GTP User Plane

Also known as: GTP User Plane

GTP-U (TS 29.281) is the user-plane variant of the GPRS Tunnelling Protocol that encapsulates subscriber IP packets inside UDP tunnels between RAN and core (S1-U, S5/S8-U, N3, N9). Each tunnel is identified by a TEID. GTP-U leaks and mis-scoped TEIDs are a classic vector for cross-subscriber traffic injection, redirection and data exfiltration, and are the reason a GTP firewall is mandatory on any 4G/5G user-plane border.

Categories: Radio Access NetworkCore NetworkSignaling

GTP-U in context

The radio access network is the layer where mobile devices attach to the operator's infrastructure. Attacks in this layer include IMSI catching, rogue base stations, downgrade attacks and jamming, and defenses hinge on mutual authentication, integrity-protected signaling and Open RAN supply-chain hygiene.

The mobile core is where subscriber sessions, mobility and policy live. In 4G it is the EPC (MME, HSS, S/PGW); in 5G it is the Service-Based Architecture with AMF, SMF, UPF, AUSF, UDM and the NRF. Core exposure is the difference between a single-subscriber leak and a fleet-wide breach.

To place GTP-U in the wider telecom-security picture, review IMS-AKA, N3, IAP, IPsec, TEID and GPRS.

Related terms

Related topic hubs

  • GTP Security GTP-C/GTP-U threats across S5/S8, N3/N9 and GRX/IPX borders under GSMA FS.20.
  • GTP Firewall GSMA FS.20 GTP-C/GTP-U screening on GRX/IPX borders.
  • Signaling Firewall Unified SS7/Diameter/GTP/SMS signaling firewall framework.
  • SS7 Security SS7/MAP/CAP/SCCP attacks and defenses across 2G/3G interconnect.

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