---
title: "Method: TACACS+"
slug: "method-tacacs"
updated: 2026-05-14T12:10:11Z
published: 2026-05-14T12:10:11Z
---

> ## Documentation Index
> Fetch the complete documentation index at: https://docs.zpesystems.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Method: TACACS+

## **Overview**

TACACS+ (Terminal Access Controller Access-Control System) is a protocol that handles authentication, authorization, and accounting (AAA) services. The following diagram shows a Nodegrid Serial Console Plus (NSCP) and the Ubuntu server executing a TACACS+ server.

![](https://cdn.document360.io/763c5fb1-b9af-4ccd-9ad6-cf28ae4cd5a3/Images/Documentation/tacacs.png)

| (1) and (4) | Endpoint accessing the Nodegrid device using HTTPS. |
| --- | --- |
| (2) and (3) | Nodegrid sends the login request to the TACACS+ server for authentication. The TACACS+ server evaluates the request and determines whether to grant access to the Nodegrid and assigns the appropriate privilege level. |

An example of Ubuntu server executing TACACAS+ configuration is as shown:

```plaintext
key = test

accounting file = /var/log/tac.acct

group = nadmin {
    service = raccess {
        prlv-lvl = 15
    }
}

group = admin {
    service = raccess {
        prlv-lvl = 15
    }
}

group = read {
    service = raccess {
        prlv-lvl = 1
    }
}

user = nadmin {
       service = raccess {
               group_name = "admin"
       }
}

user = user 1 {
     login = cleartext hello
      member = tadmin
}

user = user 2 {
     login = cleartext user 2
      member = read
}

user = guest{
     default service = permit
     login = des guE/.mlvd58eU
}
```

The three user groups defined are:

- nadmin will be assigned to the Nodegrid user group admin
- tadmin, with privilege 15 and user: user 1
- read, with privilege 1 and user: user 2

> [!NOTE]
> NOTE:
> 
> - Check the syntax of the tacacs configuration, by using the command sudo service tacacs_plus check.
> - Check the status of the tacacs+ server, by using the command systemctl status tacacs_plus (the status given should be in green color, in state "active").

## Nodegrid Configuration

### **Web UI:**

1. Log in to the Nodegrid Web UI.
2. Navigate to *Security:: Authentication:: Servers* and select the Method as **TACACS+**.
3. Enter **Accounting Server**.

> [!NOTE]
> NOTE:
> 
> The accounting server is optional, and in case no accounting server is available the setting can be left blank.

![](https://cdn.document360.io/763c5fb1-b9af-4ccd-9ad6-cf28ae4cd5a3/Images/Documentation/tacacs(1).png)

> [!NOTE]
> Note
> 
> The fields Remote Server and Accounting Server correspond to the IP address of the Ubuntu Server. The Service, "raccess" has to match the Tacacs+ server.
4. Select **Authorize users authenticated with ssh public key** checkbox.
5. Enter **TACACS+ Port** (default: 49).
6. On **Service** drop-down, select one (PPP, Shell, raccess) (default: raccess).
7. Enter and confirm the secret shared with the Tacacs+ server**.**
8. Enter **Timeout** (default: 2).
9. Enter **Retries** (default: 2).
10. On **TACACS+ Version** drop-down, select the appropriate TACACS+ Version.
11. Enter **Enforce Source IP** for AAA authentication (available in v5.8+).
12. Select **Enable User-Level attribute of Shell and raccess services association to local authorization group** checkbox (expands dialog with 15 User Levels). Per instruction, “Enter local authorization group name for each User Level.” ![](https://cdn.document360.io/763c5fb1-b9af-4ccd-9ad6-cf28ae4cd5a3/Images/Documentation/tacacs-user-level.png)

> [!NOTE]
> Note
> 
> In this example,
> 
> - the tacacs+ admin group "tadmin" (of privilege 15), to the local Nodegrid admin group "admin".
> 
> - the tacacs+ admin group "read" (of privilege 1), to the local Nodegrid user group "Operator"

The user added in the TACACS+ as user1 will be able to login as shown in the following figure.

![](https://cdn.document360.io/763c5fb1-b9af-4ccd-9ad6-cf28ae4cd5a3/Images/Documentation/user1.jpg)

### CLI Configuration

1. Log in as admin in the CLI and type the following commands:

```plaintext
[admin@nodegrid /]# add settings/authentication/servers/
[admin@nodegrid {servers}]# set fallback_if_denied_access=yes
[admin@nodegrid {servers}]# set method=tacacs+
[admin@nodegrid {servers}]# set remote_server=10.10.10.13
[admin@nodegrid {servers}]# set tacacs_plus_accounting_server=10.10.10.13
[admin@nodegrid {servers}]# set tacacs_plus_secret=secretkey
[admin@nodegrid {servers}]# set tacacs_plus_service=raccess 
[admin@nodegrid {servers}]# set tacacs_plus_retries=2
[admin@nodegrid {servers}]# set tacacs_plus_timeout=2
[admin@nodegrid {servers}]# set tacacs_plus_version = v1
[admin@nodegrid {servers}]# set tacacs_plus_enable_user-level = yes
[admin@nodegrid {servers}]# set tacacs_plus_user_level_1 = Operator
[admin@nodegrid {servers}]# set tacacs_plus_user_level_15 = admin
```
2. Type show command to confirm your configuration.

```plaintext
 [admin@nodegrid {servers}]# show
```
3. Save the configuration.

```plaintext
[admin@nodegrid {servers}]# commit
```
4. Type the set command and tap tab key twice to view all the available option for configuration.

```plaintext
[admin@nodegrid {servers}]# set
```

The TACACS+ server added to Nodegrid.

> [!NOTE]
> NOTE
> 
> Default authentication service is raccess ( can be changed as needed )
> 
> Default value for retries and timeout is 2 ( can be changed as needed )
> 
> Default port is 49

## Group level to be used in Nodegrid OS

In the Web UI and TACACS+, specify the group level to be used in the Nodegrid OS. You can configure your TACACS+ server to map two separate groups, each with the same privilege level, to two different groups on the Nodegrid OS.

1. Go to *Security :: Authentication :: Servers :: 1.*
2. Uncheck **Enable User-Level attribute of Shell and raccess services association to local authorization group**. ![](https://cdn.document360.io/763c5fb1-b9af-4ccd-9ad6-cf28ae4cd5a3/Images/Documentation/uncheck-user-level.png)
3. On the TACACS+, server, add the attribute group_name in the groups:
4. Go to *Security :: Authorization :: Network_Admin :: Remote Groups*, in the Nodegrid groups add these groups under Remote Group.