Amazon S3

S3 Drive Icon

Transfer files to your S3 account and browse the S3 buckets and files in a hierarchical way. For a short overview of Amazon S3, refer to the Wikipedia article.


You must obtain the login credentials (Access Key ID and Secret Access Key) of your Amazon Web Services Account from the AWS Access Identifiers page. Enter the Access Key ID and Secret Access Key in the login prompt.

IAM User

You can also connect using IAM credentials that have the Amazon S3 Full Access template policy permissions attached and optionally the CloudFront Full Access. Make sure you are connecting with AWS4-HMAC-SHA256 signature version (see above).

Generic S3 Profiles

For use with third party S3 installations.


Connection profiles can be installed from Preferences → Profiles..

Authentication with signature version AWS4-HMAC-SHA256



It is discouraged to enable this option to connect plaintext to Amazon S3.

If you have an S3 installation without SSL configured, you need an optional connection profile to connect using HTTP only without transport layer security. You will then have the added option S3 (HTTP) in the protocol dropdown selection in the Connection and Bookmark panels.

The default port is 80.

  • Download the S3 (HTTP) profile for preconfigured settings.


The default port is 443.

  • Download the S3 (HTTPS) profile for preconfigured settings.

AWS Gov Cloud

S3 GovCloud (US-East)

Use the endpoint or install the connection profile

  • Download the S3 GovCloud (US-East) profile for preconfigured settings.

S3 GovCloud (Us-West)

Use the endpoint or install the connection profile

  • Download the S3 GovCloud (US-West) profile for preconfigured settings.

AWS China (Beijiing)

Connect to the region AWS China (Beijing)

  • Download the S3 China (Beijing) profile for preconfigured settings.

Connecting to a single bucket

Connecting to a bucket owned by you or even a third party is possible without requiring permission to list all buckets. You can access buckets owned by someone else if the ACL allows you to access it by either:

  • Specify the bucket you want to access in the hostname to connect to like <bucketname> Your own buckets will not be displayed but only this bucket contents

  • Set the Default Path in the bookmark to the bucket name. If you have permission you can still navigate one level up to display all buckets if the ACL allows.


No regional endpoint should be set while connecting to a single bucket. The endpoint will be determined automatically by querying the region of the bucket.

Connecting with OpenID Connect (OIDC) identity provider


  • Cyberduck 8.7.0 or later required

  • Mountain Duck 4.15.0 or later required

Connecting to AWS S3 with web identity federation using AWS Security Token Service (STS) is supported with connection profiles specifying configuration properties specific to your identity provider (IdP).


The usage of these connection profiles requires the configuration of an OpenID Connect (OIDC) identity provider and role and trust policy in AWS IAM.

The connection profiles connect using temporary security credentials from the AWS Security Token Service (STS) obtained using a web identity token from your OpenID Connect (OIDC) identity provider. Refer to Custom connection profile using OpenID Connect provider and AssumeRoleWithWebIdentity STS API.


AssumeRoleWithWebIdentity API from AWS Security Token Service (STS) is used to exchange the JSON Web Token with temporary security credentials. In addition to AWS, the following combinations of S3 & STS APIs with OpenID Connect (OIDC) have been tested:

  • Connect to MinIO S3 authenticating with MinIO STS and Keycloak (OIDC)

  • Connect to AWS S3 authenticating with AWS STS and Keycloak (OIDC)

Sample connection profiles for authorization with well known identity providers


When connecting the user is requested to enter the Role ARN of the IAM role that has a trust relationship configured with the identity provider in Identity and Access Management (IAM).

S3 with Azure Active Directory (Azure AD)
  • Download the AWS S3+STS & Azure Active Directory (Azure AD) profile for preconfigured settings

S3 with Google OpenID Connect
  • Download the AWS S3+STS & Google OpenID Connect profile for preconfigured settings

Connecting with Temporary Access Credentials (Token) from EC2

If you are running Cyberduck for Windows or Cyberduck CLI on EC2 and have setup IAM Roles for Amazon EC2 to provide access to S3 from the EC2 instance, you can use the connection profile below that will fetch temporary credentials from EC2 instance metadata service at to authenticate. Edit the profile to change the role name s3access to match your IAM configuration.

  • Download the S3 (Credentials from Instance Metadata) profile for preconfigured settings

Connecting Using Credentials from AWS Command Line Interface

Instead of providing Access Key ID and Secret Access Key, authenticate using credentials managed in ~/aws/credentials on macOS or %USERPROFILE%\.aws\credentials on Windows using third-party tools.

  • Download the S3 (Credentials from AWS Command Line Interface) profile for preconfigured settings.

You must provide configuration in the standard credentials property file ~/.aws/credentials on macOS or %USERPROFILE%\.aws\credentials on Windows as well as the config file ~/aws/config on macOS or %USERPROFILE%\.aws\config on Windows from AWS Command Line Interface. Configure a bookmark with the field titled Profile Name in ~/.aws/credentials matching the profile name from ~/.aws/credentials on macOS or %USERPROFILE%\.aws\credentials on Windows. The properties aws_access_key_id, aws_secret_access_key and aws_session_token are supported.

You might be interested in scripts maintained by third parties to facilitate managing credentials

AWS IAM Identity Center

For a SSO connection authenticating with AWS IAM Identity Center (Successor to AWS Single Sign-On), the properties sso_start_url, sso_account_id, and sso_role_name are required within the standard credentials property file ~/.aws/credentials (macOS) or %USERPROFILE%\.aws\credentials (Windows). The access key, secret key, and session token cached by AWS CLI are retrieved from ~/.aws/cli/cache on macOS or %USERPROFILE%\.aws\cli\cache on Windows.

To populate the correct cache locations follow these steps:

  1. Run the command aws sso login to populate ~/.aws/sso/cache on macOS or respectively %USERPROFILE%\.aws\sso\cache on Windows. This adds client secrets but doesn’t add any usable AWS credentials.

  2. Seed the second cache in ~/.aws/cli/cache on macOS or respectively %USERPROFILE%\.aws\cli\cache on Windows by running the command aws sts get-caller-identity. This adds the usable credentials to the location Cyberduck and Mountain Duck reads from.


You can also do this for a specific profile by adding --profile myProfile to the commands. Make sure to use the same profile for both steps.

Connecting Using AssumeRole from AWS Security Token Service (STS)

Instead of providing Access Key ID and Secret Access Key, authenticate using temporary credentials from AWS Security Token Service (STS) with optional Multi-Factor Authentication (MFA). Refer to Using IAM Roles.

MFA Token Prompt

You must provide configuration in the standard credentials property file ~/.aws/credentials on macOS or %USERPROFILE%\.aws\credentials on Windows from AWS Command Line Interface. Configure a bookmark with the field titled Profile Name in ~/.aws/credentials matching the profile name from ~/.aws/credentials on macOS or %USERPROFILE%\.aws\credentials on Windows with the role_arn configuration.

Example Configuration

Refer to Assuming a Role.

aws_access_key_id=<access key for testuser>
aws_secret_access_key=<secret key for testuser>

Read Credentials from ~/.aws/credentials

When editing a bookmark, the Access Key ID is set from the default profile in the credentials file located at ~/.aws/credentials on macOS or %USERPROFILE%\.aws\credentials on Windows if such a profile exists.

Connecting without using AWS credentials

Use the S3 (HTTPS) connection profile to access public data sets on AWS Open Data without using access keys by using the Anonymous Login option in the bookmark configuration.

S3 Anonymous Login
  • Download the S3 (HTTPS) profile for preconfigured settings

Cyberduck CLI

List all buckets with Cyberduck CLI using

duck --username <Access Key ID> --list s3:/

List the contents of a bucket with

duck --username <Access Key ID>  --list s3:/<bucketname>/

Refer to the Cyberduck CLI documentation for more operations.

Uploads using CLI

Add default metadata for uploads using the preferences option to read from the environment. The property is documented in Default metadata.

env "s3.metadata.default=Content-Type=application/xml" duck --upload …

Set a default ACL for the upload with

env "s3.acl.default=public-read" duck --upload …

Third-Party Providers

There are a growing number of third parties besides Amazon offering S3 compatible cloud storage software or solutions. Here is a non-exhaustive list:


Creating a Bucket

To create a new bucket for your account, browse to the root and choose File → New Folder… (macOS ⌘N Windows Ctrl+Shift+N). You can choose the bucket location in Preferences (macOS ⌘, Windows Ctrl+,) → S3. Note that Amazon has a different pricing scheme for different regions.

Mountain Duck

You will receive a prompt for the region when creating a new bucket

Supported Regions

  • EU (Ireland)

  • EU (London)

  • EU (Paris)

  • EU (Stockholm)

  • US East (Northern Virginia)

  • US West (Northern California)

  • US West (Oregon)

  • Asia Pacific (Singapore)

  • Asia Pacific (Tokyo)

  • South America (São Paulo)

  • Asia Pacific (Sydney)

  • EU (Frankfurt)

  • US East (Ohio)

  • Asia Pacific (Seoul)

  • Asia Pacific (Mumbai)

  • Canada (Montreal)

  • China (Beijing)

  • China (Ningxia)

Create Bucket


  • Because the bucket name must be globally unique the operation might fail if the name is already taken by someone else (E.g. don’t assume any common name like media or images will be available).

  • You cannot change the location of an existing bucket.

Bucket Access Logging

When this option is enabled in the S3 panel of the Info (File → Info (macOS ⌘I Windows Alt+Return)) window for a bucket or any file within, available log records for this bucket are periodically aggregated into log files and delivered to /logs in the target logging bucket specified. It is considered best practice to choose a logging target that is different from the origin bucket.

AWS Logging Configuration

To toggle CloudFront access logging, select the the Distribution panel in the File → Info (macOS ⌘I Windows Alt+Return) window.

Requester Pays Buckets

Per default, buckets are accessed with the parameter x-amz-requester-payer in the header to allow access to files in buckets with the Requester Pays option enabled.

You can change the parameter using the following hidden configuration options.



Versioning can be enabled per bucket in File → Info (macOS ⌘I Windows Alt+Return) → S3. Make sure the user has the following permissions:

  • s3:PutBucketVersioning to permit users to modify the versioning configuration of a bucket.

  • s3:GetBucketVersioning and s3:ListBucketVersions to see versions of a file.

  • s3:GetObjectVersion to download a specific version.

You can view all revisions of a file in the browser by choosing View → Show Hidden Files.

Info → Versions

A list of file versions can be viewed in the Versions tab of the Info window. Files can be reverted to a chosen version of this list. Additionally, versions of the list can be deleted.


To revert to a previous version and make it the current, choose File → Revert.

Multi-Factor Authentication (MFA) Delete

To enable Multi-Factor Authentication (MFA) Delete, you need to purchase a compatible authentication device. Toggle MFA in File → Info (macOS ⌘I Windows Alt+Return) → S3. When enabled, you are prompted for the device number and one-time token in the login prompt. Never reenter a token in the prompt already used before. A token is only valid for a single request. Wait for the previous token to disappear from the device screen and request a new token from the device.

MFA Credentials



Creating a folder inside a bucket will create a placeholder object named after the directory, has no data content, and the MIME type application/x-directory. This is interoperable with folders created with AWS Management Console.


Do not name objects in S3 containing / as this will break navigation.

File Transfers

Transfer Acceleration

When enabled for the bucket, downloads, and uploads using the S3 Transfer Acceleration endpoints to transfer data through CloudFront’s globally distributed edge locations. The name of the bucket used for Transfer Acceleration must be DNS-compliant and must not contain periods (“.”). You do not need to enter transfer accelerated endpoints manually. When using Transfer Acceleration, additional data transfer charges may apply to connect to

Transfer Acceleration


Make sure the user has s3:GetAccelerateConfiguration permission permits users to return the Transfer Acceleration state of a bucket.


Files are verified both by AWS when the file is received and compared with the SHA256 checksum sent with the request. Additionally, the checksum returned by AWS for the uploaded file is compared with the checksum computed locally if enabled in Transfers → Checksum → Uploads → Verify checksum.

Multipart Uploads

Files larger than 100MB are uploaded in parts with up to 10 parallel connections as 10MB parts. Given these sizes, the file size limit is 100GB with a maximum of 10’000 parts allowed by S3. The number of connections used can be limited using the toggle in the lower right of the transfer window.

Multipart uploads can be resumed later when interrupted. Make sure the user has the permission s3:ListBucketMultipartUploads.

Unfinished Multipart Uploads

You can view unfinished multipart uploads in the browser by choosing View → Show Hidden Files.


You can set options with the following hidden configuration options.

Part size for multipart uploads


Threshold to use multipart uploads is set to 100MB by default


Storage Class

You have the option to store files using the Reduced Redundancy Storage (RRS) by storing non-critical, reproducible data at lower levels of redundancy. Set the default storage class in Preferences (macOS ⌘, Windows Ctrl+,) → S3 and edit the storage class for already uploaded files using File → Info (macOS ⌘I Windows Alt+Return) → S3. Available storage classes are

  • Regular Amazon S3 Storage

  • Intelligent-Tiering

  • Standard IA (Infrequent Access)

  • One Zone-Infrequent Access

  • Reduced Redundancy Storage (RRS)

  • Glacier

  • Glacier Deep Archive

Lifecycle Configuration

Specify after how many days a file in a bucket should be moved to Amazon Glacier or deleted.

Lifecycle Configuration

Restore from Glacier


This function is currently Cyberduck only.

You can temporarily restore files from Glacier and Glacier Deep Archive using File → Restore. The file will be restored using standard retrieval and expire 2 days after retrieval. Restoring takes some time and attempting to download an item not yet restored will lead to an error The operation is not valid for the object’s storage class.

Glacier Retrieval Options

You can set retrieval options for the storage classes Glacier and Glacier Deep Archive with the following hidden configuration options.

Sets Glacier retrieval tier at which the restore will be processed.


→ Valid values are Standard, Bulk, Expedited.

Sets the time, in days, between when an object is uploaded to the bucket and when it expires.


Restored Glacier files in Mountain Duck

Temporarily restored files from Glacier won’t change the storage class and therefore won’t be listed by Mountain Duck. To make restored Glacier files available in Mountain Duck make sure to change the file’s storage class in the S3 tab of the Cyberduck Info window.

Access Control (ACL)

Amazon S3 uses Access Control List (ACL) settings to control who may access or modify items stored in S3. You can edit ACLs in File → Info (macOS ⌘I Windows Alt+Return) → Permissions. Alternatively, permissions can be changed using bucket policies.


Canonical User ID Grantee

If you enter a user ID unknown to AWS, the error message S3 Error Message. Bad Request. Invalid id. will be displayed.

Email Address Grantee

If you enter an email address unknown to AWS, the error message S3 Error Message. Bad Request. Invalid id. will be displayed. If multiple accounts are registered with AWS for the given email address, the error message Bad Request. The e-mail address you provided is associated with more than one account. Please retry your request using a different identification method or after resolving the ambiguity. is returned.

All Users Group Grantee

You must give the group grantee read permissions for your objects to make them accessible using a regular web browser for everyone.

If bucket logging is enabled, the bucket ACL will have READ_ACP and WRITE permissions for the group grantee

Default ACLs

You can choose canned ACLs to be added to uploaded files or created buckets per default. Canned ACLs are predefined sets of permissions. The default ACL can be set within Preferences (macOS ⌘, Windows Ctrl+,) → S3 → Default ACL.

Applies to buckets

Applies to files







You can disable the ACLs using the Amazon S3 Object Ownership.


You need to set Preferences → S3 → Default ACL → None for uploads with disabled ACLs to succeed. Otherwise uploads fail with The bucket does not allow ACLs..


The following permissions can be given to grantees:




Allows grantee to list the files in the bucket

Allows grantee to download the file and its metadata


Allows grantee to create, overwrite, and delete any file in the bucket

Not applicable


Allows grantee all permissions on the bucket

Allows grantee all permissions on the object


Allows grantee to read the bucket ACL

Allows grantee to read the file ACL


Allows grantee to write the ACL for the applicable bucket

Allows grantee to write the ACL for the applicable file


You may receive an error Cannot change permissions of when attempting to grant Everyone READ permission for a file if the bucket has public access blocked because Block Public Access settings are turned on for this bucket.

Public URLs

You can access all URLs (including from CDN configurations) from the menu Edit → Copy URL and File → Open URL.

Copy URLs


Public URLs are only accessible if the permission READ is granted for EVERYONE.

Choose File → Share… to change the ACL on the file permanently allowing read for everyone. You can reset the changed ACL in Info → ACL.

Pre-signed Temporary URLs

A private object stored in S3 can be made publicly available for a limited time using a pre-signed URL. The pre-signed URL can be used by anyone to download the object, yet it includes a date and time after which the URL will no longer work. Copy the pre-signed URL from Edit → Copy URL→ Signed URL or File → Info (macOS ⌘I Windows Alt+Return) → S3.

There are pre-signed URLs that expire in one hour, 24 hours (using the preference s3.url.expire.seconds), a week, and a month. You can change the hidden preference s3.url.expire.seconds from the default 86400 (24 hours).


It is required that your AWS credentials are saved in keychain. Refer to Passwords.

Force use of AWS2 Signature

Using the AWS4 signature version used in Cyberduck version 5.0 and later, pre-signed URLs cannot have an expiry date later than a week. You can revert by setting the default signature version to AWS2 by using the S3 AWS2 Signature Version (HTTP) connection profile.


This deprecated signature version is not compatible with new regions such as eu-central-1.


Share links cannot be created when failing to update the ACLs on a file because

  • Bucket has “Object Ownership” set to “Bucket owner enforced” (ACLs disabled). Error message: This bucket does not allow ACLs

  • “Block public access” is enabled on bucket. Error message: Access denied


You can edit standard HTTP headers and add custom HTTP headers to files to store metadata. Choose File → Info (macOS ⌘I Windows Alt+Return) → Metadata to edit headers.

Default Metadata

Currently only possible using a hidden configuration option you can define default headers to be added for uploads. Multiple headers must be separated using a whitespace delimiter. Key and value of a header are separated with =. For example, if you want to add an HTTP header for Cache-Control and one named Creator you would set

s3.metadata.default="Cache-Control=public,max-age=86400 Creator=Cyberduck"

Cache Control Setting

This option lets you control how long a client accessing objects from your S3 bucket will cache the content and thus lowering the number of access to your S3 storage. In conjunction with Amazon CloudFront, it controls the time an object stays in an edge location until it expires. After the object expires, CloudFront must go back to the origin server the next time that edge location needs to serve that object. By default, all objects automatically expire after 24 hours when no custom Cache-Control header is set.

The default setting is Cache-Control: public,max-age=2052000 when choosing to add a custom Cache-Control header in the Info panel which translates to a cache expiration of one month (one month in seconds equals more or less 60*60*24*30).

Use the hidden configuration option s3.cache.seconds to set a custom default value




Use curl -I <http://<bucketname><key> to debug HTTP headers.

Server Side Encryption (SSE)

Server-side encryption for stored files is supported and can be enabled by default for all uploads in the S3 preferences or for individual files in the File → Info (macOS ⌘I Windows Alt+Return) → S3. AWS handles key management and key protection for you.


Choose Preferences → S3 → Server Side Encryption to change the default.

  • None will not encrypt files (Default).

  • SSE-S3 will encrypt files using AES-256 with a default key provided by S3.

  • SSE-KMS will encrypt files with the default key stored in AWS Key Management Service (KMS).

You can override these default settings in the File → Info (macOS ⌘I Windows Alt+Return) → S3 panel per bucket.

Server-Side Encryption with Amazon S3-Managed Keys (SSE-S3)

When changing the setting for a folder or bucket you are prompted to confirm the recursive operation on all files contained in the selected bucket or folder.

Server-Side Encryption with AWS KMS-Managed Keys (SSE-KMS)

Among the default SSE-S3 (AES-256), the server-side encryption (SSE) dropdown list allows choosing from all private keys managed in AWS Key Management Service (KMS).


This requires the kms:ListKeys and kms:ListAliases permission for the AWS credentials used to connect to S3.

AWS SSE-KMS Private Key Selection

When changing the setting for a folder or bucket you are prompted to confirm the recursive operation on all files contained in the selected bucket or folder.

Prevent Uploads of Unencrypted Files

Refer to the AWS Security Blog

CloudFront CDN

Amazon CloudFront delivers your static and streaming content using a global network of edge locations. Requests for your objects are automatically routed to the nearest edge location, so content is delivered with the best possible performance. Refer to Amazon CloudFront distribution for help about setting up distributions.

Website Configuration

To host a static website on S3, It is possible to define an Amazon S3 bucket as a Website Endpoint. The configuration in File → Info (macOS ⌘I Windows Alt+Return) → Distribution allows you to enable website configuration. Choose Website Configuration (HTTP) from Delivery Method and define an index document name that is searched for and returned when requests are made to the root or the subfolder of your website.

To access this website functionality, Amazon S3 exposes a new website endpoint for each region (US Standard, US West, EU, or Asia Pacific). For example, is the endpoint for the Asia Pacific Region. The location is displayed in the Where field following the Origin.

S3 Website Configuration

To configure Amazon CloudFront for your website endpoints, refer to Website Configuration Endpoint Distributions with CloudFront CDN.


Known Issues

Modification Date

The modification date retention is only supported using the S3 (Timestamps) profile. When using this connection profile, the modification and creation dates get written into the metadata in form of x-amz-meta-Mtime and x-amz-meta-Btime for files uploaded to S3. .

Listing folders will require an additional HEAD request for every file to read the modification date from the object metadata. This can cause performance issues due to the excessive number of requests required with large directory contents.


Make sure to enable Preserve modification date in Preferences → Transfers → Timestamps in Cyberduck.

The {download}`S3 (Timestamps) profile (Timestamps).cyberduckprofile is only necessary if you want to view the timestamps set in the browser.


The timestamp metadata is interoperable with rclone.

Disable use of Virtual Host Style Requests

Set the hidden preference s3.bucket.virtualhost.disable to true if your S3 compatible storage does only support path style requests to reference buckets. Alternatively a custom connection profile with the property set in Properties.

  • Download the S3 (Deprecated path style requests) profile for preconfigured settings.

Listing directory / failed. with path in custom S3 endpoint

When connecting to a service that requires a path prefix in all requests, you must set the Context property in a custom connection profile.

Moved Permanently but no Location Header

Make sure the IAM user has the permission s3:GetBucketLocation to read the bucket location.

Writing Files to S3 Compatible Third-Party Service Provider may Fail

The S3 interoperable service must support multipart uploads.

Delete Marker

When overwriting files some applications (like Windows File Explorer) will delete files prior to writing the new file. Thus we also forward this delete operation to S3 resulting in the delete marker being set. You can overwrite files with command-line tools which typically do not delete files prior to overwriting.

In, Creating a new Top-Level Folder in S3 Fails with Interoperability failure. Bucket name is not DNS compatible. Please contact your web hosting service provider for assistance.

A bucket name in S3 cannot have whitespace in the filename. Because a new folder created with is named Untitled Folder the operation fails. As a workaround, create a new bucket with mkdir in


The bucket can be created within the Smart Synchronization mode as the folder only gets uploaded after it is renamed. Make sure to choose a filename with no whitespace. For the additional restrictions of the bucket name, refer to the AWS bucket naming rules.

Saving a file in will Attempt to Create a Folder /Temporary Items on the Remote Volume. On some Servers, this may fail due to a Permission Failure or Because the Name of the Folder is not Allowed as in S3.

You will get the error message Bucket name is not DNS compatible. Please contact your web hosting service provider for assistance.. As of Mountain Duck version 2.1, .DS_Store files are only saved in a temporary location and not stored on the mounted remote volume.