LFTP and the Stuck Login

I have been working on a new backup management system that utilizes the Synology and its ability to schedule tasks recently. Whilst I am untimely working on a program written in Go to be able to manage multiple backup configurations utilizing multiple backup protocols to achieve my goal I have been playing with the underlying software and protocols outside this program. One such piece of software is LFTP, this software allows for the transfer of files utilizing the FTP, FTPs, sFTP, HTTP, HTTPS and other protocols but the afore mentioned ones are the ones that are important for the software I am writing, but most importantly it supports mirroring with the FTP series protocols

Whilst I am writing this software I still wanted to get backups of the system running, to this end I was testing the LFTP commands and I hit an issue where the system will simply not connect to the server, yet the regular FTP client works fine.

Firstly we have to understand that LFTP does not connect to the server until the first command is issued, in the case of the example below, this was ls. Once this command is issued LFTP attempts to connect to and log in to the server, and this is where the issue happens, LFTP just hangs at “Logging In”

user@server backupfolder$ lftp -u username,password ftp.hostname.comlftp username@ftp.hostname.com:~> ls`ls' at 0 [Logging in...] 

To work out what the issues I had to do a little research and it comes down the fact the LFTP wants to default to secure connections, which in and of itself is not a bad thing, in fact it is a good thing but many FTP servers are yet to implement the sFTP/FTPs protocols and as such we end up with a hang at login. There is, however, two ways to fix this.

The first way to fix this is to turn off FTP for this connection only which is done through the modified connect command of

lftp -e "set ftp:ssl-allow=off;" -u username,password ftp.hostname.com

This is best if you are dealing with predominantly secure sites, however as I said most FTP servers are still utilising the older insecure FTP protocol at which point it may be more beneficial to change the LFTP configuration to default to insecure mode (and then enable it if needed for the secure connections, depends on which you have more of). To do this we need to edit the LFTP config file, to do this do the following

Utilising your favorite text editor (vi, nano or whatever it matters not) the config file is at /etc/lftp.conf

At some point in the file (I suggest at the end) put the following line

set ftp:ssl-allow false

Save your configuration and the defaulting to secure is turned off and your LFTP connection should work

Have Fun

Justin

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