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Pure-ftpd has no direct support to prevent files with certain extensions from being uploaded. But it’s possible to accomplish this goal using a pure-ftp feature. pure-ftpd has a post-upload program that runs after each file is successfully uploaded and can run an external program. Here’s the excerpt from the pure-ftpd manual:

NAME
pure-uploadscript – Automatically run an external program after a successful upload

SYNTAX
pure-uploadscript [-p ] [-B] [-g ] [-h] -r [-u ]

So the program to run in our case can be a simple Bash script I’m going to call ban.sh

#!/bin/bash

uploaded_file=${1};
banned_extensions="zip tar rar";

for ext in ${banned_extensions};
do
count=$(echo ${uploaded_file}|grep -i ${ext}$|wc -l);
if [ "${count}" -gt "0" ];
then
rm -f ${uploaded_file}; # File with banned extension detected. Delete it.
break;
fi;
done


So you start the program in the background like this:

pure-uploadscript -p /var/run/pure-ftpd.pid -B -r /root/ban.sh

That’s all folks.