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Sia Skynet FAQs

Common questions and answers related to Sia Skynet.

Notice: Skynet continues to be developed - information will be added as it becomes available and new features are implemented.

Looking for topics related to the Sia-UI and Wallet, standard Sia Renting, or Hosting? We also have general information on Skynet, a Guide to Using Sia Skynet, and a List of Skynet Portals for Skynet users.

This page was last updated on March 4, 2021 with Sia version 1.5.0. Not all FAQ entries may have been updated, but we make an effort to look over each entry and make relevant changes with each update.


What is the Sia Skynet?

Skynet is a component of Sia which allows users to share files stored on the Sia storage network with other people. Normally, Sia file uploads as a renter are private and encrypted - Skynet uploads are unencrypted, and publicly accessible through Skylinks. This is facilitated through normal Sia renting and hosting, and public websites called Portals.

For more information on Skynet and its components, see our Skynet section.

How long do files stay on Skynet?

The amount of time a file remains available on Skynet depends on how the file was uploaded, and if the file is re-pinned.

Skynet files are stored using normal Sia storage, so contracts are negotiated for storage the same way as normal renting. The default Sia renting contract window is about 3 months, so this would be how long a Skynet file would be stored if you uploaded it with your Sia client using default settings. Just like normal Sia renting, if you open your Sia client every month or so, the contracts on your pinned files will renew, and the file could be kept online indefinitely as long as you continue to fund and renew the contracts.

Public Skynet Portal operators who allow users to upload files for free may have different default settings for how long files are stored - look for information on each Portal website or contact the Portal operator if you're not sure.

Once a file is uploaded to Skynet, it can be re-pinned by anyone to extend the storage time. The person who re-pins the file assumes the storage costs for a copy of the file, and for the contract duration on the copied file. Multiple people could be paying for multiple copies of the same file to ensure that it stays online, and the file would continue to be accessible under one single Skylink. For more information on pinning, see our Skynet section.

Are all files on Skynet publicly accessible?

By default, yes. Skynet files are stored unencrypted and in one piece on hosts, and anyone with a Skylink to a file can view the file. While it would be difficult for someone to guess a specific Skylink ID, it should not be considered impossible. Additionally, uploading data to Skynet via a public Skynet Portal exposes the information to the Portal operator, who may be viewing the information, indexing your Skylink, or something else. As such, sensitive or private data should not be stored on Skynet.

Skynet has the ability to control encryption of and access to Skynet files, but this is not yet implemented in the majority of public Skynet Web Portals because the portal needs to know the encryption key for the content. One alternate option is to encrypt content yourself before uploading, and share the encryption key or password with your recipient outside of Skynet.

What if I want to store my files on Skynet privately, and not share them with others?

You would be better off using Sia as a standard renter. Skynet is designed to share files with others, or to provide access to files outside of your private Sia installation. See our section on Renting on Sia for more information on renting non-Skynet Sia storage.

If you're interested in being able to share files using Skynet and keep them encrypted on host storage, see this FAQ topic.

Skynet Usage

Does using Skynet cost anything? Who pays for it if so?

Yes - Skynet is a proxy for interacting with the Sia network, so normal storage and bandwidth costs apply.

  • If you upload data to Skynet via your own Sia client as a renter, you pay for the storage costs of storing the file, as well as the upload bandwidth costs, just like a normal renter. If you pin an existing Skynet link with your own Sia client, it is copied to your Sia renter storage, so you also pay storage costs on a pinned file as a normal renter would.
  • If you upload data to Skynet using a public Skynet Portal, the Portal operator typically assumes the cost of storing and uploading your file.
  • A Skynet Portal is used to access and download your file, so the Portal operator assumes the cost for download bandwidth.
  • Portal operators also incur around $10/month in fees related to contracts necessary for Portal operation.

Currently, all public Skynet Portals operate at no cost to users. The Portal operators assume all costs for using the Portal and uploading and downloading files. It is possible that in the future, Portals will be developed with a premium model in order to cover Portal operation costs.

What are the file size limitations for Skynet?

Most public Skynet Web Portals allow you to upload 1GB files for free. Some Portals have upload limits as high as 10GB. If you're uploading files from your own Sia instance to Skynet, the practical file size limitation is currently around 400GB.

Note that by default, Skynet files are stored in one piece at 10x redundancy, so a 1GB file on Skynet will actually consume 10GB of space on Sia and will incur 10GB worth of storage costs if you are uploading the file and paying for it via your own Sia instance. The Skynet atomic filesize is 4MB, so files smaller than 4MB will be padded to that size, similar to how regular Sia storage works as a renter.

How do I use Skynet to upload or download files?

This is explained in our Guide to Using Sia Skynet.

How do I view the files I've uploaded to Skynet?

The Sia-UI does not yet show files you've uploaded to Skynet in your Rent tab - the UI has no graphical support for Skynet as of v1.4.8. You can view your Skynet files using the Terminal by clicking the Terminal (>) icon at the top of Sia-UI and typing skynet ls. Your uploaded files and Skylinks will be displayed. You can also use siac skynet ls.

If you've uploaded files to Skynet using a public Skynet Web Portal, there's no way to see a history of your files unless the Web Portal operator has implemented such functionality. You'll have to keep track of your Skylinks on your own.

The original uploader of a file or folder to Skynet is the first person to "pin" it. Pinning is what makes content available to others on Skynet, and creates a Skylink which can be used to view the content. You may come across content on Skynet which you want to keep online even if the original uploader unpins it, or stops paying the storage fees on it. You can do this by re-pinning a file, which copies it to your Sia renter storage and provides another point of redundancy for the file. You will then pay the storage costs for your copy of the file, and it will stay online at its original Skylink. The file will stay online as long as at least one person keeps it pinned and pays the storage costs for the file.

Instructions on how to re-pin a file are provided in our Guide to Using Sia Skynet.

You can un-pin a Skylink by using siac skynet unpin [skypath], replacing [skypath] with the path to the file in your Skynet storage. See this FAQ topic for details on how to see your current Skylinks and files if you don't know the path to a file or Skylink you've uploaded or pinned. You could also use the Sia-UI Terminal and skynet unpin [skypath], but the Terminal doesn't support spaces in file paths so it may not work for some files. See this FAQ topic to learn more about siac and where to find it if you're not familiar with how to use it.

Note that you cannot un-pin a file completely if others have re-pinned it, nor can you un-pin somebody else's file (unless you are a Portal operator and the file was originally uploaded through your Portal - then it's technically your file). As long as one person keeps a Skylink pinned, it will remain online.

Can I encrypt files uploaded to Skynet? What are the limitations?

Skynet encryption has been implemented as of Sia v1.4.8, documentation on which can be found here. It entails creating a Skykey (an encryption key) which can be loaded into a Portal to allow files to be encrypted or decrypted through that Portal. This currently requires that the encryption key be known to any Portal used to download encrypted files, but in the future this will likely change. This is an area which continues to be developed.

Alternately, you can encrypt files before you upload them to Skynet, and share the decryption key and Skylink directly with anyone you wish to have access to the file.

Skynet Portals

What is a Skynet Portal? What is a Web Portal? What's the difference?

A Skynet Portal is a Sia instance configured to run in Portal mode, which causes it to form contracts with as many Sia hosts as it can find in order to be able to ask each host if they have a particular Skylink. Under this configuration, Skylinks can be retrieved through the Sia instance through the Sia Daemon API.

A Skynet Web Portal is a front-end website which allows you to access content on Skynet via Skylinks through a web browser. Web Portals connect to a Sia instance configured as a Portal, as explained above. A public stock Web Portal has been provided by Nebulous which provides basic Skynet upload and download capabilities through a website.

Default Skynet Web Portals allow users to both upload and download Skynet content. Most Portal operators cover the storage and bandwidth costs for storing and retrieving files on the Sia network. However, Portals can also be modified by an operator with asthetic or other changes. Portals could be run privately, or outfitted with access controls to only allow certain users to access them. As of March 2021, the majority of public portals are free and run by supporters of the Sia project.

A current list of known Skynet Portals can be found on our Skynet Portal List page.

Do I need to run my own Skynet Portal to use Skynet?

Not as long as public portals exist to retrieve your files, no. You can upload files to Skynet with a standard Sia client, but for other people to access them, they must be retrieved through a Portal. A number of free Skynet Web Portals exist which allow you to retrieve any Skynet file if you have the Skylink to the file. Currently, there is no indication that free public Skynet Portals will stop existing.

You may consider running your own Portal if you need to ensure that your Skynet files are always accessible to others, if you need to restrict access to the content you upload and share, or if you simply wish to have your own private access to the Skynet network. If you run the Web Portal interface on a public server, you may want to consider securing it behind some form of authentication, or implement user access permissions by modifying the Portal software. You could also simply run a private Portal locally, with or without the web interface. Running your own Portal also incurs around $10/month in additional fees related to required Portal functionality and contracts.

Note that running a public Skynet Web Portal may have serious legal risks and liability concerns - see this FAQ topic for more information. Private Portals likely do not have these concerns, though you may risk stumbling across content you do not wish to view depending on how you use your Portal. Instructions on setting up your own Portal, both public and private, are provided in our Guide to Using Sia Skynet.

How do I set up my own Skynet Portal?
Warning: Running a public Skynet Portal may have serious legal risks and liability concerns - see this FAQ topic for more information.

Please see the section in our Guide to Using Sia Skynet on setting up your own Skynet Portal.

Skynet Apps (Skapps)

What is a Skynet App / Skapp?

A "skapp", or Skynet App, is an application which is self-contained on Skynet. Most Skapps are some form of website able to store and retrieve other content on Skynet dynamically. Examples include the Skynet App Store, an "app store" where people can post other Skapps, and SkyGallery, an image gallery.

Legal and Liability

Please note that the information provided below is for general reference only. It is not intended to be legal advice. If you have any legal concerns, please consult an appropriately qualified attorney or other legal counsel.

Are there any legal or liability concerns for a public Skynet Portal operator to consider?

Yes. Operating a public Skynet portal is essentially giving anonymous Internet strangers a gateway to upload and download any manner of data. This could include illegal content, such as copyrighted works, or much worse. As a Portal operator, this information will pass through your Portal and your server/system when it is uploaded and downloaded. From a technical standpoint and to anyone that doesn't know better, it will appear that you are the one hosting and storing the content, even though the content actually resides on the Sia storage network and on other Sia hosts.

You may receive takedown notices from copyright holders, or become the subject of a law enforcement investigation if you are unlucky enough to handle illegal content from a Portal user. The default Portal implementation has no way to filter or moderate Skynet uploads and downloads, aside from a basic blacklisting function to prevent downloads per Skylink. However, nothing would stop a user from uploading the content again and creating a new Skylink - resulting in a game of whack-a-mole in terms of trying to ban each new link once brought to your attention. If you desired more advanced moderation functionality, you would need to design and implement it yourself.

You should not operate a public Skynet Portal without carefully considering your personal liability in doing so. It is suggested to consult a lawyer or other legal counsel and discuss your intentions to operate a public Skynet Portal, including the ramifications of handling illegal data as a public Portal operator, before putting your own public Skynet Portal online.

Don't see your question answered? Let us know and we'll see if we can add it to the FAQ.