<i>A backdoor or 0day for a Huawei router would be of limited use to the NSA, because the control ports are behind firewalls. Hacking behind firewalls would likely give full access to the target network anyway, making any backdoors/0days in routers superfluous.<p>But embedding themselves inside the support infrastructure would give the NSA nearly unlimited access to much of the world. Huawei claims that a third of the Internet is running their devices. Almost all of it is under support contract. These means a Huawei support engineer, or a spy, can at any time reach out through cyberspace and take control of a third of the Internet hardware, located in data centers behind firewalls.</i><p>So the companies that use Huawei's products put the control ports behind their firewalls, but somehow are allowing unrestricted access through that firewall to/for Huawei's support mechanism?<p>Is that common?