TEID (Tunnel Endpoint Identifier)

The Tunnel Endpoint Identifier is a 32-bit field in every GTP-C and GTP-U packet that identifies the specific bearer or signalling session at the receiving endpoint. Each side of a GTP tunnel allocates and tracks its own TEIDs. Predictable, leaked, or replayed TEIDs are central to many GTP attacks (session hijacking, IMSI disclosure, denial of service), so TEID hygiene, randomisation, rapid expiry, peer validation, is a core control enforced by GTP firewalls.

Categories: Radio Access NetworkCore NetworkSignaling

TEID in context

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

The mobile core carries subscriber sessions, mobility and policy. 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.

To place TEID in the wider telecom-security picture, review 5G SA, AMF, Base Station (BS), Capacity Planning, CAPEX and CSCF — each entry cross-references back to this page so you can walk the topic in either direction.

Related terms

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