Thankx to Marco De Vitis, Henrik Nordstrom and Joost de Heer for nice discussion. I am very new with Squid (squid/2.5.STABLE10on SuSE Linux 10.0 ). Everything is working fine with our requirements like 1. User authentication from Novell e-direcotry, 2.Single concurrent login, 3. Time based access restrictions of those users, 4. Download blocking by file extensions And 5. Upload blocking by file size. I would be very helpful if anybody can show some lights on 1. Upload blocking by File extensions 2. The explanation of the Regular expression of calculating the Content-Length i.e. "acl bigupload req_header Content-Length [[:space:]]*[[:digit:]]{6,}" which blocks all HTTP requests larger than 99,999 bytes (Thankx to Marco De Vitis), I have place acls with 50kb, 200kb, 500kb and 1mb so on. I use squid/2.5.STABLE10on SuSE Linux 10.0 Thankx, Niladri Mukherjee IT Deptt., M.N.Dastur & Company (P) Ltd. Kolkata, West Bengal. India