5 ip security aaa

TRAINER: SAGAR | NetworkJourney.com | www.youtube.com/c/NetworkJourney | LinkedIN
CCNP ENTERPRISE 2020 LAB WORKBOOK|| TRAINER: SAGAR || WWW.YOUTUBE.COM/C/NETWORKJOURNEY
TOPICS COVERED:
IP SERVICES
- AAA [ AUTHENTICATION, AUTHORIZATION, ACCOUTING ]
- ACCESS-LIST [ ACL ]

AAA [ AUTHENTICATION, AUTHORIZATION, ACCOUTING ]
AAA
Authentication, authorization and accounting (AAA) is a system for tracking user activities on an IP-
based network and controlling their access to network resources. AAA is often being implemented as a
dedicated server.
This term is also referred to as the AAA Protocol.
1. Authentication refers to unique identifying information from each system user, generally in the form
of a username and password. System administrators monitor and add or delete authorized users
from the system.
2. Authorization refers to the process of adding or denying individual user access to a computer
network and its resources. Users may be given different authorization levels that limit their access to
the network and associated resources.
3. Accounting refers to the record-keeping and tracking of user activities on a computer network. For a
given time period this may include, but is not limited to, real-time accounting of time spent accessing
the network, the network services employed or accessed, capacity and trend analysis, network cost
allocations, billing data, login data for user authentication and authorization, and the data or data
amount accessed or transferred.
RADIUS vs TACACS+
TACACS+ RADIUS
TACACS+ uses TCP RADIUS uses UDP
TACACS+ uses TCP port 49 Uses port 1812/1645 for authenticating
Uses port 1813/1646 for accounting
TACACS+ encrypts the entire communication RADIUS encrypts passwords only
TACACS+ treats Authentication, Authorization and
Accountability differently
RADIUS combines authentication and
authorization
TACACS+ is Cisco proprietary protocol RADIUS is an open protocol
TACACS+ is a heavy-weight protocol consuming
more resources
RADIUS is a light-weight protocol consuming less
resources
TACACS+ supports 15 privilege levels RADIUS is limited to privilege mode
Mainly used for Device administration Mainly used for Network access
Note: RADIUS has been officially assigned UDP ports 1812 for RADIUS authentication and 1813 for
RADIUS accounting by the Internet Assigned Numbers Authority (IANA). However, prior to IANA allocation
of ports 1812 and 1813, ports 1645 and 1646 (authentication and accounting, respectively) were used
unofficially, and became the default ports assigned by many RADIUS client/server implementations at
that time. The tradition of using 1645 and 1646 for backwards compatibility continues to this day. For this
reason, many RADIUS server implementations monitor both sets of UDP ports for RADIUS requests.
The early deployment of RADIUS was done using UDP port number 1645, which conflicts with the
"datametrics" service. The officially assigned port number for RADIUS is 1812 (in 2000).
The early deployment of RADIUS Accounting was done using UDP port number 1646, which conflicts
with the "sa-msg-port" service. The officially assigned port number for RADIUS Accounting is 1813
(in 2000).

GNS3
CLI Commands: (TACACS+)
Switch (config)#
interface vlan 1
no switchport
ip add 192.168.1.101 255.255.255.0
exit
Switch (config)#username admin pri 15 password cisco
Switch (config)#enable password cisco
Switch (config)#aaa new-model
Switch (config)#aaa group server tacacs+ gns3group
Switch (config-sg-tacacs+)#server name container
Switch (config-sg-tacacs+)#exit
Switch (config)#tacacs server container
Switch (config-server-tacacs)#address ipv4 192.168.1.200
Switch (config-server-tacacs)#key gns3
Switch (config-server-tacacs)#exit
Switch (config)# aaa authentication login default group gns3group local → TACACS+
Switch (config)#aaa authentication enable default enable → enable password cisco
Verifications:
-------------------
debug aaa authentication
debug tacacs

Do a self telnet 192.168.29.102
Username: gns3
Password: gns3
Or
Username: readonly
Password: gns3
Show users
show line
cd /etc/tacacs+
cat tac_plus.conf
root@AAA-1:~# service tacacs_plus start/stop
CLI Commands: (RADIUS)
Switch(config)#username admin pri 15 password cisco
Switch(config)#aaa new-model
Switch(config)#enable password cisco

Switch(config)#aaa group server radius gns3group2
Switch(config-sg-radius)#server name radius1
Switch(config-sg-radius)#exit
Switch(config)# radius server radius1
Switch(config-radius-server)# address ipv4 192.168.29.221 auth-port 1812 acct-port 1813
Switch(config-radius-server)#key gns3
Switch(config)# aaa authentication login default group gns3group2 local → Radius
Switch(config)#aaa authentication enable default enable → enable password cisco
Note: RADIUS has been officially assigned UDP ports 1812 for RADIUS authentication and 1813 for
RADIUS accounting by the Internet Assigned Numbers Authority (IANA). However, prior to IANA allocation
of ports 1812 and 1813, ports 1645 and 1646 (authentication and accounting, respectively) were used
unofficially, and became the default ports assigned by many RADIUS client/server implementations at
that time. The tradition of using 1645 and 1646 for backwards compatibility continues to this day. For this
reason, many RADIUS server implementations monitor both sets of UDP ports for RADIUS requests.
Verifications:
-------------------
debug aaa authentication
debug radius
Do a self telnet 192.168.29.102
Username: bob or alice
Password: gns3
Show users
show line
root@AAA-1:~# cat /etc/freeradius/3.0/users
service freeradius start/stop

ACCESS-LIST [ ACL ]
Defining an ACL
An ACL is a router configuration script (a list of statements) that controls whether a router
permits or denies packets to pass, based on criteria in the packet header. To determine whether
a packet is permitted or denied, it is tested against the ACL statements in sequential order.
When a statement matches, no more statements are evaluated; the packet is either permitted
or denied. There is an implicit deny any statement at the end of the ACL. If a packet does not
match any of the statements in the ACL, it is dropped.
Types of ACLs
ACLs can be configured to filter any type of protocol traffic, including other network layer
protocols such as AppleTalk and IPX. For the CCNA exam, we focus on IPv4 and IPv6 ACLs,
which come in the following types:
1. Standard IPv4 ACLs: Filter traffic based on source address only (all services are blocked)
2. Extended IPv4 and IPv6 ACLs: Can filter traffic based on source and destination address,
specific protocols, and source and destination TCP and UDP ports
Two ways to Identify Standard or Extended ACL:
1. Numbered IPv4 ACLs: Use a number for identification
2. Named IPv4 and IPv6 ACLs: Use a descriptive name or number for identification
Named ACLs must be used with some types of Cisco IOS configurations, including IPv6 ACLs.
However, they provide two basic benefits for standard and extended IPv4 ACLs:
➢ By using a descriptive name (such as BLOCK-HTTP), a network administrator can more
quickly determine the purpose of an ACL. This is particularly helpful in larger networks,
where a router can have many ACLs with hundreds of statements.
➢ Both numbered and named ACLs can be configured for standard as well as extended ACL
implementations.

ACL IDENTIFICATIONS:
Cisco IOS Software Release 12.3 introduced IP access list entry sequence numbering for both
numbered and named ACLs. IP access list entry sequence numbering provides the following
benefits:
▪ You can edit the order of ACL statements.
▪ You can remove individual statements from an ACL.
▪ You can use the sequence number to insert new statements into the middle of the ACL.
▪ Sequence numbers are automatically added to the ACL if they are not entered explicitly at
the time the ACL is created.

Access List Rules
The following rules apply to access lists:
1. Only one access list per interface, per protocol, and per direction is allowed.
2. An access list must contain at least one permit statement or all packets are denied entry into the
network.
3. After a match is found, no more criteria statements are checked.
4. If an access list is referenced by a name, but the access list does not exist, all packets pass. An
interface or command with an empty access list applied to it permits all traffic into the network.
5. Standard access lists and extended access lists cannot have the same name.
6. Inbound access lists process packets before the packets are routed to an outbound interface.
Inbound access lists that have filtering criteria that deny packet access to a network saves the
overhead of routing lookup.
7. Outbound access lists process packets before they leave the device. Incoming packets are routed
to the outbound interface and then processed by the outbound access list. For outbound access lists,
when you configure a permit statement, packets are sent to the output buffer, and when you
configure a deny statement, packets are discarded.
8. An access list can control traffic arriving at a device or leaving a device, but not traffic originating
at a device.
TYPES OF ACLS:

1. Standard ACLs
Standard ACLs are the oldest type of ACL. They date back to as early as Cisco IOS Software Release
8.3. Standard ACLs control traffic by the comparison of the source address of the IP packets to the
addresses configured in the ACL.
access-list access-list-number {permit|deny} {host|source source-wildcard|any}
NUMBERED STANDARD ACL:
interface Ethernet0/0
ip address 10.1.1.1 255.255.255.0
ip access-group 1 in
exit
access-list 1 permit 10.1.1.0 0.0.0.255
NAMED STANDARD ACL:
R1(config)# ip access-list standard blockacl
R1(config-std-nacl)# deny 172.16.40.0 0.0.0.255
R1(config-std-nacl)# permit any
R1(config)# int fa0/1
R1(config-if)# ip access-group blockacl out
2. Extended Access Lists
Extended access lists are good for blocking traffic anywhere. Extended access lists test source and
destination addresses and other IP packet data, such as protocols, TCP or UDP port numbers, type of
service (ToS), precedence, TCP flags, and IP options. Extended access lists can also provide
capabilities that standard access lists cannot, such as the following:
• Filtering IP Options
• Filtering TCP flags
• Filtering noninitial fragments of packets
• Time-based entries
NAMED EXTENDED ACL:
R1(config)# ip access-list extended blockacl
R1(config-ext-nacl)# deny tcp 172.16.40.0 0.0.0.255 172.16.50.0 0.0.0.255 eq 21
R1(config-ext-nacl)# deny tcp any 172.16.50.0 0.0.0.255 eq 23
R1(config-ext-nacl)# permit ip any any

R1(config-if)# ip access-group blockacl out
NUMBERED EXTENDED ACL:
R1(config)# access-list 110
deny tcp 172.16.40.0 0.0.0.255 172.16.50.0 0.0.0.255 eq 21
R1(config)# access-list 110 permit ip any any
R1(config-if)# ip access-group 110 out

5 ip security aaa

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