LDP
/
LDP
mirror of https://github.com/tLDP/LDP
0
1
Fork 0
Code Releases Activity

updated

This commit is contained in:
gferg 2003-07-29 19:48:36 +00:00
parent 73626ffbaf
commit 60464e5c13
5 changed files with 1980 additions and 1746 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

169
LDP/howto/docbook/Apache-WebDAV-LDAP-HOWTO.xml
View File

@ -1,10 +1,9 @@
<?xml version="1.0" encoding="ISO-8859-1"?>
<!DOCTYPE article PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN"
"http://docbook.org/xml/4.1.2/docbookx.dtd" []>
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE article PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN" "http://docbook.org/xml/4.1.2/docbookx.dtd">
<article>
<articleinfo>
<title>Apache based WebDAV Server with LDAP and SSL </title>
@ -23,9 +22,18 @@
<revhistory>
<revision>
<revnumber>v4.0.1</revnumber>
<date>2003-07-27</date>
<authorinitials>sa</authorinitials>
<revremark>
Added more information to the SSL section.
</revremark>
</revision>
<revision>
<revnumber>v4.0</revnumber>
<date>2002-06-29</date>
<date>2003-06-29</date>
<authorinitials>sa</authorinitials>
<revremark>
Updated the HOWTO for Apache 2.0. Also the source is in XML
@ -106,7 +114,7 @@
<para>
The tools needed to achieve this objective are:</para>
<orderedlist numeration="lowerroman">
<orderedlist numeration="lowerroman">
<listitem>C Compiler e.g. GCC</listitem>
<listitem>Apache 2 Web Server</listitem>
<listitem>LDAP Module for Apache</listitem>
@ -181,7 +189,7 @@ Download the iPlanet LDAP SDK from <ulink url="http://wwws.sun.com/software/down
<sect3><title>OpenSSL Engine</title>
<para>Next we need to install the OpenSSL Engine</para>
<para>OpenSSL is required to create and manage SSL certificates on the webserver. The installion is also necessary for the lib files that will be used by the SSL module for apache.</para>
<para>OpenSSL is an open source implementation of the SSL/TLS protocol. It is required to create and manage SSL certificates on the webserver. The installion is also necessary for the lib files that will be used by the SSL module for apache.</para>
<para>Change to the directory where you placed the OpenSSL source code files</para>
<screen> <command># cd /tmp/download</command>
<command># gzip -d openssl.x.x.tar.gz</command>
@ -191,6 +199,7 @@ Download the iPlanet LDAP SDK from <ulink url="http://wwws.sun.com/software/down
<command># make test</command>
<command># make install</command>
</screen>
<para>Upon successful completion of the <command>make install</command> the openssl binaries should reside in <filename type="directory">/usr/local/ssl</filename></para>
</sect3>
</sect2>
@ -274,8 +283,28 @@ mysql 3256 3237 0 May29 ? 00:06:58 /usr/local/mysql/bin/mysqld --de
</screen>
</sect2>
<sect2><title>PHP</title>
<sect2><title>CERT DB for LDAPS://</title>
<para>You will also need to get the cert7.db and key7.db from <ulink url="http://www.xml-dev.com/xml/key3.db">http://www.xml-dev.com/xml/key3.db</ulink> and <ulink url="http://www.xml-dev.com/xml/cert7.db">http://www.xml-dev.com/xml/cert7.db</ulink> and place it in the <filename>/usr/local/apache2/sslcert/</filename>directory.</para>
</sect2>
<sect2><title>PHP</title>
<para>Unzip the PHP Source Files</para>
<screen><command>gzip -d php-xxx.tar.gz</command>
<command>tar -xvf php-xxx.tar</command>
</screen>
<para>Configure and run the make command</para>
<screen><command>cd php-xxx</command>
<command>./configure --with-mysql --with-apxs=/usr/local/apache2/bin/apxs</command>
</screen>
<para>Compile the source code</para>
<screen><command># make </command>
<command># make install</command>
</screen>
<para>Copy the php.ini file to the appropriate directory</para>
<screen><command>cp php.ini-dist /usr/local/lib/php.ini</command>
</screen>
</sect2>
</sect1>
@ -404,7 +433,7 @@ please use: </para>
<screen><command># ps -ef | grep httpd</command></screen>
<para>Create a test directory called '<filename>DAVtest</filename>'
under <filename>/usr/local/apache/htdocs</filename> :</para>
under <filename>/usr/local/apache2/htdocs</filename> :</para>
<para><command># mkdir /usr/local/apache/htdocs/DAVtest</command></para>
@ -572,18 +601,17 @@ has access to this folder.
</sect1>
<sect1 id="ssl"><title>Implementing and using SSL to secure WebDAV traffic</title>
<sect1 id="ssl"><title>Implementing and using SSL to secure HTTP traffic</title>
<para>
Security of the data stored on a file server is very important these days. Compromised data can cost thousands of dollars to
company. In the last section, we compiled LDAP authentication module into the Apache build to provide a Authentication
mechanism. However HTTP traffic is very insecure, and all data is transferred in clear text - meaning, the LDAP authentication
(userid/passwd) will be transmitted as clear text as well. This create a problem. Anyone can sniff these userid/passwd and gain
(userid/passwd) will be transmitted as clear text as well. This creates a problem. Anyone can sniff these userid/passwd and gain
access to DAV store. To prevent this we have to encrypt HTTP traffic, essentially HTTP + SSL or HTTPS. Anything transferred over
HTTPS is encrypted, so the LDAP userid/passwd can not be sniffed. HTTPS runs on port 443. The resulting build from the last
HTTPS is encrypted, so the LDAP userid/passwd can not be easily deciphered. HTTPS runs on port 443. The resulting build from the last
section's compilation process will have Apache to listen to both port 80 (normal HTTP) and 443 (HTTPS). If you are just going
to use this server for DAV, then I will highly suggest that you close port 80. In this section of the HOWTO I will provide some
information regarding SSL and maintaining SSL on a WebDAV server. However this is a not limited to a DAV server, it can be
used on any web server.
information regarding SSL and maintaining SSL on a Apache HTTP server.
</para>
<sect2><title>Introduction to SSL</title>
@ -607,12 +635,10 @@ The following is a over-simplified structure of the layers involved in SSL.
</para>
<sect3><title>Encryption algorithms used in SSL</title>
<para>
There are 2 kinds of encryption algorithms used in SSL.
There are three kinds of cryptographic techniques used in SSL: Public-Private Key, Symmetric Key, and Message Digest.
</para>
<para>
<emphasis role="strong">Public-Private Key Crytography - Initiating SSL connection: </emphasis> This algorithm is used for initiating the SSL session. In this algorithm, the encryption must
be performed using the Public Key, and the decryption can only be performed using the Private Key. The Web-server holds the
private Key, and sends the Public key to the client. The public key is sent to the client in a certificate.
<emphasis role="strong">Public-Private Key Crytography - Initiating SSL connection: </emphasis> In this algorithm, encryption and decryption is performed using a pair of private and public keys. The Web-server holds the private Key, and sends the Public key to the client in the Certificate.
</para>
<orderedlist>
@ -635,20 +661,20 @@ private Key, and sends the Public key to the client. The public key is sent to t
<para>If everything is successful the SSL connection is initiated.</para>
</listitem>
</orderedlist>
<note><title>Note:</title><para>Anything encrypted with Private Key can only be decrypted by using the Public Key. Similarly anything encrypted using the Public Key can only be decrypted using the Private Key. There is a common mis-conception that only the Public Key is used for encryption and Private Key is used for decryption. This is not case. Any key can be used for encryption/decryption. However if one key is used for encryption then the other key must be used for decryption. e.g. A message can not encrypted and then decrypted using only the Public Key.</para>
<para><emphasis>Using Private Key to encrypt and a Public Key to decrypt ensures the integrity of the sender (owner of the Private Key) to the recipients. Using Public Key to encrypt and a Private Key to decrypt ensures that only the inteded recipient (owner of the Private Key) will have access to the data.</emphasis>(i.e. only the person who holds the Private Key will be able to decipher the message).</para></note>
<para>
<emphasis role="strong">Symmetric Cryptography - Actuall transmission of data</emphasis>: After the SSL connection has been established, Symmetric cryptography
is used to encrypting data. Public-Private Key cryptography is CPU cycle intensive, so Symmetric cryptography is used. In
symmetric cryptography the data can be encrypted and decrypted using the same key. The Key for symmetric cryptography was
exchange in the initiation process.
</para>
<emphasis role="strong">Symmetric Cryptography - Actual transmission of data</emphasis>: After the SSL connection has been established, Symmetric cryptography is used for encryption data as it uses CPU cycles. In symmetric cryptography the data can be encrypted and decrypted using the same key. The Key for symmetric cryptography is exchanged during the initiation process, using Public Private Key Cryptography. </para>
<para><emphasis role="strong">Message Digest</emphasis> The server uses message digest algoritm such as HMAC, SHA, MD5 to verify the integrity of the transferred data.</para>
</sect3>
</sect2>
<sect2><title>Test Certificates</title>
<para>While compiling Apache we created a test certificate. We used the makefile provided by
mod_ssl to create this custom Certificate. We used the command:
<screen># make certificate TYPE=custom</screen>
<screen><command># make certificate TYPE=custom</command></screen>
</para>
<para>This certificate can be used for testing purposes.</para>
@ -656,10 +682,7 @@ mod_ssl to create this custom Certificate. We used the command:
<sect2><title>Certificates for Production use</title>
<para>
For production use you will need a certificate from a CA.
CA or Certificate Authorities are certificate vendors, who are listed as a Trusted CA in user's browser client. As mentioned in
the Encryption Algorithms section, if the CA is not listed as a trusted authority, your user will get a warning message when
trying to connect to a secure location.
For production use you will need a certificate from a Certificate Authority (hereafter CA). Certificate Authorities are certificate vendors, who are listed as a Trusted CA in the user's browser. As mentioned in the Encryption Algorithms section, if the CA is not listed as a trusted authority, your user will get a warning message when trying to connect to a secure location.
</para>
<para>
Similarly the test certificates will also cause a warning message to appear on the user's browser.
@ -676,26 +699,80 @@ and send it to the CA of your choice.
</para>
<screen>
<command>cd /usr/local/apache/conf/</command>
<command>/usr/local/ssl/bin/openssl req -new -nodes -keyout private.key -out public.csr</command>
<command># cd /usr/local/apache/conf/</command>
<command># /usr/local/ssl/bin/openssl req -new -nodes -keyout private.key -out public.csr</command>
Generating a 1024 bit RSA private key
............++++++
....++++++
writing new private key to 'private.key'
-----
You are about to be asked to enter information that will be incorporated
into your certificate request.
What you are about to enter is what is called a Distinguished Name or a DN.
There are quite a few fields but you can leave some blank
For some fields there will be a default value,
If you enter '.', the field will be left blank.
-----
Country Name (2 letter code) [AU]:US
State or Province Name (full name) [Some-State]:California
Locality Name (eg, city) []:San Jose
Organization Name (eg, company) [Internet Widgits Pty Ltd]:Seagate
Organizational Unit Name (eg, section) []:Global Client Server
Common Name (eg, YOUR name) []:xml.seagate.com
Email Address []:saqib@seagate.com
Please enter the following 'extra' attributes
to be sent with your certificate request
A challenge password []:badpassword
An optional company name []:
</screen>
<para>
At this point you will be asked several about your server location, to generat the Certificate Signing Request</para>
At this point you will be asked several questions about your server to generate the Certificate Singning Request</para>
<para>
Note: You Common Name is the DNS name of your webserver e.g. dav.server.com . If you put in anything else, it will NOT work. Remember the passwd that you use, for future reference.
Note: You Common Name (CN) is the DNS name of your webserver e.g. dav.server.com . If you put in anything else, it will NOT work. Remember the passwd that you use, for future reference.
</para>
<para>Once the process is complete, you will have private.key and a public.csr . At this pointe the public.key is not encrypted. To encrypt"
<para>Once the process is complete, you will have <filename>private.key</filename> and a <filename>public.csr</filename> . You will need to submit the <filename>public.csr</filename> to the Certification Authority. At this pointe the public.key is not encrypted. To encrypt:
</para>
<screen>
<command>mv private.key private.key.unecrpyted</command>
<command>/usr/local/ssl/bin/openssl rsa -in private.key.unecrpyted -des3 -out private.key</command>
<screen> <command># mv private.key private.key.unecrpyted</command>
<command># /usr/local/ssl/bin/openssl rsa -in private.key.unecrpyted -des3 -out private.key</command>
</screen>
</sect2>
<sect2><title>Installing Server Private Key, and Server Certificate</title>
<para>Once the Certification Authority processes your request, they will send an encoded certificate back to you. You will need to place this certificate on the server, and tell Apache where to find it.</para>
<para>For this example, the Private Key is placed in the <filename type="directory">/usr/local/apache2/conf/ssl.key/</filename> directory, and the Sever Certificate is placed in the <filename type="directory">/usr/local/apache2/conf/ssl.crt/</filename>.</para>
<para>Copy the file received from the Certification to a file called <filename>server.crt</filename> in the <filename type="directory">/usr/local/apache2/conf/ssl.crt/</filename>.</para>
<para>And place the private.key generated in the previous step in the <filename type="directory">/usr/local/apache2/conf/ssl.key/</filename></para>
<para>Then modify the <filename type="directory">/usr/local/apache2/conf/ssl.conf</filename> to point to the correct Private Key and Server Certificate files:</para>
<screen>
# Server Certificate:
# Point SSLCertificateFile at a PEM encoded certificate. If
# the certificate is encrypted, then you will be prompted for a
# pass phrase. Note that a kill -HUP will prompt again. Keep
# in mind that if you have both an RSA and a DSA certificate you
# can configure both in parallel (to also allow the use of DSA
# ciphers, etc.)
<emphasis role="strong">SSLCertificateFile /usr/local/apache2/conf/ssl.crt/server.crt</emphasis>
#SSLCertificateFile /usr/local/apache2/conf/ssl.crt/server-dsa.crt
# Server Private Key:
# If the key is not combined with the certificate, use this
# directive to point at the key file. Keep in mind that if
# you've both a RSA and a DSA private key you can configure
# both in parallel (to also allow the use of DSA ciphers, etc.)
<emphasis role="strong">SSLCertificateKeyFile /usr/local/apache2/conf/ssl.key/private.key</emphasis>
#SSLCertificateKeyFile /usr/local/apache2/conf/ssl.key/server-dsa.key
</screen>
</sect2>
<sect2><title>Removing passphrase from the RSA Private Key</title>
<para>RSA Private Key stored on the webserver is usually encrypted, and you need a passphrase to parse the file. That is why you
@ -712,11 +789,9 @@ are prompted for a passphrase when start Apache with modssl:</para>
</screen>
</para>
<para>Encrypting the RSA Private Key is very important. If somebody gets hold of the you "Unencrypted RSA Private Key" he/she can easily
impersonate your webserver. If the Key is encrypted, the hacker can not do anything without the passphrase. </para>
<para>Encrypting the RSA Private Key is very important. If a cracker gets hold of your "Unencrypted RSA Private Key" he/she can easily impersonate your webserver. If the Key is encrypted, the cracker can not do anything without brute forcing the passphrase. Use of a strong (ie: long) passphrase is encouraged. </para>
<para>However encrypting the Key can sometimes be nuisance, since you will be prompted for a passphrase everytime you start the web-server.
Specially if you are using rc scripts to start the webserver at boot time, the prompt for passphrase creates problems.</para>
<para>However encrypting the Key can sometimes be nuisance, since you will be prompted for a passphrase everytime you start the web-server. Especially if you are using rc scripts to start the webserver at boot time. The prompt for a passphrase will stop the boot process, waiting for your input.</para>
<para>You can get rid of the passphrase prompt easily by decrypting the Key. However make sure that no one can hold of this Key. I would
recommend Hardening and Securing guidelines be followed before decrypting the Key on the webserver.</para>
@ -742,18 +817,26 @@ One way to secure the decrypted Private Key is to make readable only by the root
<sect2><title>Trusted Certificate Authorities</title>
<para>The following is list of Certificate Authorities that are trusted by the various browsers:</para>
<orderedlist>
<orderedlist numeration="lowerroman">
<listitem>
<para><ulink url="http://www.verisign.com">Verisign</ulink></para>
<para><ulink url="http://www.baltimore.com/">Baltimore</ulink></para>
</listitem>
<listitem>
<para><ulink url="http://www.entrust.com/">Entrust</ulink></para>
</listitem>
<listitem>
<para><ulink url="http://www.thawte.com">Thawte</ulink></para>
</listitem>
<listitem>
<para><ulink url="http://www.verisign.com">Verisign</ulink></para>
</listitem>
</orderedlist>
</sect2>
</sect1>
</article>

1012
LDP/howto/docbook/Linux-Gamers-HOWTO.sgml
View File

File diff suppressed because it is too large Load Diff

29
LDP/howto/docbook/XFree86-R200.xml
View File

@ -2,7 +2,6 @@
<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN"
"http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" [
]>
<!-- TODO: ADD ALTERNATIVE 5 (SCHNEIDER-DIGITAL DRIVERS) -->
<book>
<bookinfo>
@ -14,8 +13,20 @@
</affiliation>
</author>
<pubdate>2002-09-12</pubdate>
<revhistory>
<pubdate>2003-07-27</pubdate>
<revhistory>
<revision>
<revnumber>1.3</revnumber>
<date>2003-07-27</date>
<authorinitials>HS</authorinitials>
<revremark>Aternative 2 updated.</revremark>
</revision>
<revision>
<revnumber>1.2.1</revnumber>
<date>2003-07-15</date>
<authorinitials>HS</authorinitials>
<revremark>Date fixes.</revremark>
</revision>
<revision>
<revnumber>1.2</revnumber>
<date>2003-07-14</date>
@ -112,10 +123,8 @@ use XFree86. The bad news is that this driver only supports 2D (meaning DRI won'
</sect1>
<sect1 id="alt2">
<title>Experiences with ATI's own driver - DEPRECATED</title>
<para>This alternative is now deprecated, since ATI has suddenly decided that their cards do not support Linux.
ATI currently have no Linux drivers available for the R200 chipset. Please let me know if this changes without
me noticing it.</para>
<title>Experiences with ATI's own driver</title>
<para>This alternative uses ATIs own drivers for the Linux operating system. The drivers are developed by 3rd party Linux developers for ATI. The driver supports some 3D acceleration, and works almost "out of the box".</para>
</sect1>
<sect1 id="alt3">
@ -188,9 +197,9 @@ Driver "ati"
</sect1>
<sect1 id="using_ati_driver">
<title>Alternative 2: Using ATI's own R200 Driver - DEPRECATED</title>
<title>Alternative 2: Using ATI's own R200 Driver</title>
<para>ATI's R200 driver comes in two distributions - one for XFree4.1 and one for XFree4.2. You can download ATIs driver from <ulink url="http://www.ati.com/support/products/pc/radeon8500/linux/radeon8500linuxdrivers.html">here</ulink>. Sadly, for those of us who do not use RedHat, the package is only available in RPM format (yes, I know that other distributions support RPM as well, but far from all of them). For those of us who do not have RPM support, <literal>alien</literal> is the program to use. Alien converts between various package formats. To convert the ATI driver package to a <filename>.deb</filename> package, use <command>alien --to-deb packagename.rpm</command>. To convert it to a <filename>.tgz</filename> package, use <command>alien --to-tgz packagename.rpm</command>.</para>
<para>ATI's R200 driver comes in two distributions - one for XFree4.1 and one for XFree4.2. You can download ATIs driver from <ulink url="http://mirror.ati.com/support/drivers/linux/radeon-linux.html">here</ulink>. Sadly, for those of us who do not use a RedHat-based or other RPM-supporting distribution, the package is only available in RPM format. For those of us who do not have RPM support, <literal>alien</literal> is the program to use. Alien converts between various package formats. To convert the ATI driver package to a <filename>.deb</filename> package, use <command>alien --to-deb packagename.rpm</command>. To convert it to a <filename>.tgz</filename> package, use <command>alien --to-tgz packagename.rpm</command>.</para>
<para>You are now ready to install the driver. To install it, use:</para>
@ -315,7 +324,7 @@ First, download the driver file for either
<title>Links</title>
<itemizedlist>
<listitem><para><ulink url="http://www.ati.com/support/products/pc/radeon8500/linux/radeon8500linuxdrivers.html">http://www.ati.com/support/products/pc/radeon8500/linux/radeon8500linuxdrivers.html</ulink> - ATIs R200 driver for XFree86 4.1.x/4.2.x - DEPRECATED</para></listitem>
<listitem><para><ulink url="http://mirror.ati.com/support/drivers/linux/radeon-linux.html">http://mirror.ati.com/support/drivers/linux/radeon-linux.html</ulink> - ATIs R200 driver for XFree86 4.1.x/4.2.x </para></listitem>
<listitem><para><ulink url="http://gatos.sf.net/">http://gatos.sf.net/</ulink> - The GATOS Projects homepage - ATI drivers and utilities</para></listitem>
<listitem><para><ulink url="http://gatos.sourceforge.net/project/showfiles.php?group_id=12629">http://gatos.sourceforge.net/project/showfiles.php?group_id=12629</ulink> - The download section of the GATOS project's website.</para></listitem>
<listitem><para><ulink url="http://dri.sf.net/">http://dri.sf.net/</ulink> - The DRI Project, the Direct Rendering Infrastructure for XFree86. 3D Support, drivers and documentation.</para></listitem>

45
LDP/howto/linuxdoc/Modem-HOWTO.sgml
View File

@ -3,10 +3,11 @@
<title> Modem-HOWTO
<author>David S.Lawyer
<tt><url url="mailto:dave@lafn.org"></tt>
<date> v0.28, June 2003
<date> v0.29, July 2003
<!--
Change log: + => added more info ++ => added new topic
v0.29 July 2003 New gromitkc url, but many links in it are broken
v0.28 June 2003 Parallel port modems, lockfile permissions for wvdial
v0.27 May 2003: "Flow control" improved
v0.26 March 2003: USB clarity improved, v.92 modem "on hold" supported?,
@ -182,7 +183,7 @@ send me any other info that you think belongs in this document.
Your problem might be solved in the latest version. It will be
available to browse and/or download at LDP mirror sites. For a list
of such sites see: <url url="http://www.tldp.org/mirrors.html"> If you
only want to quickly compare the date of this the version v0.28, June 2003 with
only want to quickly compare the date of this the version v0.29, July 2003 with
the date of the latest version go to: <url
url="http://www.tldp.org/HOWTO/Modem-HOWTO.html">
@ -191,6 +192,7 @@ url="http://www.tldp.org/HOWTO/Modem-HOWTO.html">
the source file (in linuxdoc format) at <url
url="http://www.ibiblio.org/pub/linux/docs/HOWTO/other-formats/sgml/Modem-HOWTO.sgml.gz">.
<itemize>
<item>v0.29 July 2003 New gromitkc url, but many links in it are broken
<item>v0.28 June 2003: Parallel port modems, lockfile permissions for wvdial
<item>v0.27 May 2003: "Flow control" improved
<item>v0.26 March 2003: USB clarity improved, v.92 modem "on hold" supported?,
@ -273,10 +275,10 @@ name="All Modems"> for further instructions.
<sect2> Internal Modems (ISA, PCI and AMR)
<p> The first thing to do is to make sure that the modem will work
under Linux since (as of 2002) many modems don't. See <url
url="http://www.idir.net/~gromitkc/winmodem.html" name="modem list">.
If the modem is both PnP and directly supported by the serial driver
(kernel 2.4 +) then there is no configuring for you to do since the
Linux serial driver will configure it.
url="http://personal.myvine.com/~gromitkc/winmodem.html" name="modem
list">. If the modem is both PnP and directly supported by the serial
driver (kernel 2.4 +) then there is no configuring for you to do since
the Linux serial driver will configure it.
To physically install a modem card, remove the cover of the PC by
/removing some screws (perhaps screw size 6-32 in the U.S.). Find a
@ -346,7 +348,7 @@ dialing program. If you have an Internet Service Provider (ISP) you
might configure one of these : wvdial, gnome-ppp, modem lights (Gnome)
or kppp. They not only dial out but start PPP, which you need to
connect to the Internet. Otherwise, you might try configuring the
mimicom dialer which isn't designed for connecting to the Internet,
minicom dialer which isn't designed for connecting to the Internet,
but is good for testing. Whether it's minicom or a dialer that starts
PPP, set the serial port speed to a baud rate a few times higher than
the bit rate of your modem. See <ref id="speed_table" name="Speed
@ -581,7 +583,7 @@ details.
<item> <url url="http://linmodems.org"> is a project to turn winmodems
into linmodems. Has a mailing list.
<item>Conexant+Rockwell-modem-HOWTO
<item><url url="http://www.idir.net/~gromitkc/winmodem.html"
<item><url url="http://personal.myvine.com/~gromitkc/winmodem.html"
name="modem list">. Has links to linmodem info.
<item> PCTel-HSP-MicroModem-Configuration-mini-HOWTO
</itemize>
@ -5035,7 +5037,7 @@ than in the HOWTO.
<sect1> Web Sites <label id="web_sites">
<p> <itemize>
<item> Modem List of modems which work/don't_work under Linux
<url url="http://www.idir.net/~gromitkc/winmodem.html">
<url url="http://personal.myvine.com/~gromitkc/winmodem.html">
<item> <url url="http://serial.sourceforge.net/" name="Linux Serial
Driver home page"> Includes info about support for PCI modems.
<item>Hayes AT modem commands
@ -5058,7 +5060,7 @@ name="Controlling your Modem with AT Commands">
name="Navas 28800-56K Modem FAQ">
<item> <url url="http://www.net-boy.com" name="Curt's High Speed
Modem Page">
<item> Much info on 56k modems <url url="http://808hi.com/56k/"
<item> Much info on 56k modems <url url="http://modemsite.com/56k/"
name= "56k Modem = v.Unreliable">
<item> <url url="http://www.56k.com/links/Modem_Manufacturers/"
name="Links to modem manufacturers">
@ -5342,7 +5344,24 @@ predict what echos the transmitted signal will cause. Then this
predicted echo signal is subtracted from the received signal. This
cancels out the echoes.
<sect> Appendix B: (Reserved for future use)
<sect> Appendix B: Analog Voice Infeasible Over Non-Voice Modem
<p>Sometimes people look for software that will allow them to transmit
ordinary analog voice over a modem that doesn't support voice. It
doesn't exist since it's just not very feasible to do this. Of
course, one can use VOIP to send digital voice over a modem. And when
one makes a call and the other side picks up the line, one might be
able to hear voice for a few seconds until negotiations for a
connection begin.
But once a modem is connected, sending analog voice over it just isn't
feasible. For phase-amplitude modulation, carrier frequencies of
fixed values are used which doesn't allow the continuously variable
frequencies required in analog voice. V.90 and V.92 might be feasible,
but if line conditions deteriorate, they fall back to phase-amplitude
modulation which won't work. Furthermore, V.90 uses phase-amplitude
in one direction. Also, both V.90 and V.92 don't permit all
amplitudes to be used, which limits the waveshapes which can be
created.
<sect>Appendix C: "baud" vs. "bps"
<sect1> A simple example
@ -5875,3 +5894,7 @@ V42bis (compression). Many modems support both MNP and V42.
END OF Modem-HOWTO
</article>
---------------------------------------------------------------------
To unsubscribe, e-mail: submit-unsubscribe@en.tldp.org
For additional commands, e-mail: submit-help@en.tldp.org

2471
LDP/howto/linuxdoc/User-Group-HOWTO.sgml
View File

File diff suppressed because it is too large Load Diff