The host at this IP address is running a malware botnet controller which is being used to control infected computers (bots) around the globe using a trojan horse.
OskiStealer botnet controller located at 104.21.3.183 on port 80 (using HTTP POST):
hXXp://hp-tv.tk/6.jpg
$ dig +short hp-tv.tk
104.21.3.183
Other malicious domain names hosted on this IP address:
bh.vlip.lv 104.21.3.183
dz.vlip.lv 104.21.3.183
hp-tv.tk 104.21.3.183