The host at this IP address is obviously operated by cybercriminals. It is running a malware botnet controller which is being used to control infected computers (bots) around the globe using a trojan horse.
Malware botnet controller located at 149.56.43.121 on port 4199 TCP:
$ telnet 149.56.43.121 4199
Trying 149.56.43.121…
Connected to 149.56.43.121.
Escape character is ‘^]’
$ dig +short polymoly.info
149.56.43.121
Referencing malware samples (MD5 hash):
cfaa4b50ffa1d91b2e7ca835a3ce3889 — AV detection: 19 / 69 (27.54%)
f6bae28d44953239750ef459ea0517d4 — AV detection: 28 / 68 (41.18%)