63 lines
2.8 KiB
HTML
63 lines
2.8 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
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<HTML>
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<HEAD>
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<META NAME="GENERATOR" CONTENT="SGML-Tools 1.0.9">
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<TITLE>Compressed TCP/IP-Sessions using SSH-like tools: Compressing HTTP/FTP,...</TITLE>
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<LINK HREF="Compressed-TCP-3.html" REL=next>
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<LINK HREF="Compressed-TCP-1.html" REL=previous>
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<LINK HREF="Compressed-TCP.html#toc2" REL=contents>
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<A HREF="Compressed-TCP-3.html">Next</A>
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<A HREF="Compressed-TCP.html#toc2">Contents</A>
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<HR>
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<H2><A NAME="s2">2. Compressing HTTP/FTP,...</A> </H2>
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<P>My office is connected with a 64KBit ISDN line to the internet, so the
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maximum transfer rate is about 7K/s. You can speed up the connection by compressing
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it: when I download files, Netscape shows up a transfer rate of up to 40K/s
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(Logfiles are compressable by factor 15). SSH is a tool that is mainly designed
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to build up secure connections over unsecured networks. Further more, SSH is
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able to compress connections and to do port forwarding (like rinetd or redir).
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So it is the appropriate tool to compress any simple TCP/IP connection. "Simple"
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means, that only one TCP-connection is opened. An FTP-connections or the connection
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between M$-Outlook and MS-Exchange are not simple as several connections
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are established. SSH uses the LempleZiv (LZ77) compression algorithm - so you
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will achieve the same high compression rate as winzip/pkzip. In order to compress
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all HTTP-connections from my intranet to the internet, I just have to execute
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one command on my dial-in machine:
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<P><CODE>ssh -l <login ID> <hostname> -C -L8080:<proxy_at_ISP>:80
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-f sleep 10000</CODE>
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<P><<CODE>hostname</CODE>> = host that is located at my ISP. SSH-access is required.
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<P><<CODE>login ID</CODE>> = my login-ID on <<CODE>hostname</CODE>>
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<P><CODE><proxy_at_ISP> =</CODE>the web proxy of my ISP
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<P>My browser is configured to use <CODE>localhost:8080</CODE> as proxy. My laptop connects
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to the same socket. The connection is compressed and forwarded to the real
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proxy by SSH. The infrastructure looks like:
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<P>
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<PRE>
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64KBit ISDN
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My PC--------------------------------A PC (Unix/Linux/Win-NT) at my ISP
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SSH-Client compressed SSH-Server, Port 22
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Port 8080 |
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|10MBit Ethernet |100MBit
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|not compressed |not compressed
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My second PC ISP's WWW-proxy
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with Netscape,... Port 80
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(Laptop)
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</PRE>
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<HR>
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<A HREF="Compressed-TCP-3.html">Next</A>
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