ssh port issue:curl: (6) Couldn't resolve host '127.0.0.1:ssh'

On my Windows XP machine, I setup a WinSSHD server.

This command worked:

$ curl -T test.txt -u hdp:123 sftp://127.0.0.1:22

However, when I change the port 22 to ssh, it failed with the output:

curl: (6) Couldn't resolve host '127.0.0.1:ssh'

Why?

curl used RFC3986 for specification of URLs and there is no capacity in that standard for non-numeric port numbers:

3.2.3. Port

The port subcomponent of authority is designated by an optional port number in decimal following the host and delimited from it by a single colon (":") character.

port = *DIGIT

It allows for translation of a DNS name, so that you can use localhost rather than 127.0.0.1 for example, but not for the port identifier. It would probably be a relatively minor change to allow curl to look up services externally (such as in /etc/services) but it currently does not do that.

Alternatively, you could find a separate way to convert ssh into 22 and use that. For example, the getent services ssh command on Linux returns something like:

ssh     22/tcp

so you could use a command like (split over lines for readability but should be on a single line):

curl -T test.txt -u hdp:123 sftp://127.0.0.1:$(
    getent services ssh | awk '{gsub("/.*", "", $2); print $2}')

to achieve what you want. The command within $() runs the afore-mentioned getent program to generate the information then awk is used to extract just the 22 bit.

You could even make this a Bash function with something like:

port_of() {
    if [[ -z "$1" ]] || [[ -z "$2" ]] ; then
        echo >&2 "Args were: '$1' '$2'"
        echo >&2 "    Usage: port_of DB KEY"
        echo >&2 "       eg: port_of services ssh"
        return 1
    fi
    getent "$1" "$2" | awk '{
        gsub("/.*", "", $2)
        print $2
    }'
}

# Testing code:
#     port_of
#     port_of services
#     port_of services ssh

Then your use becomes the much simpler:

curl -T test.txt -u hdp:123 sftp://127.0.0.1:$(port_of services ssh)