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vicodin tuss Compressed TCP/IP-Sessions using SSH-like tools Sebastian vicodin tuss Schreiber 2.2.2000 1. Introduction I vicodin tuss the past, we used to compress files in order to save disk vicodin tuss space. Today, disk space is cheap - but bandwidth is limi vicodin tuss ed. By compressing data streams, you achieve two goals: vicodin tuss ) You save bandwidth/transfered volume (that is important vicodin tuss f you have to pay for traffic or if your network is loade vicodin tuss .). 2) Speeding up low-bandwidth connections (Modem, GSM, vicodin tuss ISDN). This HowTo explains how to save both bandwith and vicodin tuss onnection time by using tools like SSH1, SSH2, OpenSSH or vicodin tuss LSH. 2. Compressing HTTP/FTP,... My office is connected vicodin tuss with a 64KBit ISDN line to the internet, so the maximum t vicodin tuss ansfer rate is about 7K/s. You can speed up the connection vicodin tuss by compressing it: when I download files, Netscape shows vicodin tuss p a transfer rate of up to 40K/s (Logfiles are compressab vicodin tuss e by factor 15). SSH is a tool that is mainly designed to vicodin tuss build up secure connections over unsecured networks. Furt vicodin tuss er more, SSH is able to compress connections and to do po vicodin tuss t forwarding (like rinetd or redir). So it is the approp vicodin tuss iate tool to compress any simple TCP/IP connection. "Simpl vicodin tuss " means, that only one TCP-connection is opened. An FTP-c vicodin tuss nnections or the connection between M$-Outlook and MS-Exc vicodin tuss ange are not simple as several connections are establishe vicodin tuss . SSH uses the LempleZiv (LZ77) compression algorithm - s vicodin tuss you will achieve the same high compression rate as winzi vicodin tuss /pkzip. In order to compress all HTTP-connections from my vicodin tuss intranet to the internet, I just have to execute one comma vicodin tuss d on my dial-in machine: ssh -l -C vicodin tuss -L8080::80 -f sleep 10000 = hos vicodin tuss that is located at my ISP. SSH-access is required. = my login-ID on =the web vicodin tuss roxy of my ISP My browser is configured to use localhost: vicodin tuss 080 as proxy. My laptop connects to the same socket. The vicodin tuss onnection is compressed and forwarded to the real proxy b vicodin tuss SSH. The infrastructure looks like: 64 vicodin tuss Bit ISDN My PC--------------------------------A PC (Unix/ vicodin tuss inux/Win-NT) at my ISP SSH-Client compressed vicodin tuss SSH-Server, Port 22 Port 8080 vicodin tuss | | | | vicodin tuss | | vicodin tuss | |10MBit Ethernet |100MBit vicodin tuss |not compressed |not compressed | vicodin tuss | | vicodin tuss | My second PC ISP vicodin tuss s WWW-proxy with Netscape,... Port 80 vicodin tuss (Laptop) 3. Compressing Email 3.1. Incoming Emails (PO vicodin tuss 3, IMAP4) Most people fetch their email from the mailserv vicodin tuss r via POP3. POP3 is a protocol with many disadvantages: vicodin tuss . POP3 transfers password in clear text. (There are SSL- vicodin tuss implementations of POP/IMAP and a challenge/response authentication, defined in RFC-2095/2195). 2. POP3 causes much protocol overhead: first the client requests a message than the server sends the message. After that the client requests the transferred article to be deleted. The server confirms the deletion. After that the server is ready for the next transaction. So 4 transactions are needed for each email. 3. POP3 transfers the mails without compression although email is highly compressible (factor=3.5). You could compress POP3 by forwarding localhost:110 through a compressed connection to your ISP's POP3-socket. After that you have to tell your mail client to connect to localhost:110 in order to download mai
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