To Install DenyHosts a log-based intrusion prevention system on Ubuntu version 14.04 LTS server for sshd, enter:
$ sudo apt-get install denyhosts
Reading package lists... Done Building dependency tree Reading state information... Done The following NEW packages will be installed: denyhosts 0 upgraded, 1 newly installed, 0 to remove and 0 not upgraded. Need to get 56.5 kB of archives. After this operation, 294 kB of additional disk space will be used. Get:1 http://mirrors.linode.com/ubuntu xenial/universe amd64 denyhosts all 2.10-2 [56.5 kB] Fetched 56.5 kB in 0s (0 B/s) Selecting previously unselected package denyhosts. (Reading database ... 28856 files and directories currently installed.) Preparing to unpack .../denyhosts_2.10-2_all.deb ... Unpacking denyhosts (2.10-2) ... Processing triggers for man-db (2.7.5-1) ... Processing triggers for systemd (229-4ubuntu16) ... Processing triggers for ureadahead (0.100.0-19) ... Setting up denyhosts (2.10-2) ... Processing triggers for systemd (229-4ubuntu16) ... Processing triggers for ureadahead (0.100.0-19) ...