SSH Key-Based Authentication on webMethods Active Transfer

Yet another security-related blog post on webMethods!

webMethods Active Transfer has got many cool MFT features and this post's topic is one of them. SSH key-based authentication is considered as one of the important aspects of client authentication to servers compared to the password-based authentication, even if the passwords are set up as very complex. Many of us do this every day while connecting to Unix/Linux-based servers via SSH clients like Putty/Mobaxterm/Filezilla/WinSCP, etc... Now, imagine, what if the process needs to be carried out on webMethods? Host systems like Unix/ Linux/ Windows will have no idea about these users as they are specific to an application server and reside inside them. So how does one add these app users under .ssh/authorised_keys, (which we can usually only do for system users)?

This is where Java-based security comes in for apps that run on the JVM. Java security modules allow us to achieve this but with a lot of effort and understanding of core security principles. webMethods Active Transfer allows us to enable this type of authentication with minimum effort.

Steps to Enable SSH Key-Based Authentication for a User

1. Login to MWS Admin Console and Navigate to Administration -> Integration -> Managed File Transfer -> User Management -> Users.
2. Search for the user on whose SSH public key authentication is to be enabled and select that user.
3. Once the user details are loaded, click on the "Restrictions" tab.
4. In the "Authentication and Login" section, click on the '+' button beside "Paths to Trusted Public SSH Key Files."
5. Enter the path where the user's public key is placed on the server.
6. Click on the "Save" button.

You are almost set and good to go. The reason I said "almost" set is because there are still some checks to be done before you go and try this out. You need to check/set the security levels you need or your customer demands at the SFTP connection level, which I cover in the next section "SSH Connection Authentication Levels."

Note: For simplicity purposes, I have explained the steps above to setup SSH keys at the User level. The same can be done at the Roles/Groups level, too, by following the same steps in their relevant section(s). In real time scenarios, it is advised to setup the SSH keys in the Roles/Groups level instead of the User level.

SSH Connection Authentication Levels

There are four kinds of possible combinations that can be set for SSH authentication. These combinations are tuned using two settings that can be found in below path.

Administration -> Integration -> Managed File Transfer -> Server Management -> Ports tab -> select the SFTP port on which clients will connect -> Go to the Advanced Tab -> SSH - Connection Settings

• Require Password Authentication
• Require Public Key Authentication

Basic Level - In this level, you will leave both the above options unchecked. This means clients can connect via the SFTP port either using their username and password or using their username and SSH key.

Intermediate Level - In this level, you will only need the "Require Password Authentication" option. This is the same as the basic level, but when a client tries to connect using an SSH key, the server prompts for an extra level of authentication to provide a password, too. So clients can connect using:

• Just a username or password (or)
• username + SSH key + password

Advanced Level - In this level, you will only need the "Require Public Key Authentication" option. This means we are enforcing a rule that SSH key-based authentication is required. So clients can connect to the SFTP port via an SSH key only. Password-based authentication will not work.

Complex Level - In this level, you will check both the options, "Require Password Authentication" and "Require Public Key Authentication." This means we are enforcing a rule that SSH key-based authentication is required along with the password. So clients can connect to the SFTP port only via an SSH key-password combination. Simple username/password or SSH key authentications will not work.

That's it. After setting this stuff up, you are completely good to go and try this out from any SFTP client like WinSCP or FileZilla.

#Happy_Coding #Happy_Integration!