mirror of
https://github.com/moparisthebest/curl
synced 2024-10-31 15:45:12 -04:00
fb23b85770
get a fresh one downloaded and created with 'make ca-bundle' or you can get one from here => http://curl.haxx.se/docs/caextract.html if you want a fresh new one extracted from Mozilla's recent list of ca certs. The configure option --with-ca-bundle now lets you specify what file to use as default ca bundle for your build. If not specified, the configure script will check a few known standard places for a global ca cert to use.
92 lines
4.2 KiB
Plaintext
92 lines
4.2 KiB
Plaintext
Peer SSL Certificate Verification
|
|
=================================
|
|
|
|
libcurl performs peer SSL certificate verification by default. This is done
|
|
by using CA cert bundle that the SSL library can use to make sure the peer's
|
|
server certificate is valid.
|
|
|
|
If you communicate with HTTPS or FTPS servers using certificates that are
|
|
signed by CAs present in the bundle, you can be sure that the remote server
|
|
really is the one it claims to be.
|
|
|
|
Until 7.18.0, curl bundled a severely outdated ca bundle file that was
|
|
installed by default. These days, the curl archives include no ca certs at
|
|
all. You need to get them elsewhere. See below for example.
|
|
|
|
If the remote server uses a self-signed certificate, if you don't install a CA
|
|
cert bundle, if the server uses a certificate signed by a CA that isn't
|
|
included in the bundle you use or if the remote host is an impostor
|
|
impersonating your favorite site, and you want to transfer files from this
|
|
server, do one of the following:
|
|
|
|
1. Tell libcurl to *not* verify the peer. With libcurl you disable this with
|
|
curl_easy_setopt(curl, CURLOPT_SSL_VERIFYPEER, FALSE);
|
|
|
|
With the curl command line tool, you disable this with -k/--insecure.
|
|
|
|
2. Get a CA certificate that can verify the remote server and use the proper
|
|
option to point out this CA cert for verification when connecting. For
|
|
libcurl hackers: curl_easy_setopt(curl, CURLOPT_CAPATH, capath);
|
|
|
|
With the curl command line tool: --cacert [file]
|
|
|
|
3. Add the CA cert for your server to the existing default CA cert bundle.
|
|
The default path of the CA bundle used can be changed by running configure
|
|
with the --with-ca-bundle option pointing out the path of your choice.
|
|
|
|
To do this, you need to get the CA cert for your server in PEM format and
|
|
then append that to your CA cert bundle.
|
|
|
|
If you use Internet Explorer, this is one way to get extract the CA cert
|
|
for a particular server:
|
|
|
|
o View the certificate by double-clicking the padlock
|
|
o Find out where the CA certificate is kept (Certificate>
|
|
Authority Information Access>URL)
|
|
o Get a copy of the crt file using curl
|
|
o Convert it from crt to PEM using the openssl tool:
|
|
openssl x509 -inform DES -in yourdownloaded.crt \
|
|
-out outcert.pem -text
|
|
o Append the 'outcert.pem' to the CA cert bundle or use it stand-alone
|
|
as described below.
|
|
|
|
If you use the 'openssl' tool, this is one way to get extract the CA cert
|
|
for a particular server:
|
|
|
|
o openssl s_client -connect xxxxx.com:443 |tee logfile
|
|
o type "QUIT", followed by the "ENTER" key
|
|
o The certificate will have "BEGIN CERTIFICATE" and "END CERTIFICATE"
|
|
markers.
|
|
o If you want to see the data in the certificate, you can do: "openssl
|
|
x509 -inform PEM -in certfile -text -out certdata" where certfile is
|
|
the cert you extracted from logfile. Look in certdata.
|
|
o If you want to trust the certificate, you can append it to your
|
|
cert_bundle or use it stand-alone as described. Just remember that the
|
|
security is no better than the way you obtained the certificate.
|
|
|
|
4. If you're using the curl command line tool, you can specify your own CA
|
|
cert path by setting the environment variable CURL_CA_BUNDLE to the path
|
|
of your choice.
|
|
|
|
If you're using the curl command line tool on Windows, curl will search
|
|
for a CA cert file named "curl-ca-bundle.crt" in these directories and in
|
|
this order:
|
|
1. application's directory
|
|
2. current working directory
|
|
3. Windows System directory (e.g. C:\windows\system32)
|
|
4. Windows Directory (e.g. C:\windows)
|
|
5. all directories along %PATH%
|
|
|
|
5. Get a better/different/newer CA cert bundle! One option is to extract the
|
|
one a recent Mozilla browser uses by running 'make ca-bundle' in the curl
|
|
build tree root, or possibly download a version that was generated this
|
|
way for you:
|
|
|
|
http://curl.haxx.se/docs/caextract.html
|
|
|
|
Neglecting to use one of the above methods when dealing with a server using a
|
|
certificate that isn't signed by one of the certificates in the installed CA
|
|
cert bundle, will cause SSL to report an error ("certificate verify failed")
|
|
during the handshake and SSL will then refuse further communication with that
|
|
server.
|