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I configured a TOR bridge on my Ubuntu 20.04 VPS:

/etc/tor/torrc:

ORPort 443
Nickname Bridge9812
ContactInfo [email protected]
BridgeRelay 1
PublishServerDescriptor 0
ServerTransportPlugin obfs4 exec /usr/bin/obfs4proxy -enableLogging -unsafeLogging -logLevel DEBUG
ServerTransportListenAddr obfs4 0.0.0.0:37198
ExtORPort auto
Log notice file /var/log/tor/notices.log
Log debug file /var/log/tor/debug.log

I took the Bridge peer address from /var/lib/tor/pt_state/obfs4_bridgeline.txt and fingerprint from /var/lib/tor/fingerprint

obfs4 75.34.243.100:443 B99D5FB2E1D669FA356A1A69A9C07CA6B6865FCE cert=s0G3BkvOB2L0g76aSJs1sMt3TMeH18Hmb/hX85ujtJJJAystAD5hdK3e4a9HbE3GGMlvEA iat-mode=0

However, from my browser the bridge is not reachable, the logs say:

2023-02-12 21:29:35.595 [NOTICE] New control connection opened from 127.0.0.1.
2023-02-12 21:29:35.595 [NOTICE] New control connection opened from 127.0.0.1.
2023-02-12 21:29:35.601 [NOTICE] DisableNetwork is set. Tor will not make or accept non-control network connections. Shutting down all existing connections.
2023-02-12 21:29:43.628 [NOTICE] Opening Socks listener on 127.0.0.1:9150
2023-02-12 21:29:43.629 [NOTICE] Opened Socks listener connection (ready) on 127.0.0.1:9150
2023-02-12 21:29:44.554 [NOTICE] Bootstrapped 1% (conn_pt): Connecting to pluggable transport
2023-02-12 21:29:44.555 [NOTICE] Bootstrapped 2% (conn_done_pt): Connected to pluggable transport
2023-02-12 21:29:44.625 [WARN] Proxy Client: unable to connect OR connection (handshaking (proxy)) with 75.34.243.100:443 ID=<none> RSA_ID=B99D5FB2E1D669FA356A1A69A9C07CA6B6865FCE ("general SOCKS server failure")
2023-02-12 21:29:45.744 [WARN] Proxy Client: unable to connect OR connection (handshaking (proxy)) with 75.34.243.100:443 ID=<none> RSA_ID=B99D5FB2E1D669FA356A1A69A9C07CA6B6865FCE ("general SOCKS server failure")
2023-02-12 21:29:47.627 [WARN] Proxy Client: unable to connect OR connection (handshaking (proxy)) with 75.34.243.100:443 ID=<none> RSA_ID=B99D5FB2E1D669FA356A1A69A9C07CA6B6865FCE ("general SOCKS server failure")

I don't see any messages in /var/lib/tor/pt_state/obfs4proxy.log, /var/log/tor/notices.log, or /var/log/tor/debug.log.

The bridge is accessible via telnet 75.34.243.100 443 from my laptop where I have the TOR browser installed. The TOR relay check tool says it is reachable. How can I troubleshoot that handshaking proxy error?

Version information:

tor browser: 12.0.2
tor bridge on ubuntu: 0.4.7.13

any help much appreciated!

Update: after some investigation I found the following message in obfs4proxy.log:

==> /var/lib/tor/pt_state/obfs4proxy.log <==
2023/02/14 10:59:33 [WARN]: obfs4([scrubbed]:11423) - handshake failed: handshake: Failed to find M_[C,S]
2023/02/14 11:00:35 [WARN]: obfs4([scrubbed]:11395) - handshake failed: handshake: Failed to find M_[C,S]
2023/02/14 11:01:14 [WARN]: obfs4([scrubbed]:11405) - handshake failed: handshake: Failed to find M_[C,S]
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  • I'm not sure what this issue is, but your tor version is fairly old (0.4.2.7 was released 2020-03-18).
    – Steve
    Feb 13, 2023 at 20:58
  • I installed latest tor-0.4.7.13, the same issue. How may i check that hoster blocks tor?
    – swserg
    Feb 13, 2023 at 23:37
  • i found some handshake error, anybody faced this?
    – swserg
    Feb 14, 2023 at 13:31

1 Answer 1

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You have two problems here:

  1. You have relatively old software. Use an official Tor's APT or just download it and install, latest stable versions will be just fine
  2. Some kind of SSL censorship/mismatch is happening on the way for sure, but try to use not the 443 but an obfs4 port instead, and for your ORPort use 443 on a separate IP - map them by binding not to 0.0.0.0 but to the two different IP addresses respectively
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