TARDIS firewall

Following the Thirteenth Doctor's regeneration, a Red Supreme Dalek used a fake hologram of the Fourteenth Doctor to deceive Georgy Gold, claiming to have breached the TARDIS firewall to communicate. Georgy, a psychoplasmic construct from a simulacrum of 1966, was unaware of the concept, observing that the Doctor's TARDIS was not on fire. (COMIC: )

Earlier, during the Eleventh Doctor's life, the TARDIS had no firewalls, once resulting in it being flooded by holographic spam due to Rory Williams's usage of a superphone. (COMIC: )