How to transfer files between devices

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date: 2023-02-26 16:21:23

categories: default

firstPublishDate: 2022-04-22 23:01:45

I use multiple devices and I need to copy files between them. I mainly transfer the files with ssh/scp/sftp, rsync, samba/cifs, web and ftp servers.

SSH

In general, I setup an openssh server on my computers and I use scp/sftp to transfer files. I setup an ssh key on the machines to avoid entering my password each time I transfer a file. On my iphone, I use the FTPManager app which has sftp to transfer files (my photos and videos) to my computers.

Here are the commands for setting up ssh:

apt-get install openssh-server

# Generate an ssh key (in the client)
# sshKey is the secret key filename and sshKey.pub is the public key
ssh-keygen -t rsa -f sshKey -b 4096 -N 'passphrase' -C name@example.com

# Copy the public key to the server
scp sshKey.pub name@example.com:.ssh/authorized_keys

# To test the setup, connect to the server
ssh -i sshKey name@example.com

# Copy the secret key to ~/.ssh in the client
chmod 600 sshKey
mv sshKey ~/.ssh/

# Create the ssh config file:
vi ~/.ssh/config
# keep connection alive (for NAT routers)
Host *
    ServerAliveInterval 290
    ServerAliveCountMax 2
Host example.com
        HostName example.com
        User name
        IdentityFile ~/.ssh/sshKey
:wq

# In the client, add the key to ssh-agent to type the passphrase only once
eval `ssh-agent`
ssh-add ~/.ssh/sshKey

# To copy a file or a tree, run
scp file example.com:Downloads/
scp -r directory example.com:Downloads/

When I want to browse the file system and transfer files, I use midnight commander:

apt-get install mc
mc
# then F9 > Right > SFTP link > example.com

With SSH, it is possible to use a middle machine to transfer files:

Machine A has the files

Machine B is in the middle

Machine C downloads from machine A

For this, I use `tar`:

# From C
# the data is compressed with bzip2 on the network:
ssh B 'ssh A "/bin/tar cj file1 dir2 file3"' | tar xj

Sharing drives

I share drives through the local network with samba/cifs. I have my media on a server and the server disk is shared with my other machines.

Samba Wikipedia

I wrote about my samba setup in

how to share files with samba

In the past, I also used NFS. I stopped using it because the clients were crashing when there was a problem with the server.

NFS

Rsync

I use rsync because sometimes scp/sftp fail (large transfer and going offline,...) and with rsync it is possible to resume a transfer. Unison is command that synchronizes directory between machines, I haven't used it in along time..

# Copy a directory
rsync -az directory/ example.com:Dowloads/
# If the ssh key is not configured
rsync -az -e 'ssh -i ~/.ssh/sshKey' directory/ example.com:Dowloads/

# To resume a transfer
rsync -az --partial directory/ example.com:Dowloads/

# with unison
unison directory/ ssh://example.com/Downloads/

Web server

I usually setup the lighttpd web server, then copy files to the web root '/var/www/' and download the files with a web browser.

Setup:

apt-get install lighttpd
vi /etc/lighttpd/lighttpd.conf
server.document-root        = "/var/www"
at the end:
server.dir-listing = "enable"

/etc/init.d/lighttpd restart

FTP

I install pure-ftpd server, there is no configuration and it works directly after installation:

apt-get install pure-ftpd

The ftp clients I use are `ncftp` and `mc`:

apt-get install ncftp mc

# ncftp usage
# open connection
open -u user serverAddress
# copy directory from client machine to server
put -R directory

# mc usage
# To open connection: Choose FTP link...
ftp://user@serverAddress
# on older mc, it is:
user@serverAddress

Other alternatives

Syncthing is a background program that copies or deletes files in specified directories between computer.

Nextcloud uses the same principle but there is a server storing all the data. Nextcloud has apps for iOS and Android, so it is convenient for copying files to/from phones.

I don't use these systems because they take resources while not using them and I don't transfer files everyday.

Syncthing

Nextcloud

Sshfs allows sharing a drive on a remote machine through an ssh connection, it is similar to samba and it needs a mount point on the local machine.

Tags: #ssh #rsync #samba #cifs #ftp

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