[GLLUG] ftp

[Matt Graham]

On Monday 26 August 2002 15:07, after a long battle with technology, 
chuck williams wrote:
> is passive mode an option in command line ftp?
>
> I could find just "one" reference to it as PASV but that didn't help.
> Suppose I should keep on readin' n lookin' ...

It depends on the client.  Which one are you using?  The "standard" 
lukemftp client (in /usr/bin/ftp , usually) defaults to passive FTP and 
falls back to active FTP if passive doesn't work.  If you enter the 
command "passive", it defaults to active FTP and won't use passive.  
Enter "passive" again to switch.

ncftp does things in a similar way, you enter "passive on", "passive 
off", or "passive optional" (the default, ncftp will choose to use 
passive mode or not depending on what it thinks is best.)

PASV , as is suggested by its being in all-caps and only 4 letters long, 
is a primitive command passed to the remote system over a raw 
connection, much like HELO or USER or PASS or LIST.  The user of a 
frontend (like /usr/bin/ftp ) should not have to use these primitive 
commands.  These primitive commands can be useful sometimes though:

machine:~$ telnet mailhost.somewhere.org 110
Connected to mailhost.somewhere.org
Escape character is '^]'.
+OK FooMail POP3 server ready.
USER mhgraham
+OK please send PASS command
PASS example
+OK mhgraham is welcome here
LIST
+OK 0 messages
.
QUIT
+OK mhgraham FooMail POP3 server signing off.
Connection closed by foreign host.
machine:~$ 

...if you know these things, you can read your POP3 mail anywhere, 
regardless of whether there's a mail client installed, no configuration 
or installation of any other programs necessary, no track marks left on 
the machine you're using.  The 4-letter codes are typically specified 
in the relevant RFC.

-- 
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   --Matt Groening, "Love Is Hell"
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