While installing a custom component the following error occur.
fsockopen(): unable to connect to :80 (php_network_getaddresses: getaddrinfo failed: Name or service not known)
It seems that the component tries to connect to an external server and your webhost doesn't allow connecting to a remote site.
I have seen a similar issue before, enter the database and look at the table
#__update_sites make sure there is no spaces or line breaks before or after the url for the server its looking at. This was a problem in SobiPro, but if one component has that issue it basically completely breaks the extension manager.
If you do not see spaces in any of the update_sites then this is probably not the issue.
Check whether you installing or getting files from remote server after your component installed or before install. if yes then check your url path is incorrect ..am sure your url may be incorrect