tor-browser

The Tor Browser
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index.rst (2867B)


      1 .. _mozilla_projects_nss_nss_tools_sslstrength:
      2 
      3 NSS Tools sslstrength
      4 =====================
      5 
      6 `sslstrength <#sslstrength>`__
      7 ------------------------------
      8 
      9 .. container::
     10 
     11 `Summary <#summary>`__
     12 ~~~~~~~~~~~~~~~~~~~~~~
     13 
     14 .. container::
     15 
     16   A simple command-line client which connects to an SSL-server, and reports back the encryption
     17   cipher and strength used.
     18 
     19 `Synopsis <#synopsis>`__
     20 ~~~~~~~~~~~~~~~~~~~~~~~~
     21 
     22 .. container::
     23 
     24   1) sslstrength ciphers
     25   2) sslstrength hostname[:port] [ciphers=xyz] [debug] [verbose] [policy=export|domestic]
     26 
     27 `Description <#description>`__
     28 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     29 
     30 .. container::
     31 
     32   The first form simple lists out the possible ciphers. The letter in the first column of the
     33   output is used to identify the cipher preferences in the ciphers=  command.
     34   The second form attempts to connect to the named ssl host. The hostname argument must be present.
     35   However, the port number is an optional argument, and if not given, will default to the https
     36   port (443).
     37 
     38   .. rubric:: Restricting Ciphers
     39      :name: restricting_ciphers
     40 
     41   By default, sslstrength assumes that all the preferences are on, so it will use any preferences
     42   in your policy. The enabled ciphersuites will always be printed out before the connection is
     43   made. If you want to test out a particular cipher, there are two ways to affect which ciphers are
     44   available. Firstly, you can set **policy** to be either domestic or export. This restricts the
     45   available ciphers to the same set used by Communicator. In addition to this, the **ciphers**
     46   command can be used to further restrict the ciphers available. The argument to the ciphers
     47   command is a string of characters, where each single character represents a cipher. You can
     48   obtain this list of character->cipher mappings by doing 'sslstrength ciphers'. For example,
     49   **    ciphers=bfi** will turn on these cipher preferences and turn off all others.
     50 
     51   **    policy=export** or **policy=domestic** will set your policies appropriately.
     52 
     53   | **    policy** will default to domestic if not specified.
     54 
     55   .. rubric:: Step-up
     56      :name: step-up
     57 
     58   Step up is a mode where the connection starts out with 40-bit encryption, but due to a
     59   'change-cipher-spec' handshake, changes to 128-bit encryption. This is only done in 'export
     60   mode', with servers with a special certificate. You can tell if you stepped-up, because the
     61   output will says 'using export policy', and you'll find the secret key size was 128-bits.
     62 
     63 `Prerequisites <#prerequisites>`__
     64 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     65 
     66 .. container::
     67 
     68   You should have a cert7.db in the directory in which you run sslstrength.
     69 
     70 `Other <#other>`__
     71 ~~~~~~~~~~~~~~~~~~
     72 
     73 .. container::
     74 
     75   For references, here is a table of well-known SSL port numbers:
     76 
     77   ===== ===
     78   HTTPS 443
     79   IMAPS 993
     80   NNTPS 563
     81   ===== ===