At work we are all using Windows 7+, with full administrative privileges. Each PC has a dedicated IP and a proxy is used. It is set as a HTTP proxy and the option to use this for all types of connections is checked.
I have at home a "ddwrt" router with a SSH server. I use PuTTY to establish a SSH connection to my home router using port 443. PuTTY is configured for socks5 proxy tunnelling, and Firefox is enabled to send DNS requests over SSH, and Chrome also (I checked dnsleaktest, and my home configured google public DNS is used, not the company one, no DNS leaks here). I had to set company proxy in Putty to have access to Internet.
Everything is working fine, and I think I'm safe on this, but the proxy I had to set in Putty bothers me a little, as I'm not sure if that proxy can see the traffic that comes from Putty? Or the connection is still encrypted, no matter if that goes over the company proxy, the socks5 tunnel is established through the company proxy.
I guess they see the IP address putty connects to (over port 443, not 22), but that is all, they do not see anything else, just the encrypted stream between my router and PC at work.
I doubt they use any special proxy to incorporate Man in the Middle attack, it would be out of their knowledge, and guess the software would be too pricey for them.
What do you think?
Please spare me of answers that I should not use work for personal stuff, and etc., I do this with the knowledge of my boss, who is sick of the IT stuff and she basically instructed me to make access to social sites.