/etc/issue are used to display a banner (e.g. welcome line/ warning..) to SSH users before the login prompt:
/etc/issue.net is shown to the users who connect from the network.
/etc/issue is shown to both local users and network users unless
/etc/issue.net is present and configured.
Also, to configure them to be displayed when you login via SSH, you need to uncomment
#Banner and specify the desired filename at
/etc/issue.net is the historical location for pre-login banners for network logins using protocols like
rlogin. Some Unix vendors had a version of
rlogind that used
/etc/issue for network logins too; others made it configurable like
sshd does now.