Thanks for the replies everyone! In fact, I have figured out by myself that the stock Ubuntu 12.04 (at least) Squid does not provide the SSL/HTTPS support, so I have compiled it by myself. After this "GET https://.." requests became working, but not any of the CONNECT. It was also correct, that when I was testing the proxy via telnet, I used the wrong syntax for the CONNECT method. Here is the result from access.log produced by the Firefox: TCP_MISS/503 0 CONNECT www.google.com:443 - NONE/- - The host is now shown correct, but still throws 503 error. I thought the best I could get now is the guide on how to compile Squid with SSL (probably, --enable-ssl was not enough). And thanks to Rafael Akchurin seems like I've just received it! Will try now to compile again using the guide and see if anything changed. -- View this message in context: http://squid-web-proxy-cache.1019090.n4.nabble.com/Squid-3-1-19-problem-TCP-MISS-503-0-CONNECT-https-443-NONE-tp4664611p4664620.html Sent from the Squid - Users mailing list archive at Nabble.com.