So I have been playing around with some vulnerable VMs (from the awesome vulnhub.com. Some of them have had ftp and ssh services running on them. So I have tried to make dictionary attacks against them.
First we need some dictionaries with passwords. Here is a great collection of dictionaries/password-lists
This is the basic syntax. So first we add the list with usernames. Then the list of passwords. Then the ip. Then we specify the port (-s) then the service (in this case ssh). -V is for verbose mode.
The -s is only needed if the service is on another port than the default.
hydra -L userlist.txt -P best1050.txt 192.168.1.103 -s 45061 ssh -V
The man page is really quite useful.