In custom object i have credential of another org contain username and password , login button as quick action too , i have issue that username and password is visible in url
so its not good so i tried to go through the token based login salesforce ? as access_token which is generated by client id and client security ,created a connected app for postman to access
used this and get access code to use in postman , tried to login salesforce using access token which i get by send oauth2 get request in postman and got instance url and signature and access token by using access token i tried like this
http://[instance].salesforce.com/secur/frontdoor.jsp?sid=[access token]
open new tab and try to login by the above link. it redirect to login page of salesforce and ask again username and pass for it