How to Check a Proxy Before Work: 6 Checks in 5 Minutes

The proxy is connected, the browser opens, websites load. That does not yet mean everything is set up right. The country may be detected wrong, DNS requests may bypass the proxy, and the browser may leak your real IP through WebRTC. Any one of these mistakes is enough for a platform.

Below are the checks we run ourselves for a new connection, in the order that is convenient to go through them. It takes about five minutes.

1. Which IP the website sees

First make sure the traffic actually goes through the proxy. On the command line one command is enough:

curl -x http://LOGIN:PASSWORD@proxy-dealer.com:5555 https://api.ipify.org

# the same over SOCKS5
curl -x socks5h://LOGIN:PASSWORD@proxy-dealer.com:5556 https://api.ipify.org

It should return an address different from yours. If the command shows your own IP, the app is not using the proxy, and the other checks make no sense yet.

The second command uses socks5h, not socks5. The h means the domain name is resolved on the proxy side, not on your computer. Point 3 explains why that matters.

2. Do the country and city match

GeoIP databases sometimes disagree, especially about the city. Check the address in two or three services, for example ipinfo.io, ip-api.com and whoer.net. The country should match everywhere. The city may differ within a region, and that is fine: platforms usually look at the country and region.

Look at the ASN field too, the organization the address belongs to. A residential proxy shows a home ISP such as Comcast or Deutsche Telekom, a mobile one shows a carrier such as T-Mobile or Vodafone. If you see a hosting company there, contact our support.

3. DNS leak

Before opening a website, the computer asks a DNS server for its IP address. If that request goes out directly instead of through the proxy, the website sees an American IP while the DNS request comes from a provider in your real country. Advanced anti-fraud systems notice the mismatch.

To check, open browserleaks.com/dns or dnsleaktest.com through the proxy and run the extended test. The list of DNS servers should not include your provider or the country you are actually in.

What counts as normal: the DNS server is in the same country as the proxy IP. For American addresses it sometimes shows up in neighbouring Canada, that happens. Instead of the carrier DNS you will often see Google or Cloudflare. That is fine too, millions of ordinary people use those.

How to fix a leak: in scripts use socks5h:// instead of socks5://. Through an HTTP proxy, domains are resolved on the proxy side anyway, because the client passes the site name to it, not the IP. Antidetect browsers usually close DNS leaks by default, but it is still worth checking.

4. WebRTC

Browsers need WebRTC for video calls and voice chat. To connect people directly, it can find the real IP of the device, and it does so bypassing the proxy. WebRTC runs over UDP, while an HTTP proxy, and our SOCKS5 too, carry only TCP traffic. A couple of lines of JavaScript are enough for a website to get your real address.

Open browserleaks.com/webrtc. If the Public IP field shows your real address, that is a leak. In antidetect browsers WebRTC is set in the profile: the spoofing mode or the "based on IP" mode puts in the proxy address. In regular Chrome an extension that limits WebRTC helps.

5. Time zone and language

This step checks not the proxy itself but how consistent the profile looks. If the IP is in Texas while the browser clock follows your real time zone and the browser language does not match the IP country, the picture looks odd. One such mismatch rarely leads to a ban, but together with other signals it raises the risk.

You can see the browser time zone and language on whoer.net and browserleaks.com. Antidetect browsers can match both to the IP automatically; make sure that setting is on.

6. Speed and address reputation

What remains is to make sure the address is alive and clean. Speed is easy to measure with the same curl and a timing output:

curl -x http://LOGIN:PASSWORD@proxy-dealer.com:5555 \
  -o /dev/null -s -w "connect: %{time_connect}s  total: %{time_total}s\n" \
  https://www.google.com

Through residential proxies the full response usually arrives in half a second to two seconds, depending on the country. With mobile proxies, in our measurements, a new connection opens in about a second on average: part of the time goes to picking a device and to TLS over the mobile network. Further requests on the same connection are faster. Mobile download speed ranges from a few hundred kilobytes to several megabytes per second and depends on the device and the cell load.

Address reputation is checked on scamalytics.com or ipqualityscore.com: they show whether the IP was seen in spam or fraud. A residential address sometimes has a high fraud score, because someone else may have used it before you. For a sticky session, just recreate the proxy in the dashboard to get another address. With rotation a single IP hardly matters, it changes on the next connection.

The full list

1. The IP differs from your real one.
2. The country matches in two or three GeoIP services, and the ASN shows an ISP or a carrier.
3. The DNS servers do not include your provider or your real country.
4. WebRTC does not show your real IP.
5. The browser time zone and language fit the proxy country.
6. Response time is normal and the address fraud score is low.

If something does not add up and you cannot tell why, message support from your dashboard and attach a screenshot of the check. With a browserleaks screenshot we can usually sort it out quickly.