ユーザ名とパスワードで BASE64エンコード

% echo -n 'username:password' | base64 -e

% echo -n 'username:password' | openssl enc -e -base64

% echo -n 'username:password' | nkf -MB

% echo -n 'username:password' | perl -MMIME::Base64 -ne 'print encode_base64($_)'

telnet で接続

% telnet hostname 80
GET /secret/index.html HTTP/1.0
Host: hostname:80
Authorization: Basic XXXXXXXXXXXX(BASE64エンコード)

Reference