--connect-timeout选项。
繁殖：
time curl --connect-timeout 60 ftp://ftp.ossp.org/pkg/lib/uuid/uuid-1.6.2.tar.gz
无法弄清楚原因......
$ curl --version
curl 7.30.0 (x86_64-apple-darwin13.0) libcurl/7.30.0 SecureTransport zlib/1.2.5
Protocols: dict file ftp ftps gopher http https imap imaps ldap ldaps pop3 pop3s rtsp smtp smtps telnet tftp
Features: AsynchDNS GSS-Negotiate IPv6 Largefile NTLM NTLM_WB SSL libz