Broken OBFS4 / Snowflake / Meek bridges

[radio24]

Sporadically, there are problems with using bridges. Due to changing developments, it can be challenging to track down the reason for broken functionality. These notes should help to track down possible problems.

Problems with a fresh TorBox image

• A wrong system time (UTC) breaks the bridge functionality. To mitigate, we put a time synchronisation tool into the first-use. Update: This has improved the situation for OBFS4 bridges! ✅
• Another theory is that UpdateBridgesFromAuthority 1 breaks the bridge functionality if tor wasn't previously started up without bridges. Anyway, the default value is 0 and not 1, so it makes sense to return to the default value. Update: This has improved the situation for OBFS4 bridges! ✅

Important points to keep in mind

• OBFS4, Snowflake, and Meek don't run properly with ReachableAddresses accept *:443, accept *:80 🚨
• OBFS4, Snowflake and Meek may not work behind a captive portal (used in airports, hotels, coffee houses etc.) because the configuration prevents a connection to bridge relays/servers. 🚨
• Snowflake and Meek run only with local DNS resolution! 🚨
• As with OBFS4, Snowflake will work with multiple bridge lines, but is only using the first of these lines. 🚨

Interpretation of OBFS4 error messages
-general SOCKS server failure

1. Most probably, this is an indication of a wrong system time. Use date to manually set the exact UTC time. To fix it, use entry 15 in the Update & Maintenance Sub-menu.
2. It could also be an obfs4proxy compatibility issue, which happens with bridges that are not up-to-date. For more information, see here and here. Solution: add more OBFS4 bridge lines or change to Snowflake.

Interpretation of Snowflake error messages
-snowflake-client": broker failure dial tcp:: Most probably local clearnet DNS resolution doesn't work.