Cannot connect to FTP server using Go but can connect using FileZilla - docker

Question

I have a small Golang program and I'm trying to connect to an FTP server running in a docker container (https://registry.hub.docker.com/r/atmoz/sftp).
My machine is a M1 Pro MacBook.
The container is started with the following command:
docker run -p 22:22 -d atmoz/sftp foo:pass:::upload
The Go version is 1.17.13.
The code code of the program is the following:
package main
import (
"log"
"time"
"github.com/jlaffaye/ftp"
)
func main() {
c, err := ftp.Dial("localhost:22", ftp.DialWithTimeout(5*time.Second))
if err != nil {
log.Fatal(err, " cannot connect")
}
err = c.Login("foo", "pass")
if err != nil {
log.Fatal(err, "cannot login")
}
// Do something with the FTP conn
if err := c.Quit(); err != nil {
log.Fatal(err)
}
}
Somehow, I'm unable to connect to the FTP server executing this code, it results in the following output:
EOF cannot connect
I tried connect to the same FTP server using FileZilla and it works fine, im able to connect to the server with success.
Any ideias on how to fix this or further debug the issue? Thank you

Answer 1

The port 22 is typically SSH/SFTP, not FTP. Note that FileZilla supports both FTP and SFTP. So chances are that you are actually connecting with SFTP using FileZilla. Those two protocols are completely different and incompatible.
There seems to be an "sftp" package for Go:
https://pkg.go.dev/github.com/pkg/sftp