How to Install an SFTP Client App on Ubuntu 16.04 or 18.04 LTS

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To install an SFTP client app on Ubuntu 16.04 or 18.04 LTS, install OpenSSH’s client package with sudo apt update followed by sudo apt install openssh-client. The package provides the command-line sftp program. For a graphical client, install FileZilla and select SFTP rather than FTP.

Ubuntu 16.04 and 18.04 are legacy releases, so upgrade to a maintained Ubuntu LTS version whenever possible. The commands below are useful for administrators who must temporarily maintain an older Xenial or Bionic system, but old package repositories, authentication methods, host-key algorithms, and application builds may cause compatibility problems.

Key takeaways

• openssh-client provides Ubuntu’s command-line sftp, ssh, and scp programs.
• Ubuntu 16.04 ended standard security maintenance in April 2021, while Ubuntu 18.04 ended standard security maintenance in May 2023.
• SFTP normally uses SSH TCP port 22, but the remote administrator can configure a different port.
• Installing an SFTP client lets Ubuntu connect to a remote server; it does not create an SFTP server or grant access to a remote account.
• FileZilla provides a graphical alternative, but its connection must use SFTP – SSH File Transfer Protocol, not ordinary FTP.

How to install an SFTP client app on Ubuntu 16.04 or 18.04 LTS

The recommended primary method is to install the OpenSSH client from Ubuntu’s package repositories:

sudo apt update
sudo apt install openssh-client

Ubuntu’s OpenSSH documentation gives openssh-client as the package for OpenSSH client applications. The Bionic package information identifies the package that supplies the SFTP client, and the Ubuntu Bionic SFTP manual documents the command syntax.

The package is normally already installed on many Ubuntu desktop and server installations because other SSH tools depend on it. Installing it again is harmless and ensures that the sftp command is available.

Is Ubuntu 16.04 or 18.04 still supported?

Ubuntu 16.04 and Ubuntu 18.04 are past standard support and should not normally be used for a new installation. Canonical records standard security maintenance for Ubuntu 16.04 as ending in April 2021 and standard security maintenance for Ubuntu 18.04 as ending in May 2023. Canonical’s ESM information and release tables provide the lifecycle details.

Canonical lists Ubuntu 16.04 ESM coverage through April 2026 and Ubuntu 18.04 ESM coverage through April 2028, subject to Ubuntu Pro eligibility, architecture, subscription, and applicable terms. As of August 16, 2026, Ubuntu 16.04’s listed ESM period has passed, while Ubuntu 18.04 may still have ESM coverage under the relevant terms. Extended maintenance is not a substitute for planning an upgrade.

Before installing software, check the version:

lsb_release -a

If lsb_release is unavailable, use:

cat /etc/os-release

Upgrade the operating system whenever the machine’s application, hardware, and maintenance requirements permit. Use Canonical’s release-upgrade guidance rather than mixing repositories from a newer Ubuntu release into Xenial or Bionic.

Which SFTP client should you choose?

Choose OpenSSH for a terminal, server, script, or low-overhead workflow. Choose FileZilla when you need drag-and-drop transfers and a visual directory browser. Ubuntu’s file-manager integration can be convenient for occasional transfers, but its availability and menu labels depend on the desktop environment and installed components.

Need	Best choice	Why	Limitation
Minimal server or terminal workflow	OpenSSH sftp	Small, already designed for SSH systems, and available for scripts and automation	Requires terminal commands
Drag-and-drop file transfers	FileZilla	Graphical local and remote directory panes, transfer queue, and saved site profiles	Requires a graphical desktop and careful protocol selection
Occasional desktop access	File-manager SFTP integration	Can open an sftp:// location without a separate transfer window	Exact support and labels vary by desktop and installed packages
Repeated directory synchronization	rsync over SSH	Efficiently transfers changed files	Not a beginner-focused graphical client and requires suitable remote command support

What is the difference between an SFTP client and an SFTP server?

An SFTP client connects outward from Ubuntu to a remote SSH/SFTP service. An SFTP server accepts inbound connections from other computers. The package openssh-client installs the client; installing openssh-server is a separate action that exposes an SSH service and changes the machine’s inbound security posture.

If the goal is to download from or upload to another computer, do not install openssh-server unnecessarily. Installing a client also does not create a remote account, configure a server, or grant permission to a directory.

SFTP is not traditional FTP. SFTP operates through SSH and normally uses encrypted SSH transport, while FTP and FTPS are different protocols. Security still depends on correct host-key verification, authentication, server configuration, and the security of both endpoints. The Ubuntu SFTP manual documents SFTP as operating over an SSH transport.

What do you need before connecting to an SFTP server?

You need a reachable server hostname or IP address, a valid remote username, the SSH/SFTP port, an account password or private key, and permission to read or write the target remote directory. A VPN, firewall rule, bastion host, or security-group rule may also be required.

Installing an SFTP client does not provide any of those credentials or permissions. Obtain the connection details from the server administrator.

Test basic reachability if appropriate:

ping -c 4 server.example.com

A failed ping does not prove that SFTP is unavailable because many networks block ICMP. A TCP test against the SSH port is more useful:

nc -vz server.example.com 22

If Netcat is not installed:

sudo apt install netcat-openbsd

How do you verify and install OpenSSH SFTP?

1. Refresh package metadata

Run:

sudo apt update

A successful command downloads package lists without repository errors. Do not skip this step on an old installation: stale metadata can cause a package-not-found error or an incomplete dependency calculation.

2. Install the package

sudo apt install openssh-client

Confirm that the package is available before or after installation with:

apt-cache policy openssh-client

Check the command path:

command -v sftp

A typical result is:

/usr/bin/sftp

You can also verify the installed package:

dpkg -s openssh-client

Depending on the OpenSSH version, sftp -V may print a version or display usage information. The package query and command-path checks are more portable:

sftp -V

How do you connect with the Ubuntu SFTP command?

For a server using the normal SSH port, run:

sftp username@server.example.com

SFTP normally uses TCP port 22, but the server administrator may specify another port. Use capital -P for a non-standard port:

sftp -P 2222 username@server.example.com

Use -i to select a private key:

sftp -i ~/.ssh/id_ed25519 username@server.example.com

An older key file may use a different name, such as:

sftp -i ~/.ssh/id_rsa username@server.example.com

The capital -P is important. Lowercase -p has a different purpose in OpenSSH tools and is not the option for selecting a port.

You can request a starting directory on the remote server:

sftp username@server.example.com:/var/www

With a custom port:

sftp -P 2222 username@server.example.com:/backups

The remote path depends on the account’s permissions and filesystem view. A chrooted SFTP account may see its restricted directory as / rather than seeing the server’s actual filesystem root.

How should you handle the first host-key prompt?

On the first connection, OpenSSH may show the remote server’s host-key fingerprint and ask whether to continue. Verify the fingerprint through a trusted channel with the server administrator before accepting it. Do not automatically answer “yes” to every host-key prompt.

After acceptance, OpenSSH stores the host key in:

~/.ssh/known_hosts

The host key helps detect a changed or intercepted connection. A changed key can be legitimate after a server rebuild, but it can also indicate a security problem. Treat an unexpected fingerprint change as something to investigate, not as a routine warning to bypass.

Which SFTP commands transfer and manage files?

After connecting, the SFTP client displays an interactive prompt. The most useful commands distinguish between the remote directory and the local directory:

Command	Action
pwd	Show the current remote directory
lpwd	Show the current local directory
ls	List remote files
lls	List local files
cd directory	Change the remote directory
lcd directory	Change the local directory
get file.txt	Download a remote file
put file.txt	Upload a local file
get -r folder	Download a remote directory recursively
put -r folder	Upload a local directory recursively
mkdir folder	Create a remote directory
rm file.txt	Delete a remote file
bye	Disconnect from the server

The Bionic SFTP manual documents these interactive commands and the connection forms. Check the remote path with pwd and the local path with lpwd before uploading or downloading, especially when similarly named directories exist on both systems.

How do you install FileZilla on Ubuntu 16.04 or 18.04?

FileZilla is the main graphical alternative for users who want local and remote directory panes, drag-and-drop transfers, a transfer queue, and saved site profiles.

sudo apt update
sudo apt install filezilla

Launch FileZilla from the application menu by searching for FileZilla, or start it from a terminal:

filezilla

FileZilla’s Ubuntu manual identifies support for FTP, FTPS, and SFTP. Because the protocols are different, configure the connection as follows:

FileZilla field	Value
Protocol	SFTP – SSH File Transfer Protocol
Host	The server hostname or IP address
Port	22, unless the administrator supplied another port
Logon type	An available password, normal, key-file, or interactive authentication option
User	The remote SFTP username
Password	The remote password, if password authentication is used

FileZilla labels and authentication choices can vary by build, and Ubuntu 16.04 and 18.04 repositories may contain old FileZilla versions. In the Site Manager, confirm the protocol before saving the site. The left pane represents the local filesystem, the right pane represents the remote filesystem, and the transfer queue shows completed and failed transfers.

Do not put passwords or private keys in screenshots. Do not disable host-key or encryption warnings simply to force a connection, and do not store private keys in world-readable locations.

Can Ubuntu’s file manager connect to SFTP?

Some Ubuntu desktop environments and file managers can open an SFTP location using a URI such as:

sftp://username@server.example.com

This can be convenient for an occasional graphical transfer. Exact menu names and availability depend on the Ubuntu desktop edition, GNOME/Nautilus version, and installed GVfs components, so no single file-manager path is guaranteed on both Ubuntu 16.04 and 18.04. Use OpenSSH or FileZilla when you need a predictable, documented workflow.

How do you troubleshoot SFTP installation problems on old Ubuntu?

sftp: command not found

The OpenSSH client may be missing or incomplete. Run:

sudo apt update
sudo apt install --reinstall openssh-client
command -v sftp
dpkg -L openssh-client | grep '/sftp$'

E: Unable to locate package openssh-client

This usually indicates missing package metadata, broken APT sources, no network access, an incorrect release codename, or repositories that no longer serve the old release. Check the output of sudo apt update first. Do not add an unrelated modern Ubuntu repository to Xenial or Bionic.

404 Not Found or “does not have a Release file”

End-of-life Ubuntu installations commonly encounter repository errors after the normal mirrors stop publishing that release. Back up the repository configuration before making changes:

sudo cp /etc/apt/sources.list /etc/apt/sources.list.bak

If the system must temporarily remain on the old release, consult Ubuntu’s EOL repository guidance for the currently applicable archive instructions, then run:

sudo apt update

Prefer upgrading the operating system. Do not use apt-get --allow-unauthenticated, disable APT signature verification, or download random .deb files to work around repository errors. APT’s release signatures protect the integrity and origin of package metadata.

Broken dependencies

Old package states, interrupted upgrades, and mixed repositories can leave dependencies inconsistent. Read the complete APT error, inspect configured sources, and repair the release-management problem before installing packages from unrelated repositories. A clean upgrade or supported reinstall is safer than forcing incompatible packages.

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How do you troubleshoot SFTP connection errors?

Connection refused

A refused connection usually means the remote host is reachable but no service is accepting connections on the selected port, or a firewall is actively rejecting the connection. Check the hostname, port, remote SSH/SFTP service, firewall rules, security groups, and any required VPN or bastion host.

Connection timed out

A timeout commonly indicates routing, firewall, VPN, hostname, or IP-address problems rather than a missing local SFTP package. Test the actual SSH port with nc -vz and confirm the connection requirements with the administrator.

Permission denied

“Permission denied” can mean an incorrect username or password, an invalid private key, an account not authorized for SFTP, a non-writable remote directory, a restricted account path, or a server requiring keyboard-interactive or multifactor authentication.

Private keys commonly need restrictive local permissions:

chmod 600 ~/.ssh/id_ed25519

Changing local key permissions does not fix every permission error. Confirm which authentication method the server expects and whether the target remote directory allows the requested operation.

Host key verification failed

If the server was legitimately rebuilt or its host key changed, remove only the confirmed stale entry:

ssh-keygen -R server.example.com

Reconnect only after verifying the new fingerprint through a trusted channel. Do not delete the entire ~/.ssh/known_hosts file as the default fix.

subsystem request failed on channel 0

The remote SSH server may lack a configured SFTP subsystem, or the account may be restricted in a way that prevents SFTP. This is a server-side configuration problem; reinstalling the Ubuntu client generally will not fix it.

How can you get more diagnostic information?

Use verbose SSH diagnostics:

sftp -vvv username@server.example.com

Verbose output can reveal DNS failures, refused connections, authentication negotiation, host-key problems, unsupported algorithms, and subsystem errors. Remove usernames, hostnames, IP addresses, sensitive paths, and other private information before sharing a log publicly.

Old Ubuntu clients and modern servers may also disagree about supported cryptographic algorithms. Upgrade the client operating system or server before considering narrowly scoped compatibility settings. Forcing deprecated algorithms can weaken security and should not be a blanket or permanent fix.

What are the alternatives to an interactive SFTP client?

Using scp for a one-off copy

Use scp when you already know the exact source and destination:

scp file.txt username@server.example.com:/remote/path/

To download a file into the current local directory:

scp username@server.example.com:/remote/path/file.txt .

SFTP is more suitable when you need to browse directories or perform repeated interactive transfers. OpenSSH behavior and protocol details have evolved across versions, so scp should not be treated as a complete replacement for every SFTP workflow.

Using rsync over SSH

For repeated directory synchronization, use:

rsync -avz -e ssh ./local-folder/ username@server.example.com:/remote/folder/

rsync is efficient for mirroring changes, but it is not a beginner-friendly graphical client and requires suitable remote command execution support.

Which SFTP option is right for your Ubuntu computer?

Situation	Recommendation
Ubuntu Server, minimal installation, or terminal user	Install and use OpenSSH sftp
Desktop user who wants drag-and-drop transfers	Install FileZilla and select SFTP in Site Manager
Occasional transfer from a compatible desktop file manager	Try an sftp:// location, recognizing that labels vary
Repeated synchronization of changing directories	Use rsync over SSH
New deployment or internet-facing legacy machine	Upgrade Ubuntu first, then install the client on the supported release

For most administrators maintaining an old Ubuntu server, the shortest reliable path is openssh-client. For a desktop user who wants visual file management, FileZilla is the practical alternative. In either case, verify the server identity, use the correct port and authentication method, and confirm remote permissions before transferring or deleting files.

Frequently Asked Questions

Is SFTP the same as FTP?

No. SFTP is a file-transfer protocol that operates through SSH, while FTP and FTPS are different protocols. In FileZilla, select “SFTP – SSH File Transfer Protocol” when connecting to an SSH/SFTP server.

Do I need openssh-server to connect to an SFTP server?

No. You need the `openssh-client` package to connect from Ubuntu to a remote SFTP server. The separate `openssh-server` package is only needed when other computers must connect into your Ubuntu machine.

What port does SFTP use on Ubuntu?

SFTP normally uses SSH TCP port 22, but the remote administrator can configure a different port. Use the capital `-P` option with the command-line client, such as `sftp -P 2222 username@server.example.com`.

Can I connect to SFTP with a private key?

Yes. Specify the key with `sftp -i ~/.ssh/id_ed25519 username@server.example.com`, and ensure the key has appropriate local permissions such as `chmod 600 ~/.ssh/id_ed25519`. The server must be configured to accept that key and account.

Why does apt update fail on Ubuntu 16.04 or 18.04?

Ubuntu 16.04 and 18.04 are legacy releases, and their normal repositories may no longer be available on the standard mirrors. Consult Ubuntu’s EOL repository guidance or, preferably, upgrade the operating system; do not disable package signature verification or use unrelated repositories.

The Bottom Line

For a command-line SFTP client on Ubuntu 16.04 or 18.04, install openssh-client with sudo apt update and sudo apt install openssh-client, then connect with sftp username@server.example.com. Install FileZilla when you need a GUI, but choose SFTP explicitly. Because both Ubuntu releases are beyond standard support, upgrade whenever possible instead of building a new system on them.

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