Get a packet capture of a GTP event, such as GTP-in-GTP,
to troubleshoot an abnormal GTP packet.
To make it easier to troubleshoot an erroneous
General Packet Radio Service (GPRS) tunneling protocol (GTP) packet,
you can capture a single GTP packet that triggered any of the following
GTP events:
GTP-in-GTP
End-user IP address spoofing
Abnormal GTPv1-C, GTPv2-C, and GTP-U messages that have a missing
mandatory Information Element (IE), invalid IE, out-of-order IE,
invalid header, or unsupported message type
Other abnormal GTPv1-C, GTPv2-C, or GTP-U messages
and look for the GTP packet
capture icon (
) at the beginning
of rows that capture troublesome GTP packets. In those rows you’ll
see the GTP Event Type (such as Abnormal GTPv2-C message with missing
mandatory IE), the Subscriber Identity (IMSI), source and destination
IP address of the packet, and other information.
If you want more details to verify the event, click the
download icon (
) to download
a packet capture file.
Export
the file to readable format
and verify that the details support the GTP event type.
In this packet capture example, the packet has two headers
titled
GPRS Tunneling Protocol
; a GTP
header inside another GTP header verifies that the GTP-in-GTP event
is not a false positive; it’s identified as a GTP-in-GTP attack.