For salt see: https://github.com/NagVis/nagvis/blob/51051b851b1b9981b51db81818700015735900a5/share/server/core/defines/global.php#L182
NAGVIS_SALT=42371010993337eeebe65383f731080da0f9f035
echo -n "${NAGVIS_SALT}mypassword" | sha1sum -
sqlite3 auth.db
To reset a password do this:
UPDATE users SET password '<generated hash>' WHERE name = 'username',
To create a new user, insert a user with its password hash and assign a role.
INSERT INTO users (name, password) VALUES ('myadmin', '<generated hash>');
SELECT * FROM users where name = 'myadmin';
INSERT INTO users2roles VALUES (15, 1); -- userId and roleId