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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>19.11. Secure TCP/IP Connections with SSH Tunnels</title><link rel="stylesheet" type="text/css" href="stylesheet.css" /><link rev="made" href="pgsql-docs@lists.postgresql.org" /><meta name="generator" content="DocBook XSL Stylesheets Vsnapshot" /><link rel="prev" href="gssapi-enc.html" title="19.10. Secure TCP/IP Connections with GSSAPI Encryption" /><link rel="next" href="event-log-registration.html" title="19.12. Registering Event Log on Windows" /></head><body id="docContent" class="container-fluid col-10"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">19.11. Secure TCP/IP Connections with <span class="application">SSH</span> Tunnels</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="gssapi-enc.html" title="19.10. Secure TCP/IP Connections with GSSAPI Encryption">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="runtime.html" title="Chapter 19. Server Setup and Operation">Up</a></td><th width="60%" align="center">Chapter 19. Server Setup and Operation</th><td width="10%" align="right"><a accesskey="h" href="index.html" title="PostgreSQL 16.3 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="event-log-registration.html" title="19.12. Registering Event Log on Windows">Next</a></td></tr></table><hr /></div><div class="sect1" id="SSH-TUNNELS"><div class="titlepage"><div><div><h2 class="title" style="clear: both">19.11. Secure TCP/IP Connections with <span class="application">SSH</span> Tunnels <a href="#SSH-TUNNELS" class="id_link">#</a></h2></div></div></div><a id="id-1.6.6.14.2" class="indexterm"></a><p>
It is possible to use <span class="application">SSH</span> to encrypt the network
connection between clients and a
<span class="productname">PostgreSQL</span> server. Done properly, this
provides an adequately secure network connection, even for non-SSL-capable
clients.
</p><p>
First make sure that an <span class="application">SSH</span> server is
running properly on the same machine as the
<span class="productname">PostgreSQL</span> server and that you can log in using
<code class="command">ssh</code> as some user; you then can establish a
secure tunnel to the remote server. A secure tunnel listens on a
local port and forwards all traffic to a port on the remote machine.
Traffic sent to the remote port can arrive on its
<code class="literal">localhost</code> address, or different bind
address if desired; it does not appear as coming from your
local machine. This command creates a secure tunnel from the client
machine to the remote machine <code class="literal">foo.com</code>:
</p><pre class="programlisting">
ssh -L 63333:localhost:5432 joe@foo.com
</pre><p>
The first number in the <code class="option">-L</code> argument, 63333, is the
local port number of the tunnel; it can be any unused port. (IANA
reserves ports 49152 through 65535 for private use.) The name or IP
address after this is the remote bind address you are connecting to,
i.e., <code class="literal">localhost</code>, which is the default. The second
number, 5432, is the remote end of the tunnel, e.g., the port number
your database server is using. In order to connect to the database
server using this tunnel, you connect to port 63333 on the local
machine:
</p><pre class="programlisting">
psql -h localhost -p 63333 postgres
</pre><p>
To the database server it will then look as though you are
user <code class="literal">joe</code> on host <code class="literal">foo.com</code>
connecting to the <code class="literal">localhost</code> bind address, and it
will use whatever authentication procedure was configured for
connections by that user to that bind address. Note that the server will not
think the connection is SSL-encrypted, since in fact it is not
encrypted between the
<span class="application">SSH</span> server and the
<span class="productname">PostgreSQL</span> server. This should not pose any
extra security risk because they are on the same machine.
</p><p>
In order for the
tunnel setup to succeed you must be allowed to connect via
<code class="command">ssh</code> as <code class="literal">joe@foo.com</code>, just
as if you had attempted to use <code class="command">ssh</code> to create a
terminal session.
</p><p>
You could also have set up port forwarding as
</p><pre class="programlisting">
ssh -L 63333:foo.com:5432 joe@foo.com
</pre><p>
but then the database server will see the connection as coming in
on its <code class="literal">foo.com</code> bind address, which is not opened by
the default setting <code class="literal">listen_addresses =
'localhost'</code>. This is usually not what you want.
</p><p>
If you have to <span class="quote">“<span class="quote">hop</span>”</span> to the database server via some
login host, one possible setup could look like this:
</p><pre class="programlisting">
ssh -L 63333:db.foo.com:5432 joe@shell.foo.com
</pre><p>
Note that this way the connection
from <code class="literal">shell.foo.com</code>
to <code class="literal">db.foo.com</code> will not be encrypted by the SSH
tunnel.
SSH offers quite a few configuration possibilities when the network
is restricted in various ways. Please refer to the SSH
documentation for details.
</p><div class="tip"><h3 class="title">Tip</h3><p>
Several other applications exist that can provide secure tunnels using
a procedure similar in concept to the one just described.
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