Synchronet v3.19b-Win32 (install) has been released (Jan-2022).

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IP Address Filter

The ip.can file is an optional configuration file located in the Synchronet text directory.

This file contains IP addresses for which Synchronet servers and dynamic services will not allow incoming connections. Note: static services may or may not filter connections based on this file depending on the design of the static service.

The file can be created or edited using most any common text editor. The contents of the file conform to the Synchronet filter files syntax to support wildcards (e.g. blocks of IP addresses) and comments.

Synchronet servers and services can write to this file (automatically adding IP addresses to be blocked) under the following conditions:

  1. The LoginAttemptFilterThreshold key value in one of the sections of the sbbs.ini file is non-zero and the relevant server has detected consecutive failed login attempts from the same IP address exceeding the specified threshold, the IP address will be automatically added to the file (with a detailed comment)
  2. The JavaScript system.filter_ip() method is used in a Synchronet service or module to block a specific IP address

Note: there is currently no mechanism to automatically remove blocked IP addresses from the file (e.g. after a certain period of time).

Rejected connections will be logged. Example:

Nov 20 13:05:23 cvs sbbs: ftp  0013 !CLIENT BLOCKED in ip.can:

To block IP addresses without logging (i.e. silently reject), use the text/ip-silent.can filter file instead.

See Also