Configure Intelligent Security using RADIUS for User Equipment to IP Address Correlation

Information such as the Subscriber ID (IMSI or SUPI) and the Equipment ID (IMEI or PEI) for User Equipment (UE) mobile devices are key identifiers for Security policy enforcement in mobile networks such as 5G and 4G/LTE networks. Mapping the IMSI or IMEI to subscriber or user IP addresses requires access to the signaling protocol traffic exchanges over the 3GPP interfaces; however, in some deployments, the 3GPP interfaces between network functions are not exposed.

Intelligent Security with RADIUS in 5G allows deployment of the firewall on the N6/SGi interface, which contains the RADIUS traffic for the management plane, and Internet Protocol traffic without outer GTP-U headers for the dataplane. The firewall inspects the RADIUS traffic to extract information for correlation with the user plane. This provides subscriber and equipment-level visibility, as well as consistent policy enforcement for vulnerabilities, malware, viruses, URLs, C2, and applications.

If you enable UEIP Correlation, the following options are not available in the same Mobile Network Protection Profile:

GTP-C
5G-C
Packet Forwarding Control Protocol (PFCP)

The following diagram represents a possible deployment for UE to IP address correlation for an N6 deployment with RADIUS.

When the UE attempts to connect with the network, the SMF exchanges authentication, authorization, and accounting messages with the DN-AAA server using RADIUS. The accounting message provides a record of the network services that the authenticated UE accesses. This message contains parameters, which include the user's ID and IPv4 or IPv6 address, that the application servers use to identify the user.

The firewall monitors the Accounting Start messages on UDP ports 1813 and 1646 and Interim Updates to map the UE to the IP address and adds the mapping to the UEIP correlation database on the firewall. The firewall also generates a log during IP address allocation.

When the firewall receives the RADIUS session end message, it removes the mapping from the correlation database on the firewall and creates a log.

Intelligent Security requires the following fields and Vendor-Specific Attributes (VSAs) in the RADIUS messages:

Framed-IP-Address(8):
<IPv4-address>
Framed-IPv6-Prefix(97):
<IPv6-prefix>
Called-Station-Id:
<APN>
Vendor-Specific(26): VSA: t=3GPP-IMSI(1):
<IMSI_value>
Vendor-Specific(26): VSA: t=3GPP-IMEISV(20):
<IMEI_value>
Vendor-Specific(26): VSA: t=3GPP-RAT-Type(21):
<RAT>

Enable GTP Security.
Log in to the firewall web interface.
Select
Device
Setup
Management
General Settings
then select
GTP Security
.
Click
OK
.
Commit
the change.
Select
Device
Setup
Operations
and
Reboot Device
.
Create a Mobile Network Protection Profile.
Select
Objects
Security Profiles
Mobile Network Protection
and
Add
a new profile.
Give the profile a unique
Name
.
Select
Correlation
and enable
UEIP Correlation
.
Select the
Mode
you want to use.
Loose
—(Default) When the firewall detects traffic, it queries the source or destination address to find the correlated IMEI or IMSI information. If there are no results, the firewall forwards the traffic.
Strict
—Drops the traffic if the GTP-U query does not return any results.
Uncheck the
User Plane with GTP-U encapsulation
option.
Select
RADIUS
as the
Source
.
Select the
Source
that you want the firewall to use to correlate the management plane and user plane information for subscriber-level and equipment-level Security policy enforcement. The firewall inspects traffic for the source type you select to process and extract 5G/4G identity information, such as subscriber ID (SUPI and IMSI), equipment ID (PEI and IMEI), and the IP address of the user equipment (UE), to correlate with 5G/4G subscriber Internet Protocol traffic.

(Optional) Select whether you want to log UEIP correlation events when the firewall allocates an IP address to the UE (
Log At Ueip Start
), when the firewall releases the allocated IP address (
Log At Ueip End
), or both.
The firewall logs the following GTP events during correlation that you can view by going to
Monitor
Logs
GTP
:
UEIP mapping start
UEIP mapping end
The logs contain the following user information:
Subscriber Identity (including IMSI and SUPI)
Equipment Identity (including IMEI and PEI)
End User IP address allocated to UE
Access Point Name (APN)
Radio Access Technology (RAT)
Create a Security policy to identify and allow RADIUS traffic between the SMF and the RADIUS server.
There are two methods for policy creation based on the necessary level of security between the SMF and the RADIUS server. Select the appropriate method based on your security needs.
(
Recommended
) To allow all traffic between the SMF and RADIUS server zone, as well as the UPF and Data Network zones:
Select
Policies
Security
and
Add
a unique
Name
for the rule in the
General
tab.
In the
Source
tab,
Add
the
Source Zone
as
Any
and the
Source Address
as
Any
.
In the
Destination
tab,
Add
the
Destination Zone
as
Any
and the
Destination Address
as
Any
.
In the
Application
tab,
Add
radius
as the
Application
you want to allow.
In the
Service/URL Category
tab, select the
Service
as
Any
.
In the
Actions
tab, select the
Action
as
Allow
.
Attach the
Mobile Network Protection profile
to the Security policy rule by selecting
Profiles
and selecting the profile as the
Profile Type
.
Select
Log at Session End
if it is not already selected.
To allow RADIUS application traffic only between the SMF and the RADIUS server:
Select
Policies
Security
and
Add
a unique
Name
for the rule in the
General
tab.
In the
Source
tab,
Add
the
Source Zone
and
Source Address
of the interface that the SMF uses to communicate with the RADIUS server.
In the
Destination
tab,
Add
the
Destination Zone
and
Destination Address
for the interface that contains the IP address of the RADIUS server.
In the
Application
tab,
Add
radius
as the
Application
you want to allow.
In the
Service/URL Category
tab, select the
Service
as
Any
.
In the
Actions
tab, select the
Action
as
Allow
.
Attach the
Mobile Network Protection profile
to the Security policy rule by selecting
Profiles
and selecting the profile as the
Profile Type
.
Select
Log at Session End
if it is not already selected.
Create a custom application and a Security policy that uses the custom application. (
Required if you allow traffic between the SMF and RADIUS server only
)
Because the firewall applies this policy rule first, it processes the first packet of all user traffic and enables UEIP database querying, move this policy rule above any other policy rules in your Security policy for user traffic on the N6 interface. Any application-specific or IMSI/IMEI-based policy rules must occur after this policy rule.
Select
Objects
Applications
and
Add
a unique
Name
for the application (for example,
radius-ueip
).

Select
Policies
Security
and
Add
a unique
Name
for the policy rule.
In the
Source
tab,
Add
the zone that contains traffic to the UPF as the
Source Zone
and select
Any
as the
Source Address
. If you use an IP pool for the UE IP address, add the IP pool as the
Source Address
.
Don't select anything in the
Source Subscriber
or
Source Equipment
tabs.
In the
Destination
tab,
Add
the zone that contains traffic to the Packet Data Network as the
Destination Zone
and select
Any
as the
Destination Address
.
In the
Application
tab,
Add
the
Application
you created in step 4.1.
In the
Service/URL Category
tab, select
Any
as the
Service
.
In the
Actions
tab, select
Allow
as the
Action
.
Attach the
Mobile Network Protection profile
to the Security policy rule by selecting
Profiles
and selecting the profile you created in step 3 as the
Profile Type
.
Select
Log at Session End
if it is not already selected.
Create Security policy rules for user equipment (UE) traffic based on the criteria you want to use, such as IP address, application, URL category, IMSE, or IMEI.
Select
Policies
Security
and
Add
a unique
Name
for the rule.
In the
Source
tab,
Add
the
Source Zone
and
Source Address
.
If you use an IP pool for the UE IP address, add the IP pool as the
Source Address
.
In the
Source
tab,
Add
the
Source Subscriber
and if required, the
Source Equipment
.
In the
Destination
tab,
Add
the
Destination Zone
and
Destination Address
the address of the servers in the corporate network or MEC site or use
any
for internet access.
In the
Application
tab,
Add
the
Application
or applications you want to allow, such as
dns
,
web-browsing
, or
ssl
.
In the
Service/URL Category
tab, select the type or types of
Service
you want to allow.
In the
Actions
tab, select the
Action
you want to take for the selected traffic (
Allow
the traffic or
Deny
it).
Select
Log at Session End
if it is not already selected.
Confirm that the profile is
Enabled
(
Policies
Security
Security Policy Rule
Actions
Profile Setting
Mobile Network Protection
) and
Commit
the changes.
Verify your configuration is correct.
Verify the session traffic on the firewall using the following CLI commands.
show session all filter application radius
show session all filter source
<IP_address_of_UE>
(where
<IP_address_of_UE>
is the IP address of the user equipment).
Verify the mappings on the firewall display
radius
as the source (
src
).
View the logs (
Monitor
Logs
GTP
) and verify that the
GTP Event Type
displays
UEIP mapping start
and
UEIP mapping end
.

Verify the Traffic logs (
Monitor
Logs
Traffic
) display the IMSI or IMEI in the
Subscriber Identity
column for the UE traffic.

Use the Global Counters to verify the configuration.