防火墙

firewall / CL:堵[du3]

to protect / to defend / to guard against / to prevent

to protect against fire

fire / urgent / ammunition / fiery or flaming / internal heat (Chinese medicine) / hot (popular) / classifier for military units (old) / Kangxi radical 86

firewall

variant of 牆|墙[qiang2], wall

wall / CL:面[mian4],堵[du3]