I'm absolutely sure I am not in peaceful mode I'll even provide my server properties at the end of this. I've tried switching between hard mode to peaceful and back again, nothing works. I've waited a few night, with no torches and far away from spawn points, no mobs spawn, not even in the caves. This is not a bukkit server and there are no mods or plugins. This has been happening since the recent 1.7.2 update and it's only in multiplayer server. If I play a in single player they'll spawn but if I transfer the world over to multiplayer all the mobs disappear. I can spawn mobs with a spawn egg but once you kill them they're gone. I've tried several different solutions from different forums but nothing helps.
#Minecraft server properties #Wed Nov 20 10:50:50 PST 2013 generator-settings= op-permission-level=4 allow-nether=true level-name=world enable-query=false allow-flight=false announce-player-achievements=true server-port=25565 level-type=DEFAULT enable-rcon=false force-gamemode=false level-seed= server-ip= max-build-height=256 spawn-npcs=true white-list=false spawn-animals=true snooper-enabled=true hardcore=false online-mode=true resource-pack= pvp=true difficulty=1 enable-command-block=false player-idle-timeout=0 gamemode=0 max-players=5 spawn-monsters=true view-distance=10 generate-structures=true spawn-protection=1 motd=A Minecraft Server