Hěnduō wàiguó wǎngzhàn bèi Fánghuǒ Chángchéng dǎngzhù le.
Many foreign websites are blocked by the Great Firewall.
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usage
A pun on 防火墙 'firewall' and 长城 'the Great Wall'. In speech people just say 墙 'the wall': a blocked site 被墙了 'got walled', and getting past it is 翻墙, 'climbing the wall'.
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The name is a translation of the English nickname. Official media do not use it, since they do not discuss the system by name.