I’ll admit to not having performed an intensive verification. Nonetheless, I’d nonetheless guess cash that AAA/RBAC providers are extra continuously talked about on Cisco certification blueprints than every other networking subject. From the CCNA to the Knowledgeable stage, you’ll discover AAA, TACACS+, RADIUS, and RBAC listed on the examination matters.
Here’s a handful of examples in case you’d wish to test it out your self:
- 200-301 CCNA
- 2.8 Describe AP and WLC administration entry connections (Telnet, SSH, HTTP, HTTPS, console, and TACACS+/RADIUS)
- 5.8 Differentiate authentication, authorization, and accounting ideas
- 350-401 ENCOR
- 5.1 Configure and confirm gadget entry management
- 300-410 ENARSI
- 3.1 Troubleshoot gadget safety utilizing IOS AAA (TACACS+, RADIUS, native database)
- 300-430 ENWLSI
- 8.1 Implement gadget entry controls (together with RADIUS and TACACS+)
- 350-701 SCOR
- 2.7 Configure AAA for gadget and community entry comparable to TACACS+ and RADIUS
- 300-715 SISE
- 7.0 Community Entry Machine Administration
- 350-601 DCCOR
- 5.xa Apply community|compute|storage safety – AAA and RBAC
- 300-615 DCIT
- 5.xb Troubleshooting community|compute|storage safety – AAA and RBAC
- 350-501 SPCOR
- 1.6b Describe administration airplane safety – AAA and TACACS
- 300-540 SPCNI
- 4.1e Implement infrastructure safety – TACACS
OMG. That’s 10 totally different certifications from Affiliate to Skilled the place these matters present up. You’ll additionally discover them on Knowledgeable-level exams, such because the Enterprise Infrastructure, Enterprise Wi-fi, Safety, Service Supplier, and Information Heart labs. (If anybody on the market can discover one other subject with as broad a protection, please let me know within the feedback. I’d like to know what I’ve missed to date.)
Go to the Cisco Studying Community to view the examination matters for all Cisco certification exams. View examination matters
Okay… it’s undoubtedly necessary… however what is AAA?
AAA is a crucial subject, however it’s one which even long-time community engineers might not totally perceive. So earlier than we see it in motion, how a couple of fast overview of what the “triple A’s” imply?
Within the “AAA in Motion!” comedian, Carl experiences your complete AAA course of:
- The primary “A” stands for Authentication. We see this represented when Carl is prompted to confirm his id earlier than he’s allowed to make a change to the community.
- The second “A” stands for Authorization. Even after the community verifies Carl’s id, he has to test whether or not he has the correct(s) to make this alteration, based mostly on which rights he has been granted on the community.
- And the third and remaining “A” stands for Accounting, which Carl sees in motion when the community logs the change he makes to the community.
TACACS comes into the image to assist the centralized administration of customers, roles, and logs (authentication, authorization, and accounting). Whereas every community gadget might be domestically configured to deal with AAA, this doesn’t scale effectively for enterprises. A greater resolution is for every community gadget to speak with a central “server” for these actions. TACACS is a protocol that community gadgets and servers use to speak and deal with every of the “A’s.” A “TACACS Server” is a software program utility that helps the TACACS protocol.
Can we get to the Exploration, already?!
Now that we perceive the essential function that AAA performs in a community (and that it’s an important subject throughout many certifications), I’d like to indicate you the way to examine and put together for it utilizing my favourite community simulation/virtualization device: Cisco Modeling Labs (CML). As a result of I’m all about sharing my exploration actions, I posted a few CML topology recordsdata on GitHub within the CML-community repository beneath Cisco DevNet.
You’ll see that one CML topology contains simply an IOL router, whereas one other provides a Nexus 9000v swap to cowl information middle platforms as effectively. So, after you’ve learn this weblog submit, undoubtedly obtain the topologies and discover them your self.
The right way to run a TACACS Server in Cisco Modeling Labs
Earlier than you’ll be able to configure TACACS on a swap or router, you could have a TACACS server accessible within the community. A typical TACACS server for a manufacturing community is Cisco ISE, a full “id providers engine” for gadget administration, community entry, wi-fi safety, VPN entry, and extra.
Cisco ISE is a crucial product and subject for community engineers. In actual fact, we now have a certification examination devoted to it. And when you can add Cisco ISE to a CML node library utilizing the node definition accessible on the CML-Group, working a full ISE server within the topology can really feel overkill when the main target is simply on configuring TACACS for gadget administration.
Fortunately, there are light-weight alternate options. My go-to possibility is the open-source “tac_plus” utility that has been accessible for a few years. Tac_plus is a primary Linux utility that may be downloaded and put in on most Linux distributions. Whereas energetic improvement of the challenge appears to have stalled, it really works nice and continues to be a wonderful possibility for instances comparable to this.
If you happen to take a look at the picture of the CML topology, you’ll see “aaa-server” on the left-hand facet of the diagram. It is a normal Ubuntu node from the CML reference platforms, with a beginning configuration setup to put in tac_plus and configure it as a primary TACACS server. Be at liberty to go and take a look at the configuration within the topology file for full particulars, however listed here are the fundamentals of what I did to construct my TACACS server:
- Set up the necessities to obtain and set up the tac_plus utility from supply code.
- Create the “tac_plus.conf” configuration file to specify the TACACS secret key, customers, and roles/privilege ranges for each IOS and NX-OS platforms.
- Create a “tac_plus.service” file to setup tac_plus as a service.
- Obtain, extract, set up, and begin the tac_plus server.
With the set up and configuration of the aaa-server a part of the bottom CML topology file, tac_plus will likely be working and able to take requests as quickly because the lab is began.
cisco@aaa-server:~$ systemctl standing tac_plus
● tac_plus.service - tac_plus Service
Loaded: loaded (/and many others/systemd/system/tac_plus.service; enabled; vendor pres>
Energetic: energetic (working) since Mon 2024-10-14 19:16:37 UTC; 2s in the past
Most important PID: 5982 (tac_plus)
Duties: 1 (restrict: 2310)
Reminiscence: 416.0K
CPU: 2ms
CGroup: /system.slice/tac_plus.service
└─5982 /tacacs/sbin/tac_plus -G -C /and many others/tacacs/tac_plus.conf -d 8 >
Oct 14 19:16:37 aaa-server systemd[1]: Began tac_plus Service.
Oct 14 19:16:37 aaa-server tac_plus[5982]: Studying config
Oct 14 19:16:37 aaa-server tac_plus[5982]: Model F4.0.4.28 Initialized 1
Oct 14 19:16:37 aaa-server tac_plus[5982]: tac_plus server F4.0.4.28 beginning
Oct 14 19:16:37 aaa-server tac_plus[5982]: socket FD 4 AF 2
Oct 14 19:16:37 aaa-server tac_plus[5982]: socket FD 5 AF 10
Oct 14 19:16:37 aaa-server tac_plus[5982]: uid=0 euid=0 gid=0 egid=0 s=11063704>
The right way to allow AAA and TACACS on a Cisco IOS Router
With our TACACS server up and operational, we will now configure our IOS router to make use of it. Earlier than configuring the TACACS server on IOS, we have to guarantee some primary “pre-work” is finished on our router. IOS has been round for years and has skilled many adjustments in how authentication and authorization are dealt with.
So, the very first thing we wish to do is make sure the “new mannequin” of AAA is enabled on our gadget:
aaa new-model
Subsequent, we wish to create an area consumer account that may entry and administer the gadget if the TACACS server turns into unreachable. You may additionally wish to use an area account for serial/console connections.
username cisco privilege 15 secret cisco
On this command, the username and password are each set to “cisco.” (Not essentially the most safe alternative, however that is only a lab.) The “privilege 15” a part of the command signifies that this consumer will likely be assigned an “administrator” function. Privilege 15 is the very best stage on an IOS gadget and permits the consumer to execute any and all instructions.
We’re able to configure and check TACACS now. However first, I bounce onto the console for the server and begin monitoring the logs. This fashion, I can test and confirm outcomes on the server facet in addition to on the shopper.
# On aaa-server journalctl -fu tac_plus # Output Oct 14 19:16:37 aaa-server systemd[1]: Began tac_plus Service. Oct 14 19:16:37 aaa-server tac_plus[5982]: Studying config Oct 14 19:16:37 aaa-server tac_plus[5982]: Model F4.0.4.28 Initialized 1 Oct 14 19:16:37 aaa-server tac_plus[5982]: tac_plus server F4.0.4.28 beginning Oct 14 19:16:37 aaa-server tac_plus[5982]: socket FD 4 AF 2 Oct 14 19:16:37 aaa-server tac_plus[5982]: socket FD 5 AF 10 Oct 14 19:16:37 aaa-server tac_plus[5982]: uid=0 euid=0 gid=0 egid=0 s=1106370448
Within the above command, the “-f” argument “follows” the log messages as they arrive in. And the “-u tac_plus” possibility limits the output to solely message from the tac_plus service.
Glorious. Now, again to the router to configure the tacacs server and add it to a gaggle of servers that the router can use for AAA service.
tacacs server aaa-server handle ipv4 192.168.0.10 key tacacs123 aaa group server tacacs+ AAA-TACACS server title aaa-server
I’m at all times a fan of testing that one thing will (or seemingly will) work earlier than continuing. Conveniently, IOS helps a “check aaa” command that we will use.
check aaa group AAA-TACACS iosadmin admin123 legacy # Output Making an attempt authentication check to server-group AAA-TACACS utilizing tacacs+ Person was efficiently authenticated.
That appears nice! And I can see the logs on “aaa-server” as effectively.
Oct 14 19:55:16 aaa-server tac_plus[6473]: join from 192.168.0.1 [192.168.0.1] Oct 14 19:55:17 aaa-server tac_plus[6473]: login question for 'iosadmin' port unknown-port from 192.168.0.1 accepted
With a robust sense of confidence, let’s full the AAA configuration for all three “A’s.”
! Authentication aaa authentication login default group AAA-TACACS native ! Authorization aaa authorization exec default group AAA-TACACS native aaa authorization console ! Accounting aaa accounting exec default start-stop group AAA-TACACS aaa accounting instructions 1 default start-stop group AAA-TACACS aaa accounting instructions 15 default start-stop group AAA-TACACS
Sustaining that robust sense of confidence, let’s see if it really works. Finish/exit on the router till it’s good to log again in.
ios01 con0 is now accessible Press RETURN to get began. Person Entry Verification Username:
Attempt to log into the router utilizing the TACACS credentials for the IOS gadget.
Person Entry Verification Username: iosadmin Password: ios01#
Success! Examine the logs on the server, and it’s best to see one thing like this:
Oct 14 20:05:03 aaa-server tac_plus[6492]: login question for 'iosadmin' port tty0 from 192.168.0.1 accepted Oct 14 20:05:03 aaa-server tac_plus[6493]: join from 192.168.0.1 [192.168.0.1] Oct 14 20:05:03 aaa-server tac_plus[6493]: Begin authorization request Oct 14 20:05:03 aaa-server tac_plus[6493]: do_author: consumer="iosadmin" Oct 14 20:05:03 aaa-server tac_plus[6493]: consumer 'iosadmin' discovered Oct 14 20:05:03 aaa-server tac_plus[6493]: exec authorization request for iosadmin Oct 14 20:05:03 aaa-server tac_plus[6493]: exec is explicitly permitted by line 6 Oct 14 20:05:03 aaa-server tac_plus[6493]: nas:service=shell (handed via) Oct 14 20:05:03 aaa-server tac_plus[6493]: nas:cmd* (handed via) Oct 14 20:05:03 aaa-server tac_plus[6493]: nas:absent, server:priv-lvl=15 -> add priv-lvl=15 (okay) Oct 14 20:05:03 aaa-server tac_plus[6493]: added 1 args Oct 14 20:05:03 aaa-server tac_plus[6493]: out_args[0] = service=shell enter copy discarded Oct 14 20:05:03 aaa-server tac_plus[6493]: out_args[1] = cmd* enter copy discarded Oct 14 20:05:03 aaa-server tac_plus[6493]: out_args[2] = priv-lvl=15 compacted to out_args[0] Oct 14 20:05:03 aaa-server tac_plus[6493]: 1 output args Oct 14 20:05:03 aaa-server tac_plus[6493]: authorization question for 'iosadmin' tty0 from 192.168.0.1 accepted Oct 14 20:05:03 aaa-server tac_plus[6494]: join from 192.168.0.1 [192.168.0.1]
I’ve coloured the server output to focus on the authentication and authorization logs individually, displaying that they honestly are two totally different phases.
However what concerning the remaining “A” for accounting? Press Cntr-C to cease following the service log and open up the “accounting log.”
tail -f /var/log/tac_plus.acct # Output Oct 14 20:05:03 192.168.0.1 iosadmin tty0 async begin task_id=12 timezone=UTC service=shell
It’s best to see a message just like the above displaying the “begin” of the session on the router. Return to the router and run “write mem” to save lots of the configuration adjustments to reminiscence. A brand new log message ought to present up within the accounting log:
Oct 14 20:10:11 192.168.0.1 iosadmin tty0 async cease task_id=13 timezone=UTC service=shell priv-lvl=15 cmd=write reminiscence
And now, exit the router to sign off. A brand new message ought to seem as effectively:
Oct 14 20:11:02 192.168.0.1 iosadmin tty0 async cease task_id=13 timezone=UTC service=shell disc-cause=1 disc-cause-ext=9 pre-session-time=6 elapsed_time=89 stop_time=1728936662
And BAM. All three “A’s” have been validated. Glorious work!
Hopefully, this weblog has gotten you excited to finish your individual exploration of AAA and TACACS. And, you might be in luck—the CML topology recordsdata that I discussed above (and can once more beneath) are there so that you can seize and use instantly. Inside them are lab guides that stroll by another necessary AAA matters, comparable to utilizing native accounts on the console/serial line for IOS and configuring TACACS on Nexus gadgets. Nonetheless, I encourage you to do some unbiased exploration and experiment with issues which might be not within the information:
What occurs in case you kind the incorrect username/password? What occurs if the configured “tacacs key” is incorrect? What occurs if the TACACS server is unreachable?
Understanding the affect of issues and failures is essential to a community engineer’s capacity to be comfy when one thing goes incorrect in “actual life.” It’s significantly better to interrupt issues within the lab than watch for manufacturing to have points. And there’s no higher device than Cisco Modeling Labs for that exploration.
My very own AAA exploration will proceed. On this weblog and lab, I solely scratched the floor of the subject and data wanted for various certifications. RADIUS servers can be utilized as a substitute of TACACS, and what about AAA for issues like VPN authentication, community entry with 802.1x, or different platforms like ASA firewalls?
There are such a lot of extra prospects for me to discover in later weblog posts. Would you wish to see extra on AAA from me? Let me know within the feedback.
Till subsequent time!
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