Bot signals · Internet scanner
What is the CheckTLS scanner?
CheckTLS, from SecurEmail LLC, offers tools and services that help email administrators set up, test and monitor secure email. These requests come from its mail-server TLS tests.
01 · Profile
CheckTLS at a glance.
What to look for in your logs, and what the lookup API returns for its addresses.
- Type
- Internet scanner
- robots.txt
- Does not control scanning.
- API flag
risk.is_scanner
A user agent alone never sets a flag. Anyone can claim to be CheckTLS; the flag follows the address the request comes from.
02 · In the response
What a match looks like.
A lookup of a CheckTLS address sets risk.is_scanner. The flags come with geolocation and network data in the same response, for API keys on every paid plan.
The response says which kind of bot an address belongs to, not which operator. A request that claims to be CheckTLS while risk.is_scanner is false should not be trusted as CheckTLS.
{
// … location and network fields …
"risk": {
"is_ai": false,
"is_crawler": false,
"is_scanner": true
}
}
03 · Control
Block CheckTLS.
At the edge
- robots.txt won’t help. It does not control port or vulnerability scanning, so a block has to happen before the request reaches your app.
- Firewall, WAF or CDN. Many offer bot rules you can allow or deny by category.
- In your app. Look up the client address and allow or deny on
risk.is_scanner, alongside the user agent. - Never on the user agent alone. Blocking the name stops only honest clients; allowing it lets anyone in who borrows it.
04 · Questions
About CheckTLS.
What is CheckTLS?
CheckTLS, from SecurEmail LLC, offers tools and services that help email administrators set up, test and monitor secure email. These requests come from its mail-server TLS tests.
How do I block CheckTLS?
robots.txt does not control port or vulnerability scanning. Block CheckTLS at your firewall, WAF or CDN, or look up each client address and deny requests where risk.is_scanner is true.
Can I trust a request that says it is CheckTLS?
Not on the user agent alone: any client can send a bot’s name in its user agent. A user agent alone never sets a flag. Check the address with the free bot checker or the lookup API.
Which risk flag does CheckTLS set?
Its addresses set risk.is_scanner in the lookup response. The risk flags come with every paid plan.
From the blog
Go deeper.
Related bots
Recognise CheckTLS on every request.
is_ai, is_crawler and is_scanner in every lookup, on every paid plan, from 9,00 € a month (VAT included).