Understanding the 'rpcclient' Command (with examples)

The ‘rpcclient’ tool is a versatile command-line utility that is part of the Samba suite, providing an interface to interact with Windows RPC (Remote Procedure Call) services. It is commonly used for administrative tasks on Windows networks within a domain. By using ‘rpcclient’, system administrators can perform a variety of actions such as managing users, querying domain information, and executing remote commands. This article outlines several practical uses of the ‘rpcclient’ command, complete with examples to demonstrate its functionality.

Use Case 1: Connect to a Remote Host

Code:

rpcclient --user domain\username%password ip

Motivation:

One of the fundamental operations needed in network administration is the ability to connect to a remote host to manage or query it. With ‘rpcclient’, administrators can establish a connection using the domain credentials, allowing them to perform a series of remote tasks without physically being at the host machine. This capability is crucial for maintaining large networks where physical access to every host can be impractical.

Explanation:

• rpcclient: This is the command being used from the Samba suite to interact with RPC services on a remote machine.
• --user domain\username%password: Specifies the user credentials. domain\username indicates the user’s domain and username, while %password is used to provide the user’s password.
• ip: The IP address of the remote host you wish to connect to.

Example Output:

rpcclient $> 

This indicates a successful connection to the remote host, where you can now enter further commands.

Use Case 2: Connect to a Remote Host on a Domain Without a Password

Code:

rpcclient --user username --workgroup domain --no-pass ip

Motivation:

In certain scenarios, an administrator may need to connect to a remote host without the use of a password, leveraging other forms of authentication such as Kerberos. This use case is valid in environments where passwordless operations are securely configured, aiding in seamless integration and speedier connections for scripted or automated routines.

Explanation:

• rpcclient: The command from the Samba utilities.
• --user username: The username used for authentication.
• --workgroup domain: The workgroup or domain in which the operation is being performed.
• --no-pass: Indicates that no password will be provided or prompted.
• ip: The IP address of the target remote host.

Example Output:

rpcclient $> 

A prompt similar to this suggests that you have successfully connected without a password.

Use Case 3: Connect to a Remote Host, Passing the Password Hash

Code:

rpcclient --user domain\username --pw-nt-hash ip

Motivation:

For enhanced security, administrators might use password hashes instead of plain text passwords during authentication. This method reduces the risk of exposing credentials over a network and is particularly useful in environments following stringent security protocols.

Explanation:

• rpcclient: The Samba tool being used.
• --user domain\username: User identifier, combining the domain and username.
• --pw-nt-hash: Specifies that the provided password is in NT hash format.
• ip: The target host’s IP address.

Example Output:

rpcclient $> 

This result shows a successful connection made using a hashed password.

Use Case 4: Execute Shell Commands on a Remote Host

Code:

rpcclient --user domain\username%password --command semicolon_separated_commands ip

Motivation:

A powerful feature of ‘rpcclient’ is its ability to execute commands on remote machines. This is particularly useful for system administrators who need to carry out administrative scripts or tasks remotely, thus saving time and facilitating better network management.

Explanation:

• rpcclient: The tool used for executing RPC commands.
• --user domain\username%password: Specifies the credential format for accessing the host.
• --command semicolon_separated_commands: The commands you wish to run on the remote machine, separated by semicolons.
• ip: The IP address of the remote machine to execute commands on.

Example Output:

rpcclient $> Command executed successfully

The output confirms that the remote commands were carried out effectively.

Use Case 5: Display Domain Users

Code:

rpcclient $> enumdomusers

Motivation:

Listing all users in a domain is a common administrative task. It helps in audits, user management, and security assessments. By knowing who has access to a domain and what roles they have, administrators can better control and manage network resources.

Explanation:

• rpcclient $>: Indicates that you are issuing a command within the rpcclient interface.
• enumdomusers: The command to enumerate all domain users.

Example Output:

user:[Administrator] rid:[0x1f4]
user:[Guest] rid:[0x1f5]
user:[test_user] rid:[0x3e9]

The output provides a list of users with their associated RIDs (Relative Identifiers).

Use Case 6: Display Privileges

Code:

rpcclient $> enumprivs

Motivation:

To maintain and audit domain security, it is essential for administrators to understand the privileges granted within their networks. Listing these privileges can reveal potential vulnerabilities or misconfigurations that need addressing.

Explanation:

• rpcclient $>: Command prompt for entering rpcclient commands.
• enumprivs: Enumerates the privileges available on the domain.

Example Output:

privilege:[SeCreateTokenPrivilege] description:[Create a token object]
privilege:[SeTrustedCredManAccessPrivilege] description:[Access Credential Manager as a trusted caller]

The output enumerates different privileges along with their descriptions.

Use Case 7: Display Information About a Specific User

Code:

rpcclient $> queryuser username|rid

Motivation:

For managing users effectively, administrators often need detailed information about specific accounts. This data can include user status, profile details, last login times, etc., and it supports tasks like troubleshooting account issues and performing user audits.

Explanation:

• rpcclient $>: Command environment for issuing rpcclient commands.
• queryuser username|rid: Queries detailed information about a specified user, either by username or RID.

Example Output:

User Name   :   test_user
Full Name   :   Test User
User ID     :   0x3e9
Logon Hours :   FFFFFFFF FFFFFFFF FFFFFFFF

The output provides comprehensive details on the specified user account.

Use Case 8: Create a New User in the Domain

Code:

rpcclient $> createdomuser username

Motivation:

Adding new users to a domain is a routine task for administrators as organizations grow and new employees join. Using ‘rpcclient’, this task can be streamlined and automated, ensuring seamless integration into the network’s existing security and user management systems.

Explanation:

• rpcclient $>: The command interface for ‘rpcclient’.
• createdomuser username: Command to create a new user in the domain with the specified username.

Example Output:

SAM Create Domain User
Domain User jsmith created

The output indicates that the new domain user has been successfully created.

Conclusion:

The ‘rpcclient’ command from the Samba suite is a powerful tool for network administrators, enabling seamless interactions with Windows networks for tasks ranging from user management to executing remote commands. By mastering these use cases, administrators can efficiently manage complex domain environments and ensure robust network security and performance.