Dante proxy not working on ubuntu 18.04 give negotiation timeout

Question

I used this guide https://gist.github.com/gpchelkin/c7d24a21639d1f120fb082d1801a5fe4 to configure Dante server on ubuntu 18.04 but when I want to connect from the client I get this error

curl -v -x socks5://user:pass@server:1080 http://www.google.com
* Rebuilt URL to: http://www.google.com/
*   Trying server-ip...
* TCP_NODELAY set
* SOCKS5 communication to www.google.com:80
* Unable to receive initial SOCKS5 response.
* Closing connection 0
curl: (7) Unable to receive initial SOCKS5 response.

and also in Dante logs, I get

Dec 03 09:12:56 danted[17829]: info: block(1): tcp/accept ]: client-ip.48601 server-ip.1080: negotiate timeout after 31 seconds

also, my configuration is

logoutput: syslog
user.privileged: root
user.unprivileged: nobody
internal: 0.0.0.0 port = 1080
external: ens32
socksmethod: username
clientmethod: none
user.libwrap: nobody
client pass {
        from: 0/0 to: 0/0
        log: connect disconnect error
}
socks pass {
        from: 0/0 to: 0/0
        log: connect disconnect error
}

thank for helping

Answer 1

Possibly there is a firewall blocking data between Dante and the clients, allowing the initial TCP/IP handshake to complete, but no further data to flow.

Diagnosis can be done by either enabling debug mode in Dante ("-d2") and viewing the Dante logfile, or using tcpdump(8) or wireshark(8) to watch what network packets are received and sent by Dante.