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<td valign="bottom" width="80%"><font size="6">EchoLink Proxy</font></td>
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<p><font size="3"><a href="#background">[Background]</a> <a href="#installation">[Installation]</a>
<a href="#faq">[FAQs]</a> <a href="#status">[Status Pages]</a></font></p>
<h2><font face="Verdana, Arial, Helvetica"><font size="3"><a name="background"></a>Background</font></font></h2>
<p><font size="2">EchoLink is a peer-to-peer system, by design. This means that
when your node is connected to another node over the Internet, the voice and
text signals are sent directly from one node to the other, rather than going
through some central server. This helps ensure that the system is
scalable and reliable.</font></p>
<p><font size="2">Unfortunately, there are certain situations in which peer-to-peer
connections such as these are difficult to establish. A growing number of
Internet providers are offering "one-way" access to the Internet —
allowing your computer to initiate a connection, but not to accept
one. These include <i>wireless community networks, </i>or <i>hotspots</i>.
An example is the wireless Internet service now being provided by many hotels
to their guests. Guests with wireless-enabled laptop computers can check
their e-mail and surf the Web from their rooms. The hotel uses a router
with a fast Internet connection and a single public address (or a small pool of
addresses) shared amongst all guests. This arrangement does not work with
EchoLink, because the guests' computers are not reachable from the Internet.</font></p>
<h2><font face="Verdana, Arial, Helvetica"><font size="3">A Solution</font></font></h2>
<p><font size="2">A solution to this problem is to split the EchoLink software into two
pieces <font face="Trebuchet MS">—</font> one that runs on your laptop, and the
other that runs on a PC in some other location with good Internet access.
With this arrangement, the laptop need only establish a single, outbound
Internet connection to the PC. Then, the EchoLink software on the laptop
"tunnels" all traffic through this connection to the remote PC, and the PC in
turn establishes all of the necessary peer-to-peer connections to other
EchoLink nodes. In this scenario, the PC is acting as a <i>proxy</i> on
behalf of the laptop.</font></p>
<p><font size="2">EchoLink now offers special software to make this possible. The
proxy software, which is designed specifically for use with EchoLink, is called <b>EchoLink
Proxy</b>. The diagram below illustrates how EchoLink Proxy can be
used.</font></p>
<p><img border="0" src="images/EchoLinkProxyDiagram.gif" width="591" height="257"></p>
<h2><font face="Verdana, Arial, Helvetica"><font size="3">Is EchoLink Proxy
For You?</font></font></h2>
<p><font size="2">Consider setting up EchoLink Proxy <i>only</i> if <i>both </i>of the
following are true:</font></p>
<ol>
<li>
<font size="2">You have a fast, true, dedicated Internet connection at your home or
office, or at some other place to which you have access to a PC, and</font>
<li>
<font size="2">You have "one-way" Internet service at some other location, or you
often travel to such a place, such as an airport lounge, coffee shop, or hotel
room.</font></li>
</ol>
<p><font size="2">Note that EchoLink Proxy will <i>not</i> help if you are simply
having trouble connecting to other stations from your home PC. In fact,
you must first ensure that EchoLink works correctly on the machine on which the
proxy will be installed.</font></p>
<p><font size="2">Also, note that a given EchoLink Proxy can be used by only one
EchoLink client machine at a time, since each logged-in EchoLink node (or its
proxy) must still have a unique public IP address. You can run more than
one instance of EchoLink Proxy on a PC only if the PC has multiple public
Internet addresses, which is uncommon.</font></p>
<p><font size="2">Finally, the proxy PC must be reachable through a static public
Internet address, or a dynamic public address that can easily be determined
remotely.</font></p>
<h2><font face="Verdana, Arial, Helvetica"><font size="3">Disadvantages</font></font></h2>
<p><font size="2">There are two key disadvantages to using EchoLink Proxy versus the
regular EchoLink software:</font></p>
<ol>
<li>
<font size="2">Voice messages are being transferred between the client and proxy
over TCP, rather than UDP. TCP is not designed to handle this type of
data, and tends to magnify any problems with congestion along the path.</font>
<li>
<font size="2">Two computers (and Internet connections) are required, rather than
just one. It is necessary to run the Proxy software continuously on some
remote server.</font></li>
</ol>
<h2><font face="Verdana, Arial, Helvetica"><font size="3"><a name="installation"></a>Installation
Overview</font></font></h2>
<p><font size="2">Here are the overall steps for installing and using the EchoLink
Proxy. For detailed information, see the section that follows.</font></p>
<ol>
<li>
<font size="2">If the proxy PC runs Windows, verify that the ordinary EchoLink
software works correctly on it, and can connect to other stations.
Resolve any firewall issues.</font>
<li>
<font size="2">Be sure the PC has the Java Runtime Environment 1.4 (or above)
installed.</font>
<li>
<font size="2">Download and install the Proxy software on that PC.</font>
<li>
<font size="2">Choose a port and password for the proxy, and edit the proxy
configuration file.</font>
<li>
<font size="2">Start up the proxy software.</font>
<li>
<font size="2">If necessary, configure the router and/or firewall to allow the PC
to accept inbound TCP connections on the proxy port (e.g. 8100).</font>
<li>
<font size="2">On the client computer (e.g. the laptop), download and install
Version 1.9 of the EchoLink software. This version of the software has a
Proxy option.</font>
<li>
<font size="2">Configure the EchoLink software to connect to the new Proxy
server. You must enter the hostname or address of the proxy PC, the port
number (e.g. 8100), and the chosen password.</font>
<li>
<font size="2">When the EchoLink software starts, it will try to connect to the
Proxy PC. If successful, the program will look and act exactly as it
normally does. When you exit EchoLink, it automatically disconnects from
the Proxy server.</font></li>
</ol>
<h2><font face="Verdana, Arial, Helvetica"><font size="3">Installation
Details</font></font></h2>
<p><font size="2">The EchoLink Proxy software can run on any OS that supports Java,
such as Windows, MacOS, Linux, Solaris, or FreeBSD. </font></p>
<p><font size="2">To verify whether the Java Runtime Environment is installed, and what
version it is, type this command at a command prompt:</font></p>
<p><font size="2" face="Courier New">java -version</font></p>
<p><font size="2">If the command fails, or returns a version lower than 1.4, you will
need to download and install the latest Java Runtime Environment (JRE).
Follow the instructions at:</font></p>
<p><font size="2"><a href="http://www.java.com">www.java.com</a></font></p>
<p><font size="2">Download the EchoLink Proxy software. The download is a ZIP
archive that contains two files. The software is in a file called <font face="Courier New">
EchoLinkProxy.jar</font>, and the sample configuration file is <font face="Courier New">
EchoLinkProxy.conf</font>. Copy both of these files to some
convenient directory or folder on the PC.</font></p>
<p><font size="2">Choose a password and a port number for the EchoLink Proxy. The
default port number is 8100. The port number you choose must be a TCP
port that your home ISP allows for incoming connections, and that the remote
ISP allows for outgoing connections. If you are using security software
on your home PC, you might need to configure it to allow java.exe to accept
connections on this port. Also, if you have a home-networking router, you
will need to configure it to "forward" incoming connections on this TCP port to
the PC on which EchoLink Proxy will be running.</font></p>
<p><font size="2">Using a text editor such as Windows Notepad, edit <font face="Courier New">
EchoLinkProxy.conf</font> to reflect your choices.</font></p>
<p><font size="2">You must also ensure that the proxy PC can accept UDP ports 5198 and
5199, and outbound TCP port 5200. See <a href="firewall_solutions.htm">Firewall
Solutions</a> for details.</font></p>
<p><font size="2">To start the EchoLink Proxy software, open a command prompt, change
to the directory or folder that contains EchoLinkProxy.jar, and type this
command:</font></p>
<p><font face="Courier New" size="2">java -jar EchoLinkProxy.jar</font></p>
<p><font size="2">When the program starts, it will display the message "Ready for new
client connection." Leave the command-prompt window open to allow the
program to keep running.</font></p>
<p><font size="2">On the remote PC (e.g., the laptop), download and install version 1.9
(or above) of the EchoLink software. Start up EchoLink as usual, but go
to Tools-->Setup, and click the Servers tab. Check the box marked "Use
proxy", and enter the hostname (or IP address) of the proxy PC, along with the
chosen password and port number. Note that the hostname (or IP address)
must be the <i>external</i> address of the proxy PC, not the <i>internal</i> address.
Click OK and then re-start EchoLink for the changes to take effect.</font></p>
<p><font size="2">After re-starting EchoLink, if it displays a message about problems
connecting to the proxy, verify that the host name is correct and that no
firewall or router issues are interfering with the TCP connection between
EchoLink and the proxy. (This connection uses <i>only</i> the single TCP
port you selected.)</font></p>
<p><font size="2">If the list of stations appears as usual, but you are unable to
connect to other stations, check the firewall/router setup on the proxy
PC. In effect, the proxy PC is the PC from which EchoLink connections are
established, so all of the information on the <a href="firewall_solutions.htm">Firewall
Solutions</a> page applies to the proxy PC.</font></p>
<p><font size="2">To shut down the proxy, switch to its window and hit Ctrl+C.</font></p>
<h2><font face="Verdana, Arial, Helvetica"><font size="3"><a name="faq"></a>Frequently
Asked Questions</font></font></h2>
<p><font size="3"><b>Q:</b> What version of the EchoLink software will work with
EchoLink Proxy?</font></p>
<blockquote>
<p><font size="2"><b>A:</b> Version 1.9 or above. The new proxy settings appear
on the Servers tab under Tools-->Setup.</font></p>
</blockquote>
<p><font size="3"><b>Q:</b> I have dial-up Internet access at home, rather than
broadband. Can I still use EchoLink Proxy?</font></p>
<blockquote>
<p><font size="2"><b>A:</b> It might work, but it's not recommended. EchoLink
Proxy uses more Internet bandwidth than EchoLink itself requires, which might
be more than your dial-up connection can reliably provide. Also, a
dial-up Internet address usually changes each time the line is re-connected,
making it more difficult for you to establish a connection to it from a remote
PC.</font></p>
</blockquote>
<p><font size="3"><b>Q:</b> What about the remote computer (the one running
EchoLink)? Can it connect to EchoLink Proxy over a dial-up connection?</font></p>
<blockquote>
<p><font size="2"><b>A:</b> Yes, but since it uses the TCP protocol to communicate with
the proxy, packet loss might be more noticeable. However, the proxy is
rarely necessary in this situation since most dial-up accounts provide full
Internet access — you're better off using EchoLink directly.</font></p>
</blockquote>
<p><font size="3"><b>Q:</b> I have a home network with a PC and a laptop, and I've been
having trouble getting EchoLink to work on the laptop. Will this Proxy
thing help?</font></p>
<blockquote>
<p><font size="2"><b>A:</b> It might, but you are probably better off troubleshooting
the laptop problem, since the proxy has certain disadvantages compared to a
direct EchoLink connection.</font></p>
</blockquote>
<p><font size="3"><b>Q:</b> I have broadband Internet access, but my computer's public
IP address changes from time to time. How will I know what its address is
when I am 1,000 miles away?</font></p>
<blockquote>
<p><font size="2"><b>A:</b> There are two solutions (choose one or the other):</font></p>
<ol>
<li>
<font size="2">Subscribe to a "dynamic DNS" service such as <a href="http://www.d2g.com/">
DNS2Go</a>. With the help of special software installed on the PC,
your PC will be assigned a fixed hostname, even though its IP address may
change from time to time.</font>
<li>
<font size="2">Enable the RegistrationName feature in the proxy configuration
file. This will cause the proxy to periodically post a message to the
EchoLink server advising it of your current IP address. You can then find
out the IP address from a special <a href="proxylookup.jsp">web page</a>, which
you can bring up each time you need to connect to the proxy.</font></li>
</ol>
</blockquote>
<p><font size="3"><b>Q:</b> I run a full-time EchoLink Sysop node at home, on my
broadband Internet connection. Can I also run the EchoLink Proxy software
at home, either on the same computer, or on a different one?</font></p>
<blockquote>
<p><font size="2"><b>A:</b> Probably not. The reason is that each EchoLink node
(including the proxy) must have a different public IP address; on most home
networks, a single public Internet address is shared by all computers on the
network. You can do this only if you have made special arrangements with
your ISP to have multiple public Internet addresses.</font></p>
</blockquote>
<p><font size="3"><b>Q:</b> If I use EchoLink (via the proxy) from a public "hotspot",
such as an airport lounge, is there a security risk since others might "sniff"
the information going to and from my laptop?</font></p>
<blockquote>
<p><font size="2"><b>A:</b> This is an important issue that is often overlooked by
users of wireless networks. EchoLink (version 1.8 and above) uses
public-key cryptography to encrypt your login information, and EchoLink Proxy
uses a challenge-response digest-based authentication mechanism.
Passwords are never sent "in the clear". These features help ensure
security over a shared public network.</font></p>
</blockquote>
<p><font size="3"><b>Q:</b> I've tried using the Proxy and it seems to work, except
that I can't connect to any other stations. What is the problem?</font></p>
<blockquote>
<p><font size="2"><b>A:</b> Most likely, it's a firewall or router problem at the proxy
PC (not the EchoLink PC). See <a href="firewall_solutions.htm">Firewall
Solutions</a> for assistance.</font></p>
</blockquote>
<p><font size="3"><b>Q:</b> If my Internet connection is dropped while I'm using the
proxy, can I re-connect?</font></p>
<blockquote>
<p><font size="2"><b>A:</b> In most cases, EchoLink Proxy will detect the dropped
connection and re-set itself right away. In other cases, it may take up
to 10 minutes for the proxy to re-set itself and prepare for a new connection.</font></p>
</blockquote>
<p><font size="3"><b>Q:</b> Can more than one EchoLink user work through my proxy at
the same time?</font></p>
<blockquote>
<p><font size="2"><b>A:</b> No; each instance of the proxy supports only one client at
a time. This is because each logged-on EchoLink user must have a
different public IP address. However, two (or more) users can take turns
using your proxy at <i>different</i> times.</font></p>
</blockquote>
<p><font size="3"><b>Q:</b> When connected through the proxy, will EchoLink support
conferencing?</font></p>
<blockquote>
<p><font size="2"><b>A:</b> Yes, but it is less efficient, since the EchoLink client is
hosting the conference, not the proxy. When calculating the maximum
number of connections you can support, you must consider both the proxy's
upstream Internet connection and the EchoLink client's upstream Internet
connection, and use the lesser of the two; divide the result (in kbps) by
18. Also, keep in mind that the proxy uses equal amounts of upstream and
downstream bandwidth.</font></p>
</blockquote>
<p><font size="3"><b>Q:</b> Can I set up an EchoLink Proxy for others to use, besides
myself?</font></p>
<blockquote>
<p><font size="2"><b>A:</b> Yes, but you must agree not to charge a fee for access to
it.</font> <font size="2">Note that the Proxy configuration file allows
you to set an accept/deny list of callsigns if you want to restrict access to a
specific group of users.</font></p>
<p><font size="2">In fact, there is an option in the Proxy configuration file that
allows you to "advertise" the server as a "public" proxy, and have it
automatically be listed on a <a href="proxylist.jsp">special page</a> on the
EchoLink Web site.</font></p>
</blockquote>
<p><font size="3"><b>Q:</b> Instead of setting up and running my own EchoLink Proxy,
can I simply connect to someone else's?</font></p>
<blockquote>
<p><font size="2"><b>A:</b> Yes, but you would need to know the address and password of
the proxy, and you would need the owner's permission to use it; or, use a
"public" proxy (<a href="proxylist.jsp">see list</a>). If you decide to
use a public proxy, please be considerate; it is a shared resource, and should
be used only for brief time periods. If you have a need for long-term
access to a proxy, please make arrangements to set up a private proxy for
yourself.</font></p>
</blockquote>
<p><font size="3"><b>Q:</b> I have a home network with two computers that share a DSL
connection to the Internet. I run a full-time EchoLink Sysop node on one
of them. Can I run another copy of EchoLink on the second computer by
pointing it to a proxy at some other location?</font></p>
<blockquote>
<p><font size="2"><b>A:</b> Yes; this will work, because your Sysop node and the
distant proxy server would have two different IP addresses. However,
please be considerate about the use of "public" proxies; use them only for
short periods. If you require long-term access to a proxy, please make
arrangements to use a private proxy, or set one up yourself at some other site
that has Internet access.</font></p>
</blockquote>
<p><font size="3"><b>Q:</b> With EchoLink Proxy, will I be able to run EchoLink on a
computer on a private network that has no gateway to the Internet at all?</font></p>
<blockquote>
<p><font size="2"><b>A:</b> The proxy arrangement still requires that the EchoLink
client software perform DNS lookups for certain Internet hosts (namely, the
addressing servers). If you run the EchoLink client software on a private
network and connect through a proxy as the gateway, you would also need a
caching DNS resolver accessible from the EchoLink client.</font></p>
</blockquote>
<p><font size="3"><b>Q:</b> Is there any way to use EchoLink Proxy with an EchoLink
client that is behind an HTTP proxy?</font></p>
<blockquote>
<p><font size="2"><b>A:</b> Yes, as long as the HTTP proxy supports "tunneling" via the
CONNECT command, and the EchoLink Proxy is running on a port to which the HTTP
proxy allows tunneled connections, such as 443. It also requires that the
HTTP proxy's inactivity timer be no shorter than 6 minutes, or that the
EchoLink client remain connected to another station at all times. To use
this feature, put a slash after the EchoLink Proxy hostname, and then the IP
address and port number of the HTTP proxy, separated by a colon.</font></p>
</blockquote>
<p><font size="3"><b>Q:</b> On a Windows computer, how can I set up the proxy so
that it starts automatically each time Windows is re-started?</font></p>
<blockquote>
<p><font size="2"><b>A:</b> On Windows NT/2000 or above, you can set up the proxy to
run as a Windows Service, using a freeware utility called JavaService (<A href="http://forge.objectweb.org/projects/javaservice/">http://forge.objectweb.org/projects/javaservice/</A>).
Assuming you have put EchoLinkProxy in C:\EchoLinkProxy, and you are running
the Sun 1.4.2 JRE, a typical command to install the service might be (all on
one line):</font></p>
<P><FONT face="Courier New" size="2">javaservice<BR>
-install "EchoLinkProxy"<BR>
"C:\Program Files\Java\j2re1.4.2\bin\client\jvm.dll"<BR>
-Djava.class.path=C:\EchoLinkProxy\EchoLinkProxy.jar<BR>
-start org.echolink.proxy.ELProxy<BR>
-out C:\EchoLinkProxy\stdout.txt<BR>
-current c:\EchoLinkProxy</FONT></P>
</blockquote><a name="status"></a>
<H2><FONT face="Verdana, Arial, Helvetica"><FONT size="3">Status Pages</FONT></FONT></H2>
<p><a href="proxylist.jsp">List of Public EchoLink Proxies</a></p>
<p><font size="2">This page displays the address and current status of each EchoLink
Proxy Server that welcomes access from any EchoLink user.</font></p>
<p><a href="proxylookup.jsp">EchoLink Proxy Lookup</a></p>
<p><font size="2">Looks up the current Internet address of any proxy server (public or
private) that has registered itself using the RegistrationName option.
See the comments in the EchoLink Proxy configuration file for details.</font></p>
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<p align="center"><font size="1">Copyright © 2002-2015 Synergenics, LLC.
EchoLink<sup>®</sup> is a registered trademark of Synergenics, LLC.</font></p>
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