Initial import from FreeBSD RELENG_4:
[dragonfly.git] / secure / lib / libssl / man / SSL_CTX_set_options.3
CommitLineData
984263bc
MD
1.\" Automatically generated by Pod::Man version 1.15
2.\" Wed Feb 19 16:47:41 2003
3.\"
4.\" Standard preamble:
5.\" ======================================================================
6.de Sh \" Subsection heading
7.br
8.if t .Sp
9.ne 5
10.PP
11\fB\\$1\fR
12.PP
13..
14.de Sp \" Vertical space (when we can't use .PP)
15.if t .sp .5v
16.if n .sp
17..
18.de Ip \" List item
19.br
20.ie \\n(.$>=3 .ne \\$3
21.el .ne 3
22.IP "\\$1" \\$2
23..
24.de Vb \" Begin verbatim text
25.ft CW
26.nf
27.ne \\$1
28..
29.de Ve \" End verbatim text
30.ft R
31
32.fi
33..
34.\" Set up some character translations and predefined strings. \*(-- will
35.\" give an unbreakable dash, \*(PI will give pi, \*(L" will give a left
36.\" double quote, and \*(R" will give a right double quote. | will give a
37.\" real vertical bar. \*(C+ will give a nicer C++. Capital omega is used
38.\" to do unbreakable dashes and therefore won't be available. \*(C` and
39.\" \*(C' expand to `' in nroff, nothing in troff, for use with C<>
40.tr \(*W-|\(bv\*(Tr
41.ds C+ C\v'-.1v'\h'-1p'\s-2+\h'-1p'+\s0\v'.1v'\h'-1p'
42.ie n \{\
43. ds -- \(*W-
44. ds PI pi
45. if (\n(.H=4u)&(1m=24u) .ds -- \(*W\h'-12u'\(*W\h'-12u'-\" diablo 10 pitch
46. if (\n(.H=4u)&(1m=20u) .ds -- \(*W\h'-12u'\(*W\h'-8u'-\" diablo 12 pitch
47. ds L" ""
48. ds R" ""
49. ds C` ""
50. ds C' ""
51'br\}
52.el\{\
53. ds -- \|\(em\|
54. ds PI \(*p
55. ds L" ``
56. ds R" ''
57'br\}
58.\"
59.\" If the F register is turned on, we'll generate index entries on stderr
60.\" for titles (.TH), headers (.SH), subsections (.Sh), items (.Ip), and
61.\" index entries marked with X<> in POD. Of course, you'll have to process
62.\" the output yourself in some meaningful fashion.
63.if \nF \{\
64. de IX
65. tm Index:\\$1\t\\n%\t"\\$2"
66..
67. nr % 0
68. rr F
69.\}
70.\"
71.\" For nroff, turn off justification. Always turn off hyphenation; it
72.\" makes way too many mistakes in technical documents.
73.hy 0
74.if n .na
75.\"
76.\" Accent mark definitions (@(#)ms.acc 1.5 88/02/08 SMI; from UCB 4.2).
77.\" Fear. Run. Save yourself. No user-serviceable parts.
78.bd B 3
79. \" fudge factors for nroff and troff
80.if n \{\
81. ds #H 0
82. ds #V .8m
83. ds #F .3m
84. ds #[ \f1
85. ds #] \fP
86.\}
87.if t \{\
88. ds #H ((1u-(\\\\n(.fu%2u))*.13m)
89. ds #V .6m
90. ds #F 0
91. ds #[ \&
92. ds #] \&
93.\}
94. \" simple accents for nroff and troff
95.if n \{\
96. ds ' \&
97. ds ` \&
98. ds ^ \&
99. ds , \&
100. ds ~ ~
101. ds /
102.\}
103.if t \{\
104. ds ' \\k:\h'-(\\n(.wu*8/10-\*(#H)'\'\h"|\\n:u"
105. ds ` \\k:\h'-(\\n(.wu*8/10-\*(#H)'\`\h'|\\n:u'
106. ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'^\h'|\\n:u'
107. ds , \\k:\h'-(\\n(.wu*8/10)',\h'|\\n:u'
108. ds ~ \\k:\h'-(\\n(.wu-\*(#H-.1m)'~\h'|\\n:u'
109. ds / \\k:\h'-(\\n(.wu*8/10-\*(#H)'\z\(sl\h'|\\n:u'
110.\}
111. \" troff and (daisy-wheel) nroff accents
112.ds : \\k:\h'-(\\n(.wu*8/10-\*(#H+.1m+\*(#F)'\v'-\*(#V'\z.\h'.2m+\*(#F'.\h'|\\n:u'\v'\*(#V'
113.ds 8 \h'\*(#H'\(*b\h'-\*(#H'
114.ds o \\k:\h'-(\\n(.wu+\w'\(de'u-\*(#H)/2u'\v'-.3n'\*(#[\z\(de\v'.3n'\h'|\\n:u'\*(#]
115.ds d- \h'\*(#H'\(pd\h'-\w'~'u'\v'-.25m'\f2\(hy\fP\v'.25m'\h'-\*(#H'
116.ds D- D\\k:\h'-\w'D'u'\v'-.11m'\z\(hy\v'.11m'\h'|\\n:u'
117.ds th \*(#[\v'.3m'\s+1I\s-1\v'-.3m'\h'-(\w'I'u*2/3)'\s-1o\s+1\*(#]
118.ds Th \*(#[\s+2I\s-2\h'-\w'I'u*3/5'\v'-.3m'o\v'.3m'\*(#]
119.ds ae a\h'-(\w'a'u*4/10)'e
120.ds Ae A\h'-(\w'A'u*4/10)'E
121. \" corrections for vroff
122.if v .ds ~ \\k:\h'-(\\n(.wu*9/10-\*(#H)'\s-2\u~\d\s+2\h'|\\n:u'
123.if v .ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'\v'-.4m'^\v'.4m'\h'|\\n:u'
124. \" for low resolution devices (crt and lpr)
125.if \n(.H>23 .if \n(.V>19 \
126\{\
127. ds : e
128. ds 8 ss
129. ds o a
130. ds d- d\h'-1'\(ga
131. ds D- D\h'-1'\(hy
132. ds th \o'bp'
133. ds Th \o'LP'
134. ds ae ae
135. ds Ae AE
136.\}
137.rm #[ #] #H #V #F C
138.\" ======================================================================
139.\"
140.IX Title "SSL_CTX_set_options 3"
141.TH SSL_CTX_set_options 3 "0.9.7a" "2003-02-19" "OpenSSL"
142.UC
143.SH "NAME"
144SSL_CTX_set_options, SSL_set_options, SSL_CTX_get_options, SSL_get_options \- manipulate \s-1SSL\s0 engine options
145.SH "SYNOPSIS"
146.IX Header "SYNOPSIS"
147.Vb 1
148\& #include <openssl/ssl.h>
149.Ve
150.Vb 2
151\& long SSL_CTX_set_options(SSL_CTX *ctx, long options);
152\& long SSL_set_options(SSL *ssl, long options);
153.Ve
154.Vb 2
155\& long SSL_CTX_get_options(SSL_CTX *ctx);
156\& long SSL_get_options(SSL *ssl);
157.Ve
158.SH "DESCRIPTION"
159.IX Header "DESCRIPTION"
160\&\fISSL_CTX_set_options()\fR adds the options set via bitmask in \fBoptions\fR to \fBctx\fR.
161Options already set before are not cleared!
162.PP
163\&\fISSL_set_options()\fR adds the options set via bitmask in \fBoptions\fR to \fBssl\fR.
164Options already set before are not cleared!
165.PP
166\&\fISSL_CTX_get_options()\fR returns the options set for \fBctx\fR.
167.PP
168\&\fISSL_get_options()\fR returns the options set for \fBssl\fR.
169.SH "NOTES"
170.IX Header "NOTES"
171The behaviour of the \s-1SSL\s0 library can be changed by setting several options.
172The options are coded as bitmasks and can be combined by a logical \fBor\fR
173operation (|). Options can only be added but can never be reset.
174.PP
175\&\fISSL_CTX_set_options()\fR and \fISSL_set_options()\fR affect the (external)
176protocol behaviour of the \s-1SSL\s0 library. The (internal) behaviour of
177the \s-1API\s0 can be changed by using the similar
178SSL_CTX_set_mode(3) and \fISSL_set_mode()\fR functions.
179.PP
180During a handshake, the option settings of the \s-1SSL\s0 object are used. When
181a new \s-1SSL\s0 object is created from a context using \fISSL_new()\fR, the current
182option setting is copied. Changes to \fBctx\fR do not affect already created
183\&\s-1SSL\s0 objects. \fISSL_clear()\fR does not affect the settings.
184.PP
185The following \fBbug workaround\fR options are available:
186.Ip "\s-1SSL_OP_MICROSOFT_SESS_ID_BUG\s0" 4
187.IX Item "SSL_OP_MICROSOFT_SESS_ID_BUG"
188www.microsoft.com \- when talking SSLv2, if session-id reuse is
189performed, the session-id passed back in the server-finished message
190is different from the one decided upon.
191.Ip "\s-1SSL_OP_NETSCAPE_CHALLENGE_BUG\s0" 4
192.IX Item "SSL_OP_NETSCAPE_CHALLENGE_BUG"
193Netscape-Commerce/1.12, when talking SSLv2, accepts a 32 byte
194challenge but then appears to only use 16 bytes when generating the
195encryption keys. Using 16 bytes is ok but it should be ok to use 32.
196According to the SSLv3 spec, one should use 32 bytes for the challenge
197when operating in SSLv2/v3 compatibility mode, but as mentioned above,
198this breaks this server so 16 bytes is the way to go.
199.Ip "\s-1SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG\s0" 4
200.IX Item "SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG"
201ssl3.netscape.com:443, first a connection is established with \s-1RC4\-MD5\s0.
202If it is then resumed, we end up using \s-1DES-CBC3\-SHA\s0. It should be
203\&\s-1RC4\-MD5\s0 according to 7.6.1.3, 'cipher_suite'.
204.Sp
205Netscape-Enterprise/2.01 (https://merchant.netscape.com) has this bug.
206It only really shows up when connecting via SSLv2/v3 then reconnecting
207via SSLv3. The cipher list changes....
208.Sp
209\&\s-1NEW\s0 \s-1INFORMATION\s0. Try connecting with a cipher list of just
210\&\s-1DES-CBC-SHA:RC4\-MD5\s0. For some weird reason, each new connection uses
211\&\s-1RC4\-MD5\s0, but a re-connect tries to use \s-1DES-CBC-SHA\s0. So netscape, when
212doing a re-connect, always takes the first cipher in the cipher list.
213.Ip "\s-1SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG\s0" 4
214.IX Item "SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG"
215\&...
216.Ip "\s-1SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER\s0" 4
217.IX Item "SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER"
218\&...
219.Ip "\s-1SSL_OP_MSIE_SSLV2_RSA_PADDING\s0" 4
220.IX Item "SSL_OP_MSIE_SSLV2_RSA_PADDING"
221\&...
222.Ip "\s-1SSL_OP_SSLEAY_080_CLIENT_DH_BUG\s0" 4
223.IX Item "SSL_OP_SSLEAY_080_CLIENT_DH_BUG"
224\&...
225.Ip "\s-1SSL_OP_TLS_D5_BUG\s0" 4
226.IX Item "SSL_OP_TLS_D5_BUG"
227\&...
228.Ip "\s-1SSL_OP_TLS_BLOCK_PADDING_BUG\s0" 4
229.IX Item "SSL_OP_TLS_BLOCK_PADDING_BUG"
230\&...
231.Ip "\s-1SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS\s0" 4
232.IX Item "SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS"
233Disables a countermeasure against a \s-1SSL\s0 3.0/TLS 1.0 protocol
234vulnerability affecting \s-1CBC\s0 ciphers, which cannot be handled by some
235broken \s-1SSL\s0 implementations. This option has no effect for connections
236using other ciphers.
237.Ip "\s-1SSL_OP_ALL\s0" 4
238.IX Item "SSL_OP_ALL"
239All of the above bug workarounds.
240.PP
241It is usually safe to use \fB\s-1SSL_OP_ALL\s0\fR to enable the bug workaround
242options if compatibility with somewhat broken implementations is
243desired.
244.PP
245The following \fBmodifying\fR options are available:
246.Ip "\s-1SSL_OP_TLS_ROLLBACK_BUG\s0" 4
247.IX Item "SSL_OP_TLS_ROLLBACK_BUG"
248Disable version rollback attack detection.
249.Sp
250During the client key exchange, the client must send the same information
251about acceptable \s-1SSL/TLS\s0 protocol levels as during the first hello. Some
252clients violate this rule by adapting to the server's answer. (Example:
253the client sends a SSLv2 hello and accepts up to SSLv3.1=TLSv1, the server
254only understands up to SSLv3. In this case the client must still use the
255same SSLv3.1=TLSv1 announcement. Some clients step down to SSLv3 with respect
256to the server's answer and violate the version rollback protection.)
257.Ip "\s-1SSL_OP_SINGLE_DH_USE\s0" 4
258.IX Item "SSL_OP_SINGLE_DH_USE"
259Always create a new key when using temporary/ephemeral \s-1DH\s0 parameters
260(see SSL_CTX_set_tmp_dh_callback(3)).
261This option must be used to prevent small subgroup attacks, when
262the \s-1DH\s0 parameters were not generated using \*(L"strong\*(R" primes
263(e.g. when using DSA-parameters, see dhparam(1)).
264If \*(L"strong\*(R" primes were used, it is not strictly necessary to generate
265a new \s-1DH\s0 key during each handshake but it is also recommended.
266\&\fB\s-1SSL_OP_SINGLE_DH_USE\s0\fR should therefore be enabled whenever
267temporary/ephemeral \s-1DH\s0 parameters are used.
268.Ip "\s-1SSL_OP_EPHEMERAL_RSA\s0" 4
269.IX Item "SSL_OP_EPHEMERAL_RSA"
270Always use ephemeral (temporary) \s-1RSA\s0 key when doing \s-1RSA\s0 operations
271(see SSL_CTX_set_tmp_rsa_callback(3)).
272According to the specifications this is only done, when a \s-1RSA\s0 key
273can only be used for signature operations (namely under export ciphers
274with restricted \s-1RSA\s0 keylength). By setting this option, ephemeral
275\&\s-1RSA\s0 keys are always used. This option breaks compatibility with the
276\&\s-1SSL/TLS\s0 specifications and may lead to interoperability problems with
277clients and should therefore never be used. Ciphers with \s-1EDH\s0 (ephemeral
278Diffie-Hellman) key exchange should be used instead.
279.Ip "\s-1SSL_OP_CIPHER_SERVER_PREFERENCE\s0" 4
280.IX Item "SSL_OP_CIPHER_SERVER_PREFERENCE"
281When choosing a cipher, use the server's preferences instead of the client
282preferences. When not set, the \s-1SSL\s0 server will always follow the clients
283preferences. When set, the SSLv3/TLSv1 server will choose following its
284own preferences. Because of the different protocol, for SSLv2 the server
285will send his list of preferences to the client and the client chooses.
286.Ip "\s-1SSL_OP_PKCS1_CHECK_1\s0" 4
287.IX Item "SSL_OP_PKCS1_CHECK_1"
288\&...
289.Ip "\s-1SSL_OP_PKCS1_CHECK_2\s0" 4
290.IX Item "SSL_OP_PKCS1_CHECK_2"
291\&...
292.Ip "\s-1SSL_OP_NETSCAPE_CA_DN_BUG\s0" 4
293.IX Item "SSL_OP_NETSCAPE_CA_DN_BUG"
294If we accept a netscape connection, demand a client cert, have a
295non-self-sighed \s-1CA\s0 which does not have it's \s-1CA\s0 in netscape, and the
296browser has a cert, it will crash/hang. Works for 3.x and 4.xbeta
297.Ip "\s-1SSL_OP_NETSCAPE_DEMO_CIPHER_CHANGE_BUG\s0" 4
298.IX Item "SSL_OP_NETSCAPE_DEMO_CIPHER_CHANGE_BUG"
299\&...
300.Ip "SSL_OP_NO_SSLv2" 4
301.IX Item "SSL_OP_NO_SSLv2"
302Do not use the SSLv2 protocol.
303.Ip "SSL_OP_NO_SSLv3" 4
304.IX Item "SSL_OP_NO_SSLv3"
305Do not use the SSLv3 protocol.
306.Ip "SSL_OP_NO_TLSv1" 4
307.IX Item "SSL_OP_NO_TLSv1"
308Do not use the TLSv1 protocol.
309.Ip "\s-1SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION\s0" 4
310.IX Item "SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION"
311When performing renegotiation as a server, always start a new session
312(i.e., session resumption requests are only accepted in the initial
313handshake). This option is not needed for clients.
314.SH "RETURN VALUES"
315.IX Header "RETURN VALUES"
316\&\fISSL_CTX_set_options()\fR and \fISSL_set_options()\fR return the new options bitmask
317after adding \fBoptions\fR.
318.PP
319\&\fISSL_CTX_get_options()\fR and \fISSL_get_options()\fR return the current bitmask.
320.SH "SEE ALSO"
321.IX Header "SEE ALSO"
322ssl(3), SSL_new(3), SSL_clear(3),
323SSL_CTX_set_tmp_dh_callback(3),
324SSL_CTX_set_tmp_rsa_callback(3),
325dhparam(1)
326.SH "HISTORY"
327.IX Header "HISTORY"
328\&\fB\s-1SSL_OP_CIPHER_SERVER_PREFERENCE\s0\fR and
329\&\fB\s-1SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION\s0\fR have been added in
330OpenSSL 0.9.7.
331.PP
332\&\fB\s-1SSL_OP_TLS_ROLLBACK_BUG\s0\fR has been added in OpenSSL 0.9.6 and was automatically
333enabled with \fB\s-1SSL_OP_ALL\s0\fR. As of 0.9.7, it is no longer included in \fB\s-1SSL_OP_ALL\s0\fR
334and must be explicitly set.
335.PP
336\&\fB\s-1SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS\s0\fR has been added in OpenSSL 0.9.6e.
337Versions up to OpenSSL 0.9.6c do not include the countermeasure that
338can be disabled with this option (in OpenSSL 0.9.6d, it was always
339enabled).