... Tunnel¹

This document is available for download at http://fiachra.ucd.ie/~gavin/

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... McCullagh²

www_gmc@fiachra.ucd.ie

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... Server³

See http://www.cygwin.com/xfree/

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... XFree86⁴

See http://www.xfree86.org

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... X⁵

See http://www.apple.com/downloads/macosx/apple/x11formacosx.html

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... PuTTY⁶

See http://www.chiark.greenend.org.uk/~sgtatham/putty/

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... OpenSSH⁷

See http://openssh.org/

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...ssh.com⁸

See http://ssh.com/

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... time.⁹

It is also possible to create a desktop link direct to this profile by adding to the shortcut target eg putty.exe -load <SESSION_NAME>

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... full¹⁰

NB you may have to place the mouse over the text window

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... connects¹¹

It is this connection which the firewall may block. An X connection is initiated by the Database to the user. Firewalls are generally configured to allow incoming replies only (eg requested webpages, pop3 email, etc). This connection appears to the firewall as an initiation not a reply and as such gets blocked

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...localhost:11.0 ¹²

How does this solve the problem? As we said, the firewall blocks connection initiations to the user's machine. The SSH channel is initiated by the user, so all data travelling along it is a reply. By tunneling all X display information over this pre-initiated SSH channel the firewall only has to allow replies.

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... Project¹³

See http://www.xfree86.org/

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... Project¹⁴

See http://www.cygwin.com/ http://www.cygwin.com/xfree/

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... Team¹⁵

See http://www.openssh.org/

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... PuTTY¹⁶

See http://www.chiark.greenend.org.uk/~sgtatham/

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