FTP: Difference between revisions

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FTP (or '''F'''ile '''T'''ransfer '''P'''rotocol) is a protocol that allows you to transfer files from a server to a client and vice versa (as FTP uses a client-server architecture). FTP is among the oldest protocols as its origins can be traced as far back as 1971 according to [https://en.wikipedia.org/wiki/Ftp#History_of_FTP_servers Wikipedia].
FTP (or '''F'''ile '''T'''ransfer '''P'''rotocol) is a protocol that allows you to transfer files from a server to a client and vice versa (as FTP uses a client-server architecture). FTP is among the oldest protocols as its origins can be traced as far back as 1971 according to [https://datatracker.ietf.org/doc/html/rfc114 RFC 114].


Variants of FTP also exist, including SFTP (SSH FTP, not to be confused with Simple FTP) and FTPS (FTP with SSL). SFTP, as the name implies, is done over SSH. FTPS is plain FTP with TLS/SSL encryption.
Variants of FTP also exist, including SFTP (SSH FTP, not to be confused with Simple FTP) and FTPS (FTP with TLS). SFTP, as the name implies, is done over SSH. FTPS is plain FTP with TLS encryption.


Alpine Linux has various FTP clients and servers that you can install and use, including the following:
Alpine Linux has various [[#Clients|FTP clients]] and [[#Servers|FTP servers]] that you can install and use.


* {{Pkg|vsftpd}} (server)
== Servers ==
* {{Pkg|ncftp}} (client)
=== vsftpd ===
* {{Pkg|lftpd}} (client)


Plenty of other clients also exist, but the ones mentioned above are the only ones covered. See [[#Clients]] for more details.
[https://security.appspot.com/vsftpd.html vsftpd] is secure, extremely fast and stable FTP server for UNIX-like systems.  It's also recommended because of relatively easy configuration.


= Servers =
Below is a list of features vsftpd has:
== vsftpd ==
 
In Alpine Linux the default FTP server is {{Pkg|vsftpd}}. However, it's not widely used due to common hosting panels not handling it's configuration management. In contrast, {{Pkg|vsftpd}} is more secure and doesn't require many updates.
 
vsftpd also claims it's the "most secure and fastest FTP server for UNIX-like systems".  It's the default FTP server in NimbleX, Slackware, and many other Linux distributions. In addition, it's also recommended because of relatively easy configuration.


{| class="wikitable"
{| class="wikitable"
|-
|-
! Feature                                !! Value/Name                      !! Observations
! Feature                                !! Value/Name                      !! Notes
|-
| Package name                            || vsftpd                          || <code><nowiki>apk add vsftpd</nowiki></code>
|-
| Manpages and <code>-doc</code> packages || vsftpd-doc                      || <code><nowiki>apk add vsftpd-doc</nowiki></code>
|-
|-
| Configuration file                      || {{Path|/etc/vsftpd/vsftpd.conf}} || The default config is stock from vsftpd
| Configuration file                      || {{Path|/etc/vsftpd/vsftpd.conf}} || The default config is stock from vsftpd
Line 32: Line 22:
| Log Files                              || {{Path|/var/log/vsftpd.log}}    || Configurable in vsftp.conf
| Log Files                              || {{Path|/var/log/vsftpd.log}}    || Configurable in vsftp.conf
|-
|-
| User Running The Service                || vsftpd                          || Alpine does '''not''' have an "ftp" user; it uses a group with the same name instead.
| User Running The Service                || vsftpd                          || Alpine does '''not''' have an {{ic|ftp}} user; it uses a group with the same name instead.
|-
|-
| Group(s) to common to                  || vsftpd                          || Used to share things among others daemons or services, like Redis or Apache
| Group(s) to common to                  || vsftpd                          || Used to share things among others daemons or services, like Redis or Apache
|}
|}


==== Limitations ====
==== Installation ====


* SFTP is not supported
To Install the {{Pkg|vsftpd|arch=}} package:{{Cmd|# apk add vsftpd}} Optionally install the {{Pkg|vsftpd-doc|arch=}} package alongside for documentation.


=== Installing vsftpd ===
==== Configuration ====


To install and run vsftpd, simply run:
The default configuration is not ideal because anonymous access is enabled by default and only IPv4 support is enabled. Therefore, the default configuration should not be used in a production environment. Some common server configuration schemes include allowing anonymous access of files, user system FTP services, and virtual users (on the server end).


<pre>
Per-user FTP files can be supported by special directive in the {{Path|/etc/vsftpd/vsftpd.conf}} file using {{ic|user_sub_token}}. For example, this can be set to something like {{Path|/home/$USER/public_ftp}}.
apk add vsftpd


rc-update add vsftpd default
The {{ic|vsftpd service}} can be enabled and the usual start|stop|restart|reload options are available as per [[OpenRC]] page: {{Cmd|<nowiki># rc-update add vsftpd default
# rc-service vsftpd start</nowiki>}}


rc-service vsftpd restart
After changing the configuration file, you must either restart or reload vsftpd service in order for the new configuration to take effect.
</pre>


=== Configuring vsftpd ===
To test your FTP server configuration, refer to [[#Troubleshooting|Troubleshooting]] section.


The default configuration is not ideal because anonymous access is enabled by default and IPv4 support is only enabled. Therefore, the default configuration should not be considered suitable for production uses. Some common server configuration schemes include allowing anonymous access of files, user system FTP services, and virtual users (on the server end).
== Clients ==


Per user FTP files can be supported by special directive in the vsftp.conf file using <code>user_sub_token</code>. For example, this can be set to something like {{Path|/home/$USER/public_ftp}} if we enable it (process are described below in further section "vsftpd configuration"
Because FTP uses a client-server architecture, you will need an FTP client if you want to interact with an FTP server. Alpine Linux provides several packages for command-line FTP clients. A few are listed here:


=== Managing vsftpd ===
{| class="wikitable"
|-
! FTP Client
|-
|[[#lftp|lftp]]
|-
|{{Pkg|ncftp}}
|-
|[[#PCManFM|PCManFM]]
|}


'''Starting vsftpd''': After the installation {{Pkg|vsftpd}} is not running. As we said in first section, was started already but if you want to start {{Pkg|vsftpd}} manually use:
=== lftp ===


{{Cmd|rc-service vsftpd start}}
[https://lftp.yar.ru/ lftp] is a sophisticated file transfer program that supports a number of network protocols, including FTP, HTTP, SFTP, FISH, and BitTorrent.  
 
If starting vsftpd went OK, you should see output similar to the following:
 
<pre>
* Caching service dependencies ...                          [ ok ]
* Starting vsftpd...                                        [ ok ]
</pre>
 
'''Stopping vsftpd''': if you want to stop the web server use ''stop'' in the same way of previous command:
 
{{Cmd|rc-service vsftpd stop}}
 
'''Restarting or reloading vsftpd''': After changing the configuration file, you must either restart or reload vsftpd in order for the new configuration to take effect. You can run one of the following commands below to achieve the desired effect:
 
{{Cmd|rc-service vsftpd restart}}
{{Cmd|rc-service vsftpd reload}}
 
The latter reloads vsftpd's configuration file while the former restarts vsftpd entirely. The latter might be preferred as it prevents having to reload vsftpd entirely.
 
If you ''restarted'' vsftpd, there should be output similar to the following:
<pre>
* Stopping vsftpd...                                        [ ok ]
* Starting vsftpd...                                        [ ok ]
</pre>
 
If you ''reloaded'' vsftpd, the output will be similar to the following instead:
 
<pre>
* Reloading vsftpd...                                        [ ok ]
</pre>
 
'''Using the proper runlevel''': using the "default" runlevel should work in most cases, although there might be custom runlevels present and it might be more desirable to add vsftpd to a runlevel other than "default". However, keep in mind that runlevels aren't present in Docker containers because Alpine is used mostly in Docker.
 
To add vsftpd to a runlevel, use the following command:
 
{{Cmd|rc-update add vsftpd [runlevel]}}
 
Where <code>[runlevel]</code> is the name of the runlevel you want to add the vsftpd service too. For example, if you want to add vsftpd to the "default" run level, run <code>rc-update add vsftpd default</code>
 
 
=== Testing vsftpd ===
 
This section is assuming that vsftpd is running. At the moment, there might not be the 'ftp' user allowed or even available, but the server is up and running.
 
You can use netcat to test if a connection to the server is successful:
 
{{Cmd|nc -zv server_address}}
 
Be sure to change <code>server_address</code> with the actual IP address of the server. The common response will be '''OPEN''' if the server is running. If you receive another response, review your server configuration.
 
= Clients =
 
Because FTP uses a client-server architecture, you will need an FTP client if you want to interact with an FTP server. Alpine provides several packages for command-line FTP clients:
 
* {{Pkg|lftp}}. Check out [[#lftp]]
* {{Pkg|ncftp}}
 
If you prefer a graphical client, check out the following:
 
* {{Pkg|pcmanfm}}. See PCManFM with GVfs]]
 
Some web browsers also support FTP, although most major such as Chrome and Firefox removed support.
 
== lftp ==
 
lftp is a sophisticated file transfer program that supports a number of network protocols, including FTP, HTTP, SFTP, FISH, and BitTorrent. It also has the following features:
 
* Job control
* Support for bookmarks
* Support for a built-in mirror command
* Support for parallel file transfers
* <code>readline</code> used for input


{| class="wikitable"
{| class="wikitable"
Line 141: Line 67:
! Feature                                !! Value/Name !! Notes
! Feature                                !! Value/Name !! Notes
|-
|-
| Package Name                            || lftp                                    || Install: <code><nowiki>apk add lftp</nowiki></code>
| Package Name                            || lftp                                    || Install: {{ic|apk add lftp}}
|-
|-
| Manpages and <code>-doc</code> Packages || vsftpd-doc                              || Install: <code><nowiki>apk add lftp-doc</nowiki></code>
| Manpages and <code>-doc</code> Packages || vsftpd-doc                              || Install: {{ic|apk add {{pkg|lftp-doc|arch=}}}}
|-
|-
| System Configuration Files              || {{Path|/etc/lftp.conf}}                || Little to no customizations are made by Alpine
| System Configuration Files              || {{Path|/etc/lftp.conf}}                || Little to no customizations are made by Alpine
Line 150: Line 76:
|}
|}


=== Installing lftp ===
==== Installation ====


To install lftp, run <pre>apk add lftp</pre>
To install lftp, run {{Cmd|apk add lftp}}


lftp has been provided in the main repository since Alpine 3.6, so it's a supported package that's ready for production use.
==== Configuration ====


=== Configuring lftp ===
The main configuration file, {{path|/etc/lftp.conf}}, comes with different examples and comments. On startup, lftp reads {{path|/etc/lftp.conf}}, {{path|~/.lftprc}}, and {{path|~/.lftp/rc}} in that exact order. These files are used to set system-wide and user-specific settings.
 
The main configuration file, <code><nowiki>/etc/lftp.conf</nowiki></code> comes with different examples and comments. On startup, lftp reads <code>/etc/lftp.conf</code>, <code>~/.lftprc</code>, and <code>~/.lftp/rc</code> in that exact order. These files are used to set system-wide and user-specific settings.


In the configuration file, use the command set followed by the name of the setting followed by its value. Use <code>on</code>/<code>off</code> for boolean values. For example:
In the configuration file, use the command set followed by the name of the setting followed by its value. Use <code>on</code>/<code>off</code> for boolean values. For example:
Line 172: Line 96:


<pre>
<pre>
<nowiki>
set ftp:use-feat off /example.com
set ftp:use-feat off /example.com
set ftp:ssl-force on /example.com
set ftp:ssl-force on /example.com
</nowiki>
</pre>
</pre>


{{Note|The closure for `dns:', `net:', `ftp:', `http:', `hftp:' domain variables is currently just the host name as you specify it in the `open' command (with some exceptions where closure is meaningless, e.g., dns:cache-size). For some `cmd:' domain variables the closure is the current URL without path. For other variables, it is currently not used. See examples in the sample lftp.conf.}}
{{Note|The closure for {{ic|dns:}}, {{ic|net:}}, {{ic|ftp:}}, {{ic|http:}}, and {{ic|hftp:}} domain variables is currently just the host name as you specify it in the {{ic|open}} command (with some exceptions where closure is meaningless, e.g., {{ic|dns:cache-size}}). For some {{ic|cmd:}} domain variables the closure is the current URL without path. For other variables, it is currently not used. See examples in the sample {{ic|lftp.conf}}.}}


=== More on lftp ===
==== lftp usage ====
 
Below is an example of a mult-part download over SFTP:{{Cmd|$ lftp -e 'pget -c -n 5 /path/to/file' <nowiki>sftp://username@server</nowiki>}}
 
Breakdown:
* -e: execute a command
* pget: the command for partial download, in addition to its options:
** -c: option to resume
** -n: option for number of parts
* <nowiki>sftp://username@server</nowiki>: server URL


By default, lftp is not very verbose about operations it performs in the background. If you want more output, you can use the 'debug' command (without the 'set' command):
By default, lftp is not very verbose about operations it performs in the background. If you want more output, you can use the 'debug' command (without the 'set' command):
Line 189: Line 120:
Note that using the -d switch from the command line will override any previous debug settings and the full debug output will be displayed.
Note that using the -d switch from the command line will override any previous debug settings and the full debug output will be displayed.


If you prefer some commands to be called by another name, you can set aliases:
If you prefer some commands to be called by another name, you can set aliases using the <code>alias</code> command. The syntax is as follows:


lftpd supports aliases in the format <code>alias [name] [command]</code>, where <code>[name]</code> is the name of the lftpd alias and <code>[command]</code> is the name of the lftpd command. A couple of examples are shown below:
<pre>
alias [name] [command]
</pre>
 
<code>[name]</code> is the name of the lftpd alias and <code>[command]</code> is the name of the lftpd command. A couple of examples are shown below:


<pre>
<pre>
Line 204: Line 139:
The last alias should all be in one line. It gets a remote file, opens it with vim, and places the modified file back on the server. This can be very convenient when a file needs to be quickly edited and updated on the remote server.
The last alias should all be in one line. It gets a remote file, opens it with vim, and places the modified file back on the server. This can be very convenient when a file needs to be quickly edited and updated on the remote server.


=== Example usage ===
=== PCManFM ===
 
Below is an example of a mult-part download over SFTP:
 
<code>$ lftp -e 'pget -c -n 5 /path/to/file' <nowiki>sftp://username@server</nowiki></code>
 
Breakdown:
 
* -e: execute a command
* pget: the command for partial download, in addition to its options:
** -c: option to resume
** -n: option for number of parts
* <nowiki>sftp://username@server</nowiki>: server URL


== PCManFM with GVfs ==
[https://en.wikipedia.org/wiki/PCMan_File_Manager PCManFM] file manager available as {{pkg|pcmanfm}} package with the {{Pkg|gvfs}} plugin can be used as a graphical FTP client. To connect to an FTP server, you can do the following:
 
While PCManFM is a file manager, installing the {{Pkg|gvfs}} plugin allows you to use it as a graphical FTP client. To connect to an FTP server, you can do the following:


# From the menubar, go to Go > Connect to a server
# From the menubar, go to Go > Connect to a server
Line 228: Line 149:
[[File:Ftp-gui-pcmanfm_at_2020-09-11_14-13-03.png]]
[[File:Ftp-gui-pcmanfm_at_2020-09-11_14-13-03.png]]


= See Also =
== Troubleshooting ==
 
For testing, there might not be the {{ic|ftp}} user allowed or even available, but [[#vsftpd|vsftpd]] or some other ftp server server must be up and running.  Use {{ic|netcat}} command from the {{pkg|netcat|arch=}} package to test if a connection to the server is successful: {{Cmd|nc -zv [server_address]}}
 
Be sure to change {{ic|[server_address]}} with the actual IP address of the server. The common response will be '''OPEN''' if the server is running. If you receive another response, review your server configuration.
 
== See Also ==


* [[PXE boot]]
* [[PXE boot]]
* [[Alpine newbie]]
* [https://security.appspot.com/vsftpd.html vsftpd Homepage]
* [[Alpine newbie developer]]
* [https://lftp.yar.ru/ lftp Homepage]


[[Category:Newbie]]
[[Category:Server]]
[[Category:Web_Server]]
[[Category:Web_Server]]
[[Category:Development]]

Latest revision as of 17:28, 15 April 2025

FTP (or File Transfer Protocol) is a protocol that allows you to transfer files from a server to a client and vice versa (as FTP uses a client-server architecture). FTP is among the oldest protocols as its origins can be traced as far back as 1971 according to RFC 114.

Variants of FTP also exist, including SFTP (SSH FTP, not to be confused with Simple FTP) and FTPS (FTP with TLS). SFTP, as the name implies, is done over SSH. FTPS is plain FTP with TLS encryption.

Alpine Linux has various FTP clients and FTP servers that you can install and use.

Servers

vsftpd

vsftpd is secure, extremely fast and stable FTP server for UNIX-like systems. It's also recommended because of relatively easy configuration.

Below is a list of features vsftpd has:

Feature Value/Name Notes
Configuration file /etc/vsftpd/vsftpd.conf The default config is stock from vsftpd
Default Path For Files /var/lib/ftp Because anonymous access is enabled by default, this is the daemon's default home directory
Log Files /var/log/vsftpd.log Configurable in vsftp.conf
User Running The Service vsftpd Alpine does not have an ftp user; it uses a group with the same name instead.
Group(s) to common to vsftpd Used to share things among others daemons or services, like Redis or Apache

Installation

To Install the vsftpd package:

# apk add vsftpd

Optionally install the vsftpd-doc package alongside for documentation.

Configuration

The default configuration is not ideal because anonymous access is enabled by default and only IPv4 support is enabled. Therefore, the default configuration should not be used in a production environment. Some common server configuration schemes include allowing anonymous access of files, user system FTP services, and virtual users (on the server end).

Per-user FTP files can be supported by special directive in the /etc/vsftpd/vsftpd.conf file using user_sub_token. For example, this can be set to something like /home/$USER/public_ftp.

The vsftpd service can be enabled and the usual start|stop|restart|reload options are available as per OpenRC page:

# rc-update add vsftpd default # rc-service vsftpd start

After changing the configuration file, you must either restart or reload vsftpd service in order for the new configuration to take effect.

To test your FTP server configuration, refer to Troubleshooting section.

Clients

Because FTP uses a client-server architecture, you will need an FTP client if you want to interact with an FTP server. Alpine Linux provides several packages for command-line FTP clients. A few are listed here:

FTP Client
lftp
ncftp
PCManFM

lftp

lftp is a sophisticated file transfer program that supports a number of network protocols, including FTP, HTTP, SFTP, FISH, and BitTorrent.

Feature Value/Name Notes
Package Name lftp Install: apk add lftp
Manpages and -doc Packages vsftpd-doc Install: apk add lftp-doc
System Configuration Files /etc/lftp.conf Little to no customizations are made by Alpine
User Configuration Files ~/.lftprc, ~/.lftp/rc The former is read first while the latter is read second if the former was not found.

Installation

To install lftp, run

apk add lftp

Configuration

The main configuration file, /etc/lftp.conf, comes with different examples and comments. On startup, lftp reads /etc/lftp.conf, ~/.lftprc, and ~/.lftp/rc in that exact order. These files are used to set system-wide and user-specific settings.

In the configuration file, use the command set followed by the name of the setting followed by its value. Use on/off for boolean values. For example: 

set ftp:ssl-force on
set ssl:verify-certificate on
set ftp:use-feat off
set ftp:ssl-protect-data on

Specific settings can be set for specific servers only. Append a slash (/) in front of the server name for a specific server. 

set ftp:use-feat off /example.com
set ftp:ssl-force on /example.com
Note: The closure for dns:, net:, ftp:, http:, and hftp: domain variables is currently just the host name as you specify it in the open command (with some exceptions where closure is meaningless, e.g., dns:cache-size). For some cmd: domain variables the closure is the current URL without path. For other variables, it is currently not used. See examples in the sample lftp.conf.

lftp usage

Below is an example of a mult-part download over SFTP:

$ lftp -e 'pget -c -n 5 /path/to/file' sftp://username@server

Breakdown:

  • -e: execute a command
  • pget: the command for partial download, in addition to its options:
    • -c: option to resume
    • -n: option for number of parts
  • sftp://username@server: server URL

By default, lftp is not very verbose about operations it performs in the background. If you want more output, you can use the 'debug' command (without the 'set' command):

  • debug 5 will display the full debug output.
  • debug 3 will only display greeting messages and error messages.

Note that using the -d switch from the command line will override any previous debug settings and the full debug output will be displayed.

If you prefer some commands to be called by another name, you can set aliases using the alias command. The syntax is as follows: 

alias [name] [command]

[name] is the name of the lftpd alias and [command] is the name of the lftpd command. A couple of examples are shown below: 

alias dir ls
alias less more
alias zless zmore
alias bzless bzmore
alias reconnect "close; cache flush; cd ."
alias edit "eval -f "get $0 -o ~/.lftp/edit.tmp.$$ && shell \\"cp -p ~/.lftp/edit.tmp.$$ ~/.lftp/edit.tmp.$$.orig && vim ~/.lftp/edit.tmp.$$ && test ~/.lftp/edit.tmp.$$ -nt ~/.lftp/edit.tmp.$$.orig\\" && put ~/.lftp/edit.tmp.$$ -o $0; shell rm -f ~/.lftp/edit.tmp.$$*"

The last alias should all be in one line. It gets a remote file, opens it with vim, and places the modified file back on the server. This can be very convenient when a file needs to be quickly edited and updated on the remote server.

PCManFM

PCManFM file manager available as pcmanfm package with the gvfs plugin can be used as a graphical FTP client. To connect to an FTP server, you can do the following:

  1. From the menubar, go to Go > Connect to a server
  2. Choose the FTP protocol and input your username (path is optional)
  3. After a while you will input the password for the username you input

Troubleshooting

For testing, there might not be the ftp user allowed or even available, but vsftpd or some other ftp server server must be up and running. Use netcat command from the netcat package to test if a connection to the server is successful:

nc -zv [server_address]

Be sure to change [server_address] with the actual IP address of the server. The common response will be OPEN if the server is running. If you receive another response, review your server configuration.

See Also

Retrieved from "https://wiki.alpinelinux.org/w/index.php?title=FTP&oldid=29687"