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Diffstat (limited to 'docs/libcurl-the-guide')
| -rw-r--r-- | docs/libcurl-the-guide | 29 |
1 files changed, 29 insertions, 0 deletions
diff --git a/docs/libcurl-the-guide b/docs/libcurl-the-guide index 3892f5860..7ab8c31a9 100644 --- a/docs/libcurl-the-guide +++ b/docs/libcurl-the-guide @@ -869,6 +869,35 @@ Cookies Without Chocolate Chips getting lost. +FTP Peculiarities We Need + + FTP transfers use a second TCP/IP connection for the data transfer. This is + usually a fact you can forget and ignore but at times this fact will come + back to haunt you. libcurl offers several different ways to custom how the + second connection is being made. + + libcurl can either connect to the server a second time or tell the server to + connect back to it. The first option is the default and it is also what works + best for all the people behind firewals, NATs or ip-masquarading setups. + libcurl then tells the server to open up a new port and wait for a second + connection. This is by default attempted with EPSV first, and if that doesn't + work it tries PASV instead. (EPSV is an extension to the original FTP spec + and does not exist nor work on all FTP servers.) + + You can prevent libcurl from first trying the EPSV command by setting + CURLOPT_FTP_USE_EPSV to FALSE. + + In some cases, you will perfer to have the server connect back to you for the + second connection. This might be when the server is perhaps behind a firewall + or something and only allows connections on a single port. libcurl then + informs the remote server which IP address and port number to connect to. + This is made with the CURLOPT_FTPPORT option. If you set it to "-", libcurl + will use your system's "default IP address". If you want to use a particular + IP, you can set the full IP address, a host name to resolve to an IP address + or even a local network interface name that libcurl will get the IP address + from. + + Headers Equal Fun Some protocols provide "headers", meta-data separated from the normal |