# How to use Downloads.download() with SFTP?

**URL:** <https://discourse.julialang.org/t/how-to-use-downloads-download-with-sftp/76480>\
**Category:** Web Stack\
**Tags:** question\
**Created:** [February 15, 2022, 10:22am UTC](https://discourse.julialang.org/t/how-to-use-downloads-download-with-sftp/76480 "2022-02-15T10:22:03Z")\
**Posts on this page:** 18\
**Page:** 1

<div class="post-metadata">

**Author:** ![Fred](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/fred/32/14175_2.png) [@Fred](https://discourse.julialang.org/u/Fred)\
**Post date:** [February 15, 2022, 10:22am UTC](https://discourse.julialang.org/t/how-to-use-downloads-download-with-sftp/76480/1 "2022-02-15T10:22:03Z")

</div>

Hi,  
Is it possible to do SFTP with Julia ? I use filezilla to download files on a remote computer but I do not manage to access it with Julia. Is there something wrong in the URL format ?  
Thanks for your reply !

```julia
using Downloads
WARNING: using Downloads.download in module Main conflicts with an existing identifier.

Downloads.download("sftp://user@xx.xx.xx.xx:22/home/user/file.csv")
ERROR: Error in the SSH layer while requesting user@xx.xx.xx.xx:22/home/user/file.csv
Stacktrace:
  [1] (::Downloads.var"#9#18"{IOStream, Base.DevNull, Nothing, Vector{Pair{String, String}}, Float64, Nothing, Bool, Bool, String, Int64, Bool, Bool})(easy::Downloads.Curl.Easy)
    @ Downloads ~/Documents/logiciels/julia-1.7.1/share/julia/stdlib/v1.7/Downloads/src/Downloads.jl:369
  [2] with_handle(f::Downloads.var"#9#18"{IOStream, Base.DevNull, Nothing, Vector{Pair{String, String}}, Float64, Nothing, Bool, Bool, String, Int64, Bool, Bool}, handle::Downloads.Curl.Easy)
    @ Downloads.Curl ~/Documents/logiciels/julia-1.7.1/share/julia/stdlib/v1.7/Downloads/src/Curl/Curl.jl:64
  [3] #8

```

---

<div class="post-metadata">

**Author:** ![oheil](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/oheil/32/220745_2.png) [@oheil](https://discourse.julialang.org/u/oheil)\
**Post date:** [February 15, 2022, 10:58am UTC](https://discourse.julialang.org/t/how-to-use-downloads-download-with-sftp/76480/2 "2022-02-15T10:58:34Z")

</div>

libcurl is used and it’s sometimes not easy to find the problem.  
Let us know what

```julia
Downloads.download("sftp://user@xx.xx.xx.xx:22/home/user/file.csv", verbose=true )

```

gives you back additionally.

---

<div class="post-metadata">

**Author:** ![Fred](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/fred/32/14175_2.png) [@Fred](https://discourse.julialang.org/u/Fred)\
**Post date:** [February 15, 2022, 11:04am UTC](https://discourse.julialang.org/t/how-to-use-downloads-download-with-sftp/76480/3 "2022-02-15T11:04:02Z")

</div>

Thank you ! there is a .netrc that I never modified…

```julia
julia> Downloads.download("user@xx.xx.xx.xx:22/home/fred/file.csv",verbose=true)
* Couldn't find host xx.xx.xx.xx in the .netrc file; using defaults
* Trying xx.xx.xx.xx:22...
* Connected to xx.xx.xx.xx (xx.xx.xx.xx) port 22 (#0)
* Found host xx.xx.xx.xx in /home/user/.ssh/known_hosts
* Set "ssh-ed25519" as SSH hostkey type
* Closing connection 0

```

---

<div class="post-metadata">

**Author:** ![oheil](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/oheil/32/220745_2.png) [@oheil](https://discourse.julialang.org/u/oheil)\
**Post date:** [February 15, 2022, 11:15am UTC](https://discourse.julialang.org/t/how-to-use-downloads-download-with-sftp/76480/4 "2022-02-15T11:15:06Z")

</div>

The .netrc is fine, but perhaps it is the hostkey type ssh-ed25519 which libcurl doesn’t like.  
Check:

```julia
ssh-keyscan xx.xx.xx.xx

```

It will give a list of keys available by the server.  
If there is a ssh-rsa key you can force this one by removing the current entry of xx.xx.xx.xx in ~/.ssh/known\_hosts and adding the ssh-rsa key.

I am only guessing, so no guaranty that we are even on the right path.

---

<div class="post-metadata">

**Author:** ![Fred](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/fred/32/14175_2.png) [@Fred](https://discourse.julialang.org/u/Fred)\
**Post date:** [February 15, 2022, 12:10pm UTC](https://discourse.julialang.org/t/how-to-use-downloads-download-with-sftp/76480/5 "2022-02-15T12:10:44Z")

</div>

@oheil thank you for your advices !  
It seems very complicated… I will continue with FileZilla 🙂

if I remove the current entry of xx.xx.xx.xx in ~/.ssh/known\_hosts

```julia
* Connected to xx.xx.xx.xx (xx.xx.xx.xx) port 22 (#0)
* Did not find host xx.xx.xx.xx in /home/user/.ssh/known_hosts
* Failure establishing ssh session: -5, Unable to exchange encryption keys
* Closing connection 0
ERROR: Failure establishing ssh session: -5, Unable to exchange encryption keys while requesting sftp://user@xx.xx.xx.xx:22/home/user/file.csv

```

if I add the key, the the previous error appears

```julia
* Couldn't find host xx.xx.xx.xx in the .netrc file; using defaults
* Trying xx.xx.xx.xx:22...
* Connected to xx.xx.xx.xx (xx.xx.xx.xx) port 22 (#0)
* Found host xx.xx.xx.xx in /home/user/.ssh/known_hosts
* Set "ssh-ed25519" as SSH hostkey type
* Closing connection 0
ERROR: Error in the SSH layer while requesting sftp://user@xx.xx.xx.xx:22/home/user/file.csv
Stacktrace:
  [1] (::Downloads.var"#9#18"{IOStream, Base.DevNull, Nothing, Vector{Pair{String, String}}, Float64, Nothing, Bool, Bool, String, Int64, Bool, Bool})(easy::Downloads.Curl.Easy)
    @ Downloads ~/Documents/logiciels/julia-1.7.1/share/julia/stdlib/v1.7/Downloads/src/Downloads.jl:369

```

I think that the problem comes from my `sshd_config` set for `RSA` keys and not `ed25519`

```julia
PubkeyAuthentication yes
PubkeyAcceptedAlgorithms +ssh-rsa

```

it seems that Julia needs `ed25519` keys…

---

<div class="post-metadata">

**Author:** ![oheil](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/oheil/32/220745_2.png) [@oheil](https://discourse.julialang.org/u/oheil)\
**Post date:** [February 15, 2022, 12:35pm UTC](https://discourse.julialang.org/t/how-to-use-downloads-download-with-sftp/76480/6 "2022-02-15T12:35:19Z")

</div>

Yes, it is complicated.  
I have the same problem (at least exact same error) reproduced with one of my servers, but until now didn’t found a solution. Above was one of the steps I had to do until the “Error in the SSH layer…” error.  
Something in libssh2 which comes with Julia, but not yet any hint what…

---

<div class="post-metadata">

**Author:** ![oheil](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/oheil/32/220745_2.png) [@oheil](https://discourse.julialang.org/u/oheil)\
**Post date:** [February 15, 2022, 1:54pm UTC](https://discourse.julialang.org/t/how-to-use-downloads-download-with-sftp/76480/7 "2022-02-15T13:54:15Z")

</div>

What I missed before, did you provide a password, like:

```julia
Downloads.download("sftp://user:password@xx.xx.xx.xx:22/home/user/file.csv")

```

---

<div class="post-metadata">

**Author:** ![Fred](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/fred/32/14175_2.png) [@Fred](https://discourse.julialang.org/u/Fred)\
**Post date:** [February 15, 2022, 2:09pm UTC](https://discourse.julialang.org/t/how-to-use-downloads-download-with-sftp/76480/8 "2022-02-15T14:09:44Z")

</div>

@oheil, I tried with the password but still have `Error in the SSH layer`🙂

---

<div class="post-metadata">

**Author:** ![oheil](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/oheil/32/220745_2.png) [@oheil](https://discourse.julialang.org/u/oheil)\
**Post date:** [February 16, 2022, 4:15pm UTC](https://discourse.julialang.org/t/how-to-use-downloads-download-with-sftp/76480/9 "2022-02-16T16:15:44Z")

</div>

I think it’s a bug in `...\share\julia\stdlib\v1.7\Downloads\src\Curl\Easy.jl`:

```julia
const PROTOCOL_STATUS = Dict{String,Function}(
    ...
    "rtsp" => status_2xx_ok,
    "scp" => status_zero_ok,
    "sftp" => status_2xx_ok,
    "smtp" => status_2xx_ok,
    ...
)

```

For `"sftp"` it should be `status_zero_ok`. (see [libcurl example - sftpget.c](https://curl.se/libcurl/c/sftpget.html)) I will create an issue and perhaps a PR.

But there is more:

My first attempt with the host key of type ssh-ed25519 was right. According to libssh2 docs [https://www.libssh2.org/](https://www.libssh2.org/) only

- **Hostkey Types** : ssh-rsa, ssh-dss

are supported. So you have to force `ssh-rsa` or `ssh-dss` host keys using your `~/.ssh/known_hosts` file. `ssh-rsa` is clearly preferred over `dss`.  
Add an entry to `~/.ssh/known_hosts` using

```julia
ssh xx.xx.xx.xx

```

If it’s not asking to add it it’s already there.  
Use

```julia
ssh-keyscan xx.xx.xx.xx

```

to receive an `ssh-rsa` key and edit `~/.ssh/known_hosts` by removing the existing non-rsa key with the `ssh-rsa` key.

For me this was not enough.

My user name contains a `@` because it’s of the form `user@domain`. And the password has another problematic character which was `#`:  
User: `xxx@domain.com`  
Pass: `fsfsdf#`  
With this, I have to encode the problematic characters using html entities:  
`@ = %40`  
`# = %23`  
With that the following URL works:

```julia
Downloads.download(
    "sftp://xxx%40domain.com:fsfsdf%23@xx.xx.xx.xx/path/file.csv",
    "./file.csv"
)

```

but the local file `./file.csv` is deleted after successful download, because the return value of 0 is interpreted as an error state, which is the sftp specific bug.

You can overcome this until the bug is fixed with:

```julia
julia> using Downloads

julia> Downloads.Curl.PROTOCOL_STATUS["sftp"]=Downloads.Curl.status_zero_ok
status_zero_ok (generic function with 1 method)

julia> Downloads.download("sftp://user:pass@xx.xx.xx.xx/path/file.csv","./file.csv")

```

---

<div class="post-metadata">

**Author:** ![oheil](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/oheil/32/220745_2.png) [@oheil](https://discourse.julialang.org/u/oheil)\
**Post date:** [February 16, 2022, 4:26pm UTC](https://discourse.julialang.org/t/how-to-use-downloads-download-with-sftp/76480/10 "2022-02-16T16:26:27Z")

</div>

[https://github.com/JuliaLang/Downloads.jl/pull/180](https://github.com/JuliaLang/Downloads.jl/pull/180)

---

<div class="post-metadata">

**Author:** ![oheil](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/oheil/32/220745_2.png) [@oheil](https://discourse.julialang.org/u/oheil)\
**Post date:** [February 16, 2022, 4:56pm UTC](https://discourse.julialang.org/t/how-to-use-downloads-download-with-sftp/76480/11 "2022-02-16T16:56:42Z")

</div>

Here is some additional information on how to get debug feedback from the libssh2 library.

Building Julia from source is straight forward and works well (here I used a debian WSL2 in Windows 10)  
Getting source via git from `https://github.com/JuliaLang/julia#master` which creates a new folder `julia`:

```julia
cd julia
export USE_BINARYBUILDER_LIBSSH2=0
export USE_BINARYBUILDER_CURL=0
make

```

Edit file `./deps/srccache/curl-7.73.0/lib/vssh/libssh2.c` (the path may change over time with version change of curl) and uncomment the following line at the beginning so that it is

```julia
#define CURL_LIBSSH2_DEBUG

```

Edit file `deps/libssh2.mk` and change `Release` to `Debug`, so that it is:

```julia
LIBSSH2_OPTS := $(CMAKE_COMMON) -DBUILD_SHARED_LIBS=ON -DBUILD_EXAMPLES=OFF \
                -DCMAKE_BUILD_TYPE=Debug

```

Now build again:

```julia
rm -rf deps/scratch/curl*
rm -rf deps/scratch/libssh2*
make

```

The resulting `julia` binary will give plenty information output from libssh2 via the [libssh2\_trace()](https://www.libssh2.org/libssh2_trace.html) API.

---

<div class="post-metadata">

**Author:** ![Fred](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/fred/32/14175_2.png) [@Fred](https://discourse.julialang.org/u/Fred)\
**Post date:** [February 16, 2022, 7:11pm UTC](https://discourse.julialang.org/t/how-to-use-downloads-download-with-sftp/76480/12 "2022-02-16T19:11:57Z")

</div>

wow ! very impressive debugging ! 😉  
I almost suceded after removing non-RSA keys :

```julia
Downloads.Curl.PROTOCOL_STATUS["sftp"]=Downloads.Curl.status_zero_ok
status_zero_ok (generic function with 1 method)

* Connected to xx.xx.xx.xx (xx.xx.xx.xx) port 22 (#0)
* Found host xx.xx.xx.xx in /home/user/.ssh/known_hosts
* Set "ssh-rsa" as SSH hostkey type
* Failure establishing ssh session: -5, Unable to exchange encryption keys
* Closing connection 0

```

---

<div class="post-metadata">

**Author:** ![oheil](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/oheil/32/220745_2.png) [@oheil](https://discourse.julialang.org/u/oheil)\
**Post date:** [February 16, 2022, 8:13pm UTC](https://discourse.julialang.org/t/how-to-use-downloads-download-with-sftp/76480/13 "2022-02-16T20:13:19Z")

</div>

If you have access to the server or to server admin you can ask or look, if the server supports one of the following:

```julia
* **Key Exchange Methods** : diffie-hellman-group1-sha1, diffie-hellman-group14-sha1, 
         diffie-hellman-group-exchange-sha1, 
         diffie-hellman-group-exchange-sha256
* **Ciphers** : aes256-ctr, aes192-ctr, aes128-ctr, 
         aes256-cbc (rijndael-cbc@lysator.liu.se), aes192-cbc, 
         aes128-cbc, 3des-cbc, blowfish-cbc, cast128-cbc, 
         arcfour, arcfour128, none

```

again from [https://www.libssh2.org/](https://www.libssh2.org/)  
I am not sure if the error is about Key exchange method or the Ciphers.

---

<div class="post-metadata">

**Author:** ![oheil](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/oheil/32/220745_2.png) [@oheil](https://discourse.julialang.org/u/oheil)\
**Post date:** [February 16, 2022, 8:28pm UTC](https://discourse.julialang.org/t/how-to-use-downloads-download-with-sftp/76480/14 "2022-02-16T20:28:26Z")

</div>

Or you can try with a sftp client and option -v :

```julia
sftp -v sftp://user@xx.xx.xx.xx/

```

It prints also some usefull information about key exchage algorithms (kex) and more.  
You can also force a cipher with option -c:

```julia
sftp -v -c aes256-ctr sftp://user@xx.xx.xx.xx/

```

gives for example:

```julia
...
debug1: kex: server->client cipher: aes256-ctr MAC: umac-64-etm@openssh.com compression: none
debug1: kex: client->server cipher: aes256-ctr MAC: umac-64-etm@openssh.com compression: none
d
...

```

Well, I admit, it’s tedious.

---

<div class="post-metadata">

**Author:** ![Fred](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/fred/32/14175_2.png) [@Fred](https://discourse.julialang.org/u/Fred)\
**Post date:** [February 17, 2022, 8:05am UTC](https://discourse.julialang.org/t/how-to-use-downloads-download-with-sftp/76480/15 "2022-02-17T08:05:35Z")

</div>

Thank you @oheil !  
SFTP (and fileZila) password authentification works very well. Indeed key exchange is tried first and fail, this is why password authentification is finally selected. It seems that Julia `download()` function is much more picky…

```julia
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug1: Authentications that can continue: publickey,password
debug1: Next authentication method: publickey
debug1: Offering public key: /home/user/.ssh/id_rsa RSA SHA256:XE...
debug1: Authentications that can continue: publickey,password
debug1: Trying private key: /home/user/.ssh/id_dsa
debug1: Trying private key: /home/user/.ssh/id_ecdsa
debug1: Trying private key: /home/user/.ssh/id_ecdsa_sk
debug1: Trying private key: /home/user/.ssh/id_ed25519
debug1: Trying private key: /home/user/.ssh/id_ed25519_sk
debug1: Trying private key: /home/user/.ssh/id_xmss
debug1: Next authentication method: password
user@xx.xx.xx.xx's password: 
debug1: Enabling compression at level 6.
Authenticated to xx.xx.xx.xx ([xx.xx.xx.xx]:22) using "password".

```

---

<div class="post-metadata">

**Author:** ![oheil](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/oheil/32/220745_2.png) [@oheil](https://discourse.julialang.org/u/oheil)\
**Post date:** [February 17, 2022, 8:21am UTC](https://discourse.julialang.org/t/how-to-use-downloads-download-with-sftp/76480/16 "2022-02-17T08:21:12Z")

</div>

The authentication methods are tried until one succeeds or none is left.  
It’s the same for Julias download as it is done by libssh2.

Your snippet is not the right part for your issue.  
You need to look for host keys, kex and ciphers. Those tell you, which your client (or filezille) is able to choose for your server. Your client and the server are negotiating them.  
If it is something, which libssh2 doesn’t support, it would be a hint on whats going on.

---

<div class="post-metadata">

**Author:** ![stene](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/stene/32/26044_2.png) [@stene](https://discourse.julialang.org/u/stene)\
**Post date:** [September 15, 2023, 2:23pm UTC](https://discourse.julialang.org/t/how-to-use-downloads-download-with-sftp/76480/17 "2023-09-15T14:23:38Z")

</div>

Fixed (most) of the issues you were having: [Julia SFTP Client](https://github.com/stensmo/SFTPClient.jl)

---

<div class="post-metadata">

**Author:** ![stene](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/stene/32/26044_2.png) [@stene](https://discourse.julialang.org/u/stene)\
**Post date:** [April 6, 2025, 1:47pm UTC](https://discourse.julialang.org/t/how-to-use-downloads-download-with-sftp/76480/18 "2025-04-06T13:47:31Z")

</div>

Posting code example:

```julia
using SFTPClient

# Replace with your actual credentials
  username = "demo"
  password = "password"
  url = "sftp://test.rebex.net/pub/example/"

  file_name = "file.csv"

  sftp = SFTP(url, username, password)

try
    SFTPClient.download(sftp, file_name;downloadDir=".")
    println("File downloaded successfully! $(file_name)")
catch e
    println("Error downloading file: ", e)
end

```