curl: (35) OpenSSL SSL_connect: SSL_ERROR_SYSCALL in connection to domain.com:443

Question

I'm hitting my curl on ubuntu terminal and getting this response curl: (35) OpenSSL SSL_connect: SSL_ERROR_SYSCALL in connection to domain.com:443 . I really can't understand why it happens. I tried to show curl's error number but it did not revert any no. I am hitting another server. Below is my command :

./curl -i --tlsv1.2 -kv -H "Content-Type: application/xml" --verbose -X POST --data /var/www/html/xml.xml --cacert /root/curl_ssl/curl-7.54.1/src/cert_org.crt domain.com/otp

Please suggest some help.

Answer 1

For sites that use the old SSL protocol, this error may occur with CURL on Linux. According to the SSL/TLS protocol specification, the reason may be that the client hello uses the support group option that is not supported by the peer. The solution is to use sslscan for probing and get the protocol version and cipher suite supported by the peer. SSLscan (Github)