuration

Check open ports