Draft 139
Bitcoin versions 0.3.10 introduced an alert key system which allowed messages about critical network problems to be broadcast to all clients.
The original alert system was removed in Bitcoin Core release 0.13.0.
When an alert was in effect, the message it contained would appear in a status bar in all clients and in the "errors" field of RPC getinfo. Any script registered with the -alertnotify command-line option will be notified.
Alert message
Alerts were broadcast using the same TCP relay system as block and tx messages. They were not encoded in a special transaction. Unlike block and tx relaying, alerts were sent at the start of every new connection for as long as the alert was in effect. This ensured that everyone received the alert.
Alerts contained this information:
- How long to relay the alert.
- How long to consider the alert valid.
- An alert ID number.
- A list of alerts that should be canceled upon receipt of this alert.
- Exactly which versions of Bitcoin are affected by the alert. Unaffected versions still relay the alert for the benefit of older versions.
- Alert priority.
- The alert text.
Only alerts that are signed by a specific ECDSA public key were considered valid, but the private key was made public after the alert system was retired.
Safe mode
Until version 0.3.20, Bitcoin went into safe mode when a valid alert was received. In safe mode, all RPC commands that send BTC or get info about received BTC return an error.
History
The alert system was implemented by Satoshi Nakamoto after the value overflow incident on August 15, 2010.
List of published alerts prior to Alert Key removal
| ID | Sent date | Expires (UTC) | Versions | Priority | Message |
|---|---|---|---|---|---|
| 1010 | Feb 18, 2012 | Feb 21 02:47:15 | All | 100 | See bitcoin.org/feb20 if you have trouble connecting after 20 February |
| 1011 | Mar 16, 2012 | cancelled May 15, 2012 | 0.5 - 0.5.3 | 5000 | URGENT: security fix for Bitcoin-Qt on Windows: http://bitcoin.org/critfix |
| 1012 | Mar 16, 2012 | cancelled May 15, 2012 | 6.0 | 5000 | URGENT: security fix for Bitcoin-Qt on Windows: http://bitcoin.org/critfix |
| 1013 | Mar 16, 2012 | cancelled May 15, 2012 | 5.99 | 5000 | URGENT: security fix for Bitcoin-Qt on Windows: http://bitcoin.org/critfix |
| 1015 | May 15, 2012 | May 16, 2013 | 0.1 - 0.4.5 | 5000 | URGENT: upgrade required, see http://bitcoin.org/dos for details |
| 1016 | May 15, 2012 | May 16, 2013 | 0.4.99 - 0.5.4 | 5000 | URGENT: upgrade required, see http://bitcoin.org/dos for details |
| 1020 | May 15, 2012 | May 16, 2013 | 0.6.0 | 5000 | URGENT: upgrade required, see http://bitcoin.org/dos for details |
| 1032 | March 12, 2013 | March 13, 2013 | 0.8.0 | 5000 | URGENT: chain fork, stop mining on version 0.8 |
| 1033 | March 19, 2013 | March 20, 2013 | 0.1 - 0.7.2 | 10 | See http://bitcoin.org/may15.html for an important message |
| 1034 | May 9, 2013 | June 8, 2013 | 0.1 - 0.7.2 | 10 | Action required: see http://bitcoin.org/may15.html for more information |
| 1040 | April 11, 2014 | cancelled | 0.9.0 | 5000 | URGENT: Upgrade required: see https://www.bitcoin.org/heartbleed/ |
| 1041 | April 11, 2014 | April 11, 2015 | 0.9.0 | 5000 | URGENT: Upgrade required: see https://www.bitcoin.org/heartbleed |
See Also
- https://github.com/bitcoin/bitcoin/pull/7692 - The pull request where removing the alert system from Bitcoin Core was discussed
Attribution
This content is based on content sourced from https://en.bitcoin.it/wiki/Alert_system under Creative Commons Attribution 3.0. Although it may have been extensively revised and updated, we acknowledge the original authors.