How to test a proxy: 8 checks before you use it
Published · 3 min read
A misconfigured proxy can leak your real IP or show inconsistencies no real user would have. Checking everything takes a few minutes. Here's the checklist we use.
1. Does the proxy respond?
The first test runs in a terminal: if the command returns an IP address, host, port and credentials are correct.
curl -x http://USER:PASSWORD@HOST:PORT https://api.ipify.org
# with SOCKS5:
curl -x socks5h://USER:PASSWORD@HOST:PORT https://api.ipify.orgIf you get an authentication error (407), check the username and password; if the connection is refused or hangs, check host, port and that the type (HTTP or SOCKS5) matches the one set on the proxy. The differences are in HTTP vs SOCKS5.
2. Is it the right IP?
Open your browser or profile with the proxy on and visit What is my IP. The address shown must be the proxy's, not your own connection's. Also check who owns the IP (ASN) with a lookup service: for a mobile proxy it should be a mobile carrier in the country you chose.
3. Is the location plausible?
Geolocation services should show the country you chose. The city may differ from what you expect: that's normal for mobile IPs, which are located where the carrier routes them onto the Internet (explained in CGNAT).
4. DNS leaks
Before connecting to a site, your computer must translate its name into an address (DNS). If that lookup goes out through your own connection instead of the proxy, your ISP's DNS server is exposed: that's a DNS leak.
Run a DNS leak test through the proxy: the servers shown should match the proxy's country, not yours. With SOCKS5 use remote DNS (socks5h in scripts, the dedicated option in Firefox).
5. WebRTC leaks
WebRTC is the technology behind in-browser video calls. To find the best route it can contact external servers without going through the proxy, revealing your real IP. Antidetect browsers handle it in the profile settings; regular browsers need dedicated settings or extensions.
The What is my IP tool includes a WebRTC test: if a public IP different from the proxy's appears, you have a leak.
6. Timezone and language
An Italian IP with a browser set to New York time and German language isn't credible. Check the browser's timezone and language match the proxy's country. Antidetect tools set them automatically from the IP if you enable the option.
7. TCP/IP fingerprint
Visit a site that compares the operating system your browser declares with the one inferred from network packets. They must match: if the profile is Windows, pick the Windows fingerprint in the client area. Full details in TCP/IP fingerprint.
8. Speed and stability
Run a speed test with the proxy on and open a few heavy pages. On a mobile network results vary through the day: test at different times before drawing conclusions.
curl -x http://USER:PASSWORD@HOST:PORT -o /dev/null -s -w "connect: %{time_connect}s total: %{time_total}s\n" https://www.google.comSummary checklist
| Check | Expected result |
|---|---|
| Connection | The curl command returns an IP |
| IP and ASN | The proxy's IP, from a mobile carrier |
| Geolocation | The country you chose |
| DNS | Servers matching the proxy's country |
| WebRTC | No public IP other than the proxy's |
| Timezone and language | Matching the proxy's country |
| TCP/IP fingerprint | Matching the profile's system |
| Speed | Stable across several runs |
Frequently asked questions
How often should I repeat the checks?
Whenever you create a profile or change proxy settings (protocol, fingerprint, country). For profiles you've already checked, a quick IP check now and then is enough.
The WebRTC test shows a local IP (192.168…): is that a problem?
Private addresses from your home network are less serious than a public IP, but it's better not to expose them. Modern browsers often hide them already behind .local addresses.
The proxy works in curl but not in my software: why?
Almost always the type selected in the software doesn't match (HTTP instead of SOCKS5 or vice versa) or there's a stray space in the credentials. The setup guides show the right fields for each tool.
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