Shadowsocks-libev: UDP forwarding does not work

[bsdhsr]

shadowsocks-libev 1.4.6 running on Debian wheezy.

TCP works OK.

Use case is connecting to a OpenVPN server (with proto udp) using the socks-proxy option, through shadowsocks.

[ovpn@freebsd] -----[socks5]----> [ss-local@debian] ----[internet]-----> [ss-server@debian] ----> [dst ovpn]

NOTE!!!: One unusual (I guess) aspect of this setup is that shadowsocks ss-local is not running locally on the machine that I'm running OpenVPN from; this is simply due to the shadowsocks-libev FreeBSD port segfaulting as soon as I throw any UDP traffic it's way (the port is older at 1.4.0, perhaps it's a bug from that version)

openvpn stdout reads (ips redacted):
Attempting to establish TCP connection with AF_INET:10080 [nonblock]
TCP connection established with [AF_INET]ss-local:10080
UDPv4 link local: [undef]
UDPv4 link remote: [AF_INET]ovpn-server:ovpn-port

Meanwhile, at ss-local, I see:
"INFO: [udp] assc request accepted"
"INFO: [udp] server receive a packet"
"INFO: [udp] cache missed: ovpn-server:ovpn-port <-> freebsd-ip:$someport

At the same time, I am running tcpdump, and see no attempts whatsoever to contact the remote ss-server at all.

Therefore, the forwarding doesn't work.

This seems to be the same issue as #105.

Any ideas?

[madeye]

Could you also post the log of ss-server?

[bsdhsr]

Remember, ss-local never attempts to contact ss-server at all when using UDP -100% sure.

This is why I included no logs from it (and a small ascii description of the path the packeta travel, in the offchance that I misunderstood how to interconnect the parts).

Let me know if there is something that I am missing.

Could you post a working configuration for all parts (ss-*), the version running, and how they interconnect?

[bsdhsr]

FYI, I have also now tried to run OpenVPN in the Debian VM, and the same situation occurs (except that the IP in the "cache missed" message is now debian's IP).

[madeye]

To me, it seems all your UDP traffic are filtered by firewall or something similar. Could you check that the UDP packets are able to reach your server's port used by shadowsocks?

[bsdhsr]

You are correct. Since I saw OpenVPN connecting to shadowsocks using TCP, I never checked UDP traffic.

It's working now, thanks for the tip.

[ovizii]

Just a quick follow-up:

Say I am using shadowsocks on my mobile phone and enable UDP forwarding while my shadowsocks-libev is installed on my NAS functioning as my proxy server, which ports would I need to enable on my firewall for UDP forwarding to work?

[Kein]

Ah yes, immortal classic - an issue from a decade ago that is relevant to my issue but has no resolution.

[Demigod-Moui]

Ah yes, immortal classic - an issue from a decade ago that is relevant to my issue but has no resolution.

I encountered the same problem, one month later