Global config file of ssh daemon are in directory "/etc/ssh/", and this file named "ssh_config". I.e. full path "/etc/ssh/ssh_config".
The ssh program on a host receives its configuration from either the command line or from local configuration file "~/.ssh/config" and global "/etc/ssh/ssh_config".
Command-line options take precedence over configuration files. The user-specific configuration file "~/.ssh/config" is used next. Finally, the global "/etc/ssh/ssh_config" file is used. The first obtained value for each configuration parameter will be used.