I have the following docker-compose app:

version: '3.2'

    build: ./tor
      - "socket:/var/run/tor"
    build: ./app
      - tor
      - "socket:/var/run/tor"


My torrc file:

Log notice stdout
SOCKSPort 9050
ControlSocket /var/run/tor/control
ControlSocketsGroupWritable 1

I use this setup in my Dockerfile to pre-configure everything for the socket:

RUN adduser \
    --quiet \
    --system \
    --disabled-password \
    --home /var/lib/tor \
    --no-create-home \
    --shell /bin/bash \
    --group \
RUN mkdir -p /var/run/tor
RUN find /var/run/tor \( \( ! -user debian-tor \) -o \( ! -group debian-tor \) \) -print0 | xargs -0 --no-run-if-empty chown debian-tor:debian-tor
RUN find /var/run/tor -type d -print0 | xargs -0 --no-run-if-empty chmod 02750
RUN find /var/run/tor -type f -print0 | xargs -0 --no-run-if-empty chmod 00600
USER debian-tor

I try to check the connection with the following command:

$ curl -v --unix-socket /var/run/tor/control https://check.torproject.org

I'm getting the following error even inside the Tor container itself if I try with a http site:

* Rebuilt URL to: http://check.torproject.org/
*   Trying /var/run/tor/control...
* Connected to check.torproject.org (/var/run/tor/control) port 80 (#0)
> GET / HTTP/1.1
> Host: check.torproject.org
> User-Agent: curl/7.52.1
> Accept: */*
514 Authentication required.
* Curl_http_done: called premature == 0
* Connection #0 to host check.torproject.org left intact

Or with a https site:

$ curl --insecure -vvvv --unix-socket /var/run/tor/control https://check.torproject.org
* Rebuilt URL to: https://check.torproject.org/
*   Trying /var/run/tor/control...
* Connected to check.torproject.org (/var/run/tor/control) port 443 (#0)
* ALPN, offering h2
* ALPN, offering http/1.1
* Cipher selection: ALL:!EXPORT:!EXPORT40:!EXPORT56:!aNULL:!LOW:!RC4:@STRENGTH
* successfully set certificate verify locations:
*   CAfile: /etc/ssl/certs/ca-certificates.crt
  CApath: /etc/ssl/certs
* TLSv1.2 (OUT), TLS header, Certificate Status (22):
* TLSv1.2 (OUT), TLS handshake, Client hello (1):
* error:140770FC:SSL routines:SSL23_GET_SERVER_HELLO:unknown protocol
* Curl_http_done: called premature == 1
* stopped the pause stream!
* Closing connection 0
curl: (35) error:140770FC:SSL routines:SSL23_GET_SERVER_HELLO:unknown protocol

But everything works when I query with:

$ curl --socks5 https://check.torproject.org

Why the unix socket solution not working?

1 Answer 1


First of all, ControlPort isn't used to send data over Tor, it's used to get information and set configuration options from the Tor client.

If you want to connect over a UNIX socket and connect over it, you want to set a SOCKSPort. For example:

SocksPort unix:/var/lib/tor/socks.sock

However, curl's --unix-socket assumes some kind of HTTP proxy and it doesn't seem to speak SOCKS. As seen below:

create a listener

$ python
>>> import socket
>>> sock = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
>>> sock.bind('./uds')
>>> sock.listen(1)
>>> connection, client_address = sock.accept()

then make a request

$ curl --unix-socket ./uds http://google.com

and see what it sent

>>> req = connection.recv(4096)
>>> req
'GET / HTTP/1.1\r\nHost: google.com\r\nUser-Agent: curl/7.52.1\r\nAccept: */*\r\n\r\n'

It sends a straight HTTP request, and makes no attempt to negotiate SOCKS, so curl's --unix-socket option won't be suitable for use with Tor in that way.

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