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Bryan Henderson's fine update of SSL_VERIFYPEER and SSL_VERIFYHOST

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Daniel Stenberg 2005-05-02 07:28:40 +00:00
parent 4be2136de4
commit d12b44204b
1 changed files with 74 additions and 18 deletions
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92
docs/libcurl/curl_easy_setopt.3
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@ -999,25 +999,52 @@ operations.
Pass a long as parameter. Set what version of SSL to attempt to use, 2 or
3. By default, the SSL library will try to solve this by itself although some
servers make this difficult why you at times may have to use this option.
.IP CURLOPT_SSL_VERIFYPEER
Pass a long that is set to a zero value to stop curl from verifying the peer's
certificate (7.10 starting setting this option to non-zero by default).
Alternate certificates to verify against can be specified with the
\fICURLOPT_CAINFO\fP option or a certificate directory can be specified with
the \fICURLOPT_CAPATH\fP option. As of 7.10, curl installs a default bundle.
\fICURLOPT_SSL_VERIFYHOST\fP may also need to be set to 1 or 0 if
\fICURLOPT_SSL_VERIFYPEER\fP is disabled (it defaults to 2).
Pass a long as parameter.
This option determines whether curl verifies the authenticity of the
peer's certificate. A nonzero value means curl verifies; zero means it
doesn't. The default is nonzero, but before 7.10, it was zero.
When negotiating an SSL connection, the server sends a certificate
indicating its identity. Curl verifies whether the certificate is
authentic, i.e. that you can trust that the server is who the
certificate says it is. This trust is based on a chain of digital
signatures, rooted in certification authority (CA) certificates you
supply. As of 7.10, curl installs a default bundle of CA certificates
and you can specify alternate certificates with the
\fICURLOPT_CAINFO\fP option or the \fICURLOPT_CAPATH\fP option.
When \fICURLOPT_SSL_VERIFYPEER\fP is nonzero, and the verification
fails to prove that the certificate is authentic, the connection
fails. When the option is zero, the connection succeeds regardless.
Authenticating the certificate is not by itself very useful. You
typically want to ensure that the server, as authentically identified
by its certificate, is the server you mean to be talking to. Use
\fICURLOPT_SSL_VERIFYHOST\fP to control that.
.IP CURLOPT_CAINFO
Pass a char * to a zero terminated string naming a file holding one or more
certificates to verify the peer with. This only makes sense when used in
combination with the \fICURLOPT_SSL_VERIFYPEER\fP option.
certificates to verify the peer with. This makes sense only when used in
combination with the \fICURLOPT_SSL_VERIFYPEER\fP option. If
\fICURLOPT_SSL_VERIFYPEER\fP is zero, \fICURLOPT_CAINFO\fP need not
even indicate an accessible file.
.IP CURLOPT_CAPATH
Pass a char * to a zero terminated string naming a directory holding multiple
CA certificates to verify the peer with. The certificate directory must be
prepared using the openssl c_rehash utility. This only makes sense when used
in combination with the \fICURLOPT_SSL_VERIFYPEER\fP option. The
\fICURLOPT_CAPATH\fP function apparently does not work in Windows due to some
limitation in openssl. (Added in 7.9.8)
Pass a char * to a zero terminated string naming a directory holding
multiple CA certificates to verify the peer with. The certificate
directory must be prepared using the openssl c_rehash utility. This
makes sense only when used in combination with the
\fICURLOPT_SSL_VERIFYPEER\fP option. If \fICURLOPT_SSL_VERIFYPEER\fP
is zero, \fICURLOPT_CAPATH\fP need not even indicate an accessible
path. The \fICURLOPT_CAPATH\fP function apparently does not work in
Windows due to some limitation in openssl. (Added in 7.9.8)
.IP CURLOPT_RANDOM_FILE
Pass a char * to a zero terminated file name. The file will be used to read
from to seed the random engine for SSL. The more random the specified file is,
@ -1025,10 +1052,38 @@ the more secure the SSL connection will become.
.IP CURLOPT_EGDSOCKET
Pass a char * to the zero terminated path name to the Entropy Gathering Daemon
socket. It will be used to seed the random engine for SSL.
.IP CURLOPT_SSL_VERIFYHOST
Pass a long. Set if we should verify the Common name from the peer certificate
in the SSL handshake, set 1 to check existence, 2 to ensure that it matches
the provided hostname. This is by default set to 2. (default changed in 7.10)
Pass a long as parameter.
This option determines whether curl verifies that the server claims to be
who you want it to be.
When negotiating an SSL connection, the server sends a certificate
indicating its identity.
When \fICURLOPT_SSL_VERIFYHOST\fP is 2, that certificate must indicate
that the server is the server to which you meant to connect, or the
connection fails.
Curl considers the server the intended one when the Common Name field
or a Subject Alternate Name field in the certificate matches the host
name in the URL to which you told Curl to connect.
When the value is 1, the certificate must contain a Common Name field,
but it doesn't matter what name it says. (This is not ordinarily a
useful setting).
When the value is 0, the connection succeeds regardless of the names in
the certificate.
The default, since 7.10, is 2.
The checking this option controls is of the identity that the server
\fIclaims\fP. The server could be lying. To control lying, see
\fICURLOPT_SSL_VERIFYPEER\fP.
.IP CURLOPT_SSL_CIPHER_LIST
Pass a char *, pointing to a zero terminated string holding the list of
ciphers to use for the SSL connection. The list must be syntactically correct,
@ -1040,6 +1095,7 @@ compile OpenSSL.
You'll find more details about cipher lists on this URL:
\fIhttp://www.openssl.org/docs/apps/ciphers.html\fP
.IP CURLOPT_KRB4LEVEL
Pass a char * as parameter. Set the krb4 security level, this also enables
krb4 awareness. This is a string, 'clear', 'safe', 'confidential' or