Network · AS51840

AS51840 CSL Data Centre Services Limited

AS51840 (CSL Data Centre Services Limited) looks like an internet service provider, so its addresses are mostly real home, business or mobile connections.

Network check ASN

AS51840

OwnerCSL Data Centre Services Limited
KindInternet service provider
Servers, not peopleno
IPv4 addresses5,376
IPv4 ranges6
IPv6 ranges0

Risk score0

Nothing suspicious found.

Largest IPv4 ranges

185.64.56.0/22
185.27.56.0/22
185.218.148.0/22
185.177.48.0/22
185.176.196.0/22
91.220.139.0/24

Ranges and owner from DB-IP (CC BY 4.0), updated 2026-10-22.

Check an IP address →

Detect it in code

Spot AS51840 traffic at signup.

Send the visitor's IP. The response includes the ASN, the owner and flags.hosting.

curl https://veqen-app.com/v1/ip/check \
  -H "Authorization: Bearer $VEQEN_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"ip": "203.0.113.7"}'

import os, requests

r = requests.post(
    "https://veqen-app.com/v1/ip/check",
    headers={"Authorization": f"Bearer {os.environ['VEQEN_API_KEY']}"},
    json={"ip": "203.0.113.7"},
    timeout=10,
)
result = r.json()
print(result["risk"]["verdict"], result["risk"]["reasons"])

const res = await fetch("https://veqen-app.com/v1/ip/check", {
  method: "POST",
  headers: {
    Authorization: `Bearer ${process.env.VEQEN_API_KEY}`,
    "Content-Type": "application/json",
  },
  body: JSON.stringify({"ip": "203.0.113.7"}),
});
const result = await res.json();
console.log(result.risk.verdict, result.risk.reasons);

Questions

About AS51840

Is AS51840 a datacenter or VPN network?

AS51840 (CSL Data Centre Services Limited) looks like an internet service provider, so its addresses are mostly real home, business or mobile connections.

Who owns AS51840?

AS51840 is registered to CSL Data Centre Services Limited. It announces about 5,376 IPv4 addresses.

How do I detect traffic from AS51840?

Call the Veqen IP check with the visitor's address. The response includes the ASN, the owner and whether the network is a datacenter, VPN network, relay or ISP.