[tor-bugs] #6728 [Compass]: explain why a relay is an 'almost-fast-exit' and not a 'fast-exit'

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#6728: explain why a relay is an 'almost-fast-exit' and not a 'fast-exit'
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 Reporter:  gsathya      |          Owner:     
     Type:  enhancement  |         Status:  new
 Priority:  normal       |      Milestone:     
Component:  Compass      |        Version:     
 Keywords:               |         Parent:     
   Points:               |   Actualpoints:     
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Comment(by karsten):

 So, we need to solve two problems here: add fast exit information to
 compass.py and display that information nicely on the website.

 For extending compass.py, I could imagine adding a new flag `--display-
 fast-exit-info` that adds four new columns to the output:

  - `bw_rate_mbits` would contain the bandwidth rate in MBit/s,
  - `adv_bw_kbytes` would contain the advertised bandwidth in KB/s,
  - `exit_ports` would list relevant permitted exit ports, e.g.,
 `80/443/554`, and
  - `same_24_id` would list the relay's position in the top-N list of fast
 exits by exit probability if the relay meets the "fast exits, any network"
 requirements, or N/A if it doesn't meet those requirements.

 These four new columns would be added anywhere before the "Autonomous
 System" column, which is the only column with previously undefined length.
 Or these columns could be appended as new last columns if the maximum
 column width of "Autonomous System" can be determined from the table
 elements before writing the table header.

 For displaying the new information on the website, there could be a new
 column "Fast exit" after the "Guard" column with values "Yes", "Almost",
 and "No", that has additional information in popovers.  The popovers would
 then summarize why a relay is only in the "Almost" or "No" category by
 looking at the four new columns.

 Alternatively, we could add a new column `fast_exit` instead of the four
 columns suggested above that contains a full sentence summarizing whether
 a relay is a fast exit, e.g., "Almost.  Bandwidth rate is only 85 Mbit/s
 and exit ports only contain 80/443."  The tricky part there would be to
 display that sentence in the command-line output of `compass.py` which
 uses fixed-length columns.  That's the same problem as for determining how
 long the "Autonomous System" column is supposed to be.

 All in all, this change requires a lot of new code.  Probably more than it
 seems from a user perspective.

-- 
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/6728#comment:5>
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