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I am in corporate network where is strict proxy configured. Only http/https traffic is allowed. But I need to upload some data / manage external server with putty/winscp.

I tried to setup HTTP proxy in putty configuration. I set proxy type (HTTP), hostname and port only, other values are default including proxy command (connect %host %port\n). When I open the connection, proxy return 403 forbidden.

What can I do? Is there any chance to bypass it? Is it possible with putty? I have linux machine in internet, can I install something on it? Thanks.

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migrated from Mar 11 '14 at 9:53

This question came from our site for information security professionals.

Maybe the proxy isn't allowing any traffic to 22/tcp (assuming you're running SSH on that port) – m1ke Mar 10 '14 at 10:25
Well, it seems so. What would you recommend? Some https/ssl proxy to be installed on my internet server? – Leos Literak Mar 10 '14 at 12:08
What is the proxy software? – symcbean Mar 10 '14 at 12:29
it is squid/3.1.20 – Leos Literak Mar 10 '14 at 12:30
Is it configured to allow CONNECT to port 22? Is this allowed in the firewall config? – symcbean Mar 10 '14 at 12:36
up vote 1 down vote accepted

Probably the network proxy/firewall doesn't allow outbound connections to 22/tcp. You'd need to run the service on a port that's allowed (outbound) by your proxy/firewall, such as 443/tcp.

An alternative would be to install a "management" tool to access a shell a la "webmin" (

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You need to talk to your IT department and work with them for a solution.

Attempting to bypass security controls your employer has put in place is always a bad idea.

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Bypassing the Proxy/FW to transfer data/manage external server in a corporate environment is a no no. There is a reason why the proxy/FW is there, for compliance and security reason.

What you can do is talk to the IT/security department of your request if it is a business need. They can open rules to allow your connections if appropriate.

Corporation keeps all logs, you can be in deep shit if you can't answer why when they found out the connections logs.

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