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Peter Eisentraut d5d91acdcc Make error hint from bind() failure more accurate 
The hint "Is another postmaster already running ..." should only be
printed for errors that are really about something else already using
the address.  In other cases it is misleading.  So only show that hint
if errno == EADDRINUSE.

Also, since Unix-domain sockets in the file-system namespace never
report EADDRINUSE for an existing file (they would just overwrite it),
the part of the hint saying "If not, remove socket file \"%s\" and
retry." can never happen, so remove it.  Unix-domain sockets in the
abstract namespace can report EADDRINUSE, but in that case there is no
file to remove, so the hint doesn't work there either.

Reviewed-by: Michael Paquier <michael@paquier.xyz>
Discussion: https://www.postgresql.org/message-id/flat/6dee8574-b0ad-fc49-9c8c-2edc796f0033@2ndquadrant.com
 		2020-11-25 08:33:57 +01:00
..
Makefile Split all OBJS style lines in makefiles into one-line-per-entry style. 2019-11-05 14:41:07 -08:00
README.SSL Move EDH support to common files 2018-01-23 07:11:38 -05:00
auth-scram.c Fix typo in comment 2020-09-05 11:32:20 +02:00
auth.c Fix -Wcast-function-type warnings on Windows/MinGW 2020-10-21 08:17:51 +02:00
be-fsstubs.c Update copyrights for 2020 2020-01-01 12:21:45 -05:00
be-gssapi-common.c Update copyrights for 2020 2020-01-01 12:21:45 -05:00
be-secure-common.c Update copyrights for 2020 2020-01-01 12:21:45 -05:00
be-secure-gssapi.c Replace calls of htonl()/ntohl() with pg_bswap.h for GSSAPI encryption 2020-10-15 17:03:56 +09:00
be-secure-openssl.c Message style improvements 2020-11-07 19:33:43 -03:00
be-secure.c Update copyrights for 2020 2020-01-01 12:21:45 -05:00
crypt.c Initial pgindent and pgperltidy run for v13. 2020-05-14 13:06:50 -04:00
hba.c Fix unportable use of getnameinfo() in pg_hba_file_rules view. 2020-11-02 21:11:50 -05:00
ifaddr.c Update copyrights for 2020 2020-01-01 12:21:45 -05:00
pg_hba.conf.sample gss: add missing references to hostgssenc and hostnogssenc 2020-05-25 20:19:28 -04:00
pg_ident.conf.sample Reformat the comments in pg_hba.conf and pg_ident.conf 2010-01-26 06:58:39 +00:00
pqcomm.c Make error hint from bind() failure more accurate 2020-11-25 08:33:57 +01:00
pqformat.c Update copyrights for 2020 2020-01-01 12:21:45 -05:00
pqmq.c code: replace 'master' with 'leader' where appropriate. 2020-07-08 12:58:32 -07:00
pqsignal.c Update copyrights for 2020 2020-01-01 12:21:45 -05:00

README.SSL 

src/backend/libpq/README.SSL

SSL
===

>From the servers perspective:


  Receives StartupPacket
           |
           |
 (Is SSL_NEGOTIATE_CODE?) -----------  Normal startup
           |                  No
           |
           | Yes
           |
           |
 (Server compiled with USE_SSL?) ------- Send 'N'
           |                       No        |
           |                                 |
           | Yes                         Normal startup
           |
           |
        Send 'S'
           |
           |
      Establish SSL
           |
           |
      Normal startup





>From the clients perspective (v6.6 client _with_ SSL):


      Connect
         |
         |
  Send packet with SSL_NEGOTIATE_CODE
         |
         |
  Receive single char  ------- 'S' -------- Establish SSL
         |                                       |
         | '<else>'                              |
         |                                  Normal startup
         |
         |
   Is it 'E' for error  ------------------- Retry connection
         |                  Yes             without SSL
         | No
         |
   Is it 'N' for normal ------------------- Normal startup
         |                  Yes
         |
   Fail with unknown

---------------------------------------------------------------------------

Ephemeral DH
============

Since the server static private key ($DataDir/server.key) will
normally be stored unencrypted so that the database backend can
restart automatically, it is important that we select an algorithm
that continues to provide confidentiality even if the attacker has the
server's private key.  Ephemeral DH (EDH) keys provide this and more
(Perfect Forward Secrecy aka PFS).

N.B., the static private key should still be protected to the largest
extent possible, to minimize the risk of impersonations.

Another benefit of EDH is that it allows the backend and clients to
use DSA keys.  DSA keys can only provide digital signatures, not
encryption, and are often acceptable in jurisdictions where RSA keys
are unacceptable.

The downside to EDH is that it makes it impossible to use ssldump(1)
if there's a problem establishing an SSL session.  In this case you'll
need to temporarily disable EDH (see initialize_dh()).