1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
|
<html>
<head>
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<meta http-equiv="Content-Language" content="en" />
<title>s6-networking: the s6-tlsserver program</title>
<meta name="Description" content="s6-networking: the s6-tlsserver program" />
<meta name="Keywords" content="s6-networking s6-tlsclient tlsserver tls ssl ucspi tcp inet network tcp/ip server superserver" />
<!-- <link rel="stylesheet" type="text/css" href="//skarnet.org/default.css" /> -->
</head>
<body>
<p>
<a href="index.html">s6-networking</a><br />
<a href="//skarnet.org/software/">Software</a><br />
<a href="//skarnet.org/">skarnet.org</a>
</p>
<h1> The <tt>s6-tlsserver</tt> program </h1>
<p>
<tt>s6-tlsserver</tt> is an
<a href="https://cr.yp.to/proto/ucspi.txt">UCSPI server tool</a> for
TLS/SSL connections over INET domain sockets. It acts as a TCP super-server
that listens to connections, accepts them, and for each connection,
establishes a TLS transport over it, then executes into a program.
</p>
<h2> Interface </h2>
<pre>
s6-tlsserver [ <em>options</em> ] [ -- ] <em>ip</em> <em>port</em> <em>prog...</em>
</pre>
<ul>
<li> s6-tlsserver rewrites itself into a command line
involving:
<ul>
<li> <a href="s6-tcpserver.html">s6-tcpserver</a>, which
listens to TCP connections on IP address <em>ip</em> port <em>port</em>
and forks a command line for every connection. Note that
<a href="s6-tcpserver.html">s6-tcpserver</a> also rewrites
itself into a more complex command line (the final long-lived
process being <a href="s6-tcpserver4d.html">s6-tcpserver4d</a>
or <a href="s6-tcpserver4d.html">s6-tcpserver6d</a>),
so your end command line may look a lot longer in <tt>ps</tt>
than what you originally wrote. This is normal and healthy. </li>
<li> (if applicable) <a href="s6-tcpserver-access.html">s6-tcpserver-access</a>,
which performs TCP access control and various operations on the
TCP connection. </li>
<li> <a href="s6-tlsd.html">s6-tlsd</a>, which establishes
a TLS transport (server-side) over a connection, via an
<a href="s6-tlsd-io.html">s6-tlsd-io</a> child process. </li>
<li> (if applicable)
<a href="//skarnet.org/software/s6/s6-applyuidgid.html">s6-applyuidgid</a>,
which drops root privileges. </li>
<li> <em>prog...</em>, your client program, which is run with the
same pid as <a href="s6-tlsd.html">s6-tlsd</a>. </li>
</ul> </li>
<li> It runs until it is killed by a signal. </li>
</ul>
<p>
<em>prog</em> is expected to read from its peer on its
standard input and write to its peer on its standard output.
Since there will be an <a href="s6-tlsd-io.html">s6-tlsd-io</a>
program between <em>prog</em> and the network to perform
the SSL encryption/decryption, those descriptors will not
be a network socket - they will be pipes.
</p>
<h2> Signals </h2>
<p>
<tt>s6-tlsserver</tt> reacts to the same signals as
<a href="s6-tcpserver4d.html">s6-tcpserver4d</a> or
<a href="s6-tcpserver6d.html">s6-tcpserver6d</a>,
one of which is the long-lived process hanging around.
</p>
<h2> Environment variables </h2>
<h3> Read </h3>
<p>
The following variables should be set before invoking
<tt>s6-tlsserver</tt>, because they will be used by
every <a href="s6-tlsd.html">s6-tlsd</a> invocation:
</p>
<ul>
<li> KEYFILE </li>
<li> CERTFILE </li>
<li> TLS_UID and TLS_GID (if you run <tt>s6-tlsserver</tt> as root) </li>
<li> CADIR (if you want client certificates) </li>
<li> CAFILE (if you want client certificates, alternative to CADIR) </li>
</ul>
<p>
Setting both KEYFILE and CERTFILE is mandatory.
</p>
<h3> Written </h3>
<p>
<em>prog...</em> is run with the following variables added to,
or removed from, its environment by <a href="s6-tcpserver4d.html">s6-tcpserver4d</a>
or <a href="s6-tcpserver6d.html">s6-tcpserver6d</a>, and possibly
by <a href="s6-tcpserver-access.html">s6-tcpserver-access</a>:
</p>
<ul>
<li> PROTO </li>
<li> TCPREMOTEIP </li>
<li> TCPREMOTEPORT </li>
<li> TCPCONNNUM </li>
<li> TCPLOCALIP </li>
<li> TCPLOCALPORT </li>
<li> TCPREMOTEHOST </li>
<li> TCPLOCALHOST </li>
<li> TCPREMOTEINFO </li>
</ul>
<p>
Depending on TCP access rules (if the <tt>-i</tt> or <tt>-x</tt>
option has been given), it is possible that <em>prog</em>'s
environment undergoes more modifications. Also, since
<a href="s6-tlsd.html">s6-tlsd</a> is always run
after <a href="s6-tcpserver-access.html">s6-tcpserver-access</a>,
it is possible to set different TLS/SSL parameters (typically
a different KEYFILE and CERTFILE) depending on the client
connection, by writing the correct set of TCP access rules.
</p>
<p>
Unless the <tt>-Z</tt> option is given to <tt>s6-tlsserver</tt>,
the CADIR, CAFILE, KEYFILE, CERTFILE, TLS_UID and TLS_GID
variables will not appear in <em>prog</em>'s environment.
</p>
<h2> Options </h2>
<p>
<tt>s6-tlsserver</tt> accepts a myriad of options, most of which are
passed as is to the correct executable. Not giving any options will
generally work, but unless you're running a very public server
(such as a Web server) or base your access control on client
certificates, you probably still want TCP access rules.
</p>
<h3> Options handled directly by s6-tlsserver </h3>
<ul>
<li> <tt>-e</tt>: : indicates that
<a href="s6-tcpserver-access.html">s6-tcpserver-access</a> should
be invoked, even if no other option requires it, even in the absence
of an access control ruleset. This ensures that <em>prog...</em>
will always have access to environment variables such as TCPLOCALPORT. </li>
</ul>
<h3> Options passed as is to s6-tcpserver </h3>
<ul>
<li> <tt>-q</tt>, <tt>-Q</tt>, <tt>-v</tt> </li>
<li> <tt>-4</tt>, <tt>-6</tt> </li>
<li> <tt>-1</tt> </li>
<li> <tt>-c <em>maxconn</em></tt> </li>
<li> <tt>-C <em>localmaxconn</em></tt> </li>
<li> <tt>-b <em>backlog</em></tt> </li>
</ul>
<h3> Options passed as is to s6-tcpserver-access </h3>
<ul>
<li> The verbosity level, if not default, as <tt>-v0</tt> or <tt>-v2</tt> </li>
<li> <tt>-w</tt>, <tt>-W</tt> </li>
<li> <tt>-d</tt>, <tt>-D</tt> </li>
<li> <tt>-r</tt>, <tt>-R</tt> </li>
<li> <tt>-p</tt>, <tt>-P</tt> </li>
<li> <tt>-h</tt>, <tt>-H</tt>, <tt>-l <em>localname</em></tt> </li>
<li> <tt>-B <em>banner</em></tt> </li>
<li> <tt>-t <em>timeout</em></tt> </li>
<li> <tt>-i <em>rulesdir</em></tt>, <tt>-x <em>rulesfile</em></tt> </li>
</ul>
<h3> Options passed as is to s6-tlsd </h3>
<ul>
<li> <tt>-Z</tt>, <tt>-z</tt> </li>
<li> <tt>-S</tt>, <tt>-s</tt> </li>
<li> <tt>-Y</tt>, <tt>-y</tt> </li>
<li> <tt>-K <em>kimeout</em></tt> </li>
<li> <tt>-k <em>snilevel</em></tt> </li>
</ul>
<h3> Options passed to s6-applyuidgid </h3>
<ul>
<li> <tt>-u <em>uid</em></tt>, <tt>-g <em>gid</em></tt>, <tt>-G <em>gidlist</em></tt> </li>
<li> <tt>-U</tt> (passed as <tt>-Uz</tt>) </li>
</ul>
<h2> Example </h2>
<p>
As root:
</p>
<pre>env KEYFILE=/etc/ssl/private/mykey.der CERTFILE=/etc/ssl/public/mycert.pem \
TLS_UID=65534 TLS_UID=65534 \
s6-envuidgid www \
s6-tlsserver -U -- 1.2.3.4 443 httpd</pre>
<p>
This will start a server listening to 1.2.3.4 on TCP port 443,
and for every connection, spawn the <tt>httpd</tt> program
reading queries on stdin and replying on stdout, as user <tt>www</tt>,
with a TLS layer protecting the connection, the TLS engine running
as user <tt>nobody</tt> (<tt>65534:65534</tt>). The server is
authenticated by the certificate in <tt>/etc/ssl/public/mycert.pem</tt>
that it sends to the client, and the private key in
<tt>/etc/ssl/private/mykey.der</tt> that it keeps to itself.
</p>
</body>
</html>
|
