--- c: Copyright (C) Daniel Stenberg, , et al. SPDX-License-Identifier: curl Long: ssl-reqd Help: Require SSL/TLS Protocols: FTP IMAP POP3 SMTP LDAP Added: 7.20.0 Category: tls imap pop3 smtp ldap Multi: boolean See-also: - ssl - insecure Example: - --ssl-reqd ftp://example.com --- # `--ssl-reqd` Require SSL/TLS for the connection - often referred to as STARTTLS or STLS because of the involved commands. Terminates the connection if the transfer cannot be upgraded to use SSL/TLS. This option is handled in LDAP (added in 7.81.0). It is fully supported by the OpenLDAP backend and rejected by the generic ldap backend if explicit TLS is required. This option is unnecessary if you use a URL scheme that in itself implies immediate and implicit use of TLS, like for FTPS, IMAPS, POP3S, SMTPS and LDAPS. Such a transfer always fails if the TLS handshake does not work. This option was formerly known as --ftp-ssl-reqd.