Re: unrecoverable ftp timeout

[Joerg Thuemmler <listen vordruckleitverlag de>]

Am 03.09.2018 um 11:34 schrieb wwp:
> Hello!
>
> there's something I'm experiencing quite frequently now, I'm not sure I
> was facing this behaviour w/ former versions: it's losing the FTP
> connection after a while being inactive then there is no way to free the
> VFs from the 'Active VFS directories' (it's listed in) and there is no
> way to re-instantiate the connection again.
>
> If I try from the 'Directory hotlist', I get a:
>    Cannot chdir to "/ftp://....";
>    Remote I/O error (121))
> if I try from 'FTP link...', I get only:
>    Cannot chdir to "/ftp://....";
>
> The only way I've found to reconnect to a lost FTP connection is
> restarting mc, which is not convenient nor expected.
>
> mc 4.8.1 compiled from the sources, on am up-to-date CentOS7 box:
> $ mc --version
> GNU Midnight Commander 4.8.21
> Built with GLib 2.54.2
> Using the S-Lang library with terminfo database
> With builtin Editor
> With subshell support as default
> With support for background operations
> With mouse support on xterm and Linux console
> With support for X11 events
> With internationalization support
> With multiple codepages support
> Virtual File Systems: cpiofs, tarfs, sfs, extfs, ftpfs, sftpfs, fish, smbfs
> Data types: char: 8; int: 32; long: 64; void *: 64; size_t: 64; off_t: 64;
>
>
> Regards,

Hi,

AFAIK it's an old thing mc is blocked after some ftp trouble. For 
instance, copying files on the server's side usually blocks. Opening FTP 
dir, pressing F5 on a file on the ftp side and giving a destination name 
without path (so it has to copy on the ftp server itself) always leads 
to an blocked mc (there is no "copy"-command in ftp).

Also I noted ftp servers, which do block the connection after some idle 
time and if you try to use this connection, they want you to reconnect 
and to put in your password once more. Mc caches your pw and resends it, 
but the new connection is started in the ftp users root dir (on the ftp 
server) again, not in the dir you last used. That may confuse the vfs 
system, but it's a problem connected with the ftp server's usual 
behavior (mc could resend the "cd" commands then after reconnection, 
dunno whether it's possible to cache last dir before timeout disconnect).

I'm usually connecting via "FTP link", which reconnects correctly but 
restarts in the users root. Classical "ftp" command cannot reconnect. 
And there is maybe a servers property possible, that forbids auto 
reconnection...

There may be another problem. dunno whether that's real, as I'm not a 
network pro. In http connections can use a session ID, after timeout 
disconnect and reconnect you always get a new one. If the same thing is 
possible and used in ftp, maybe in newer implementations, you will get a 
problem too.

I would try to get a later timeout on the used ftp server, as I believe 
it's an old "feature" and will not be changed next time, espacially as 
sftp will become a more important ftp replacing... Maybe you should 
change some other properties of your ftp servers making trouble if you 
try to re-connect. But this depends on ftp server program used.

regards

--
Joerg Thuemmler