NcFTPd general.cf file configuration
Don't forget to restart NcFTPd after modifying the general.cf file.
This option lets you set the size of each data connection's socket send buffer (using the SO_SNDBUF socket option). The value you specify should be in bytes, and must be a minimum of 512 bytes.
This requires the corresponding functionality to be implemented by the TCP/IP stack and may not be available on every operating system. You will almost never need to use this option, since the default setting works fine, but you can experiment with this to increase performance or conserve memory.
If memory conservation is the intention, you may want to use reduce-socket-buffer-memory instead, which sets this option for you.
Note that a remote user can override this setting by asking for a specific buffer size using a SITE RETRBUFSIZE command, so this option only applies for the default scenario when a user does not specify a custom setting (which is almost always). You can configure the maximum amount the user can request by setting the max-data-sbuf-size option.