From f5020684dbabe60dcfb430660455c3f9851a0e63 Mon Sep 17 00:00:00 2001
From: Magnus Hagander <magnus@hagander.net>
Date: Fri, 24 Oct 2008 11:48:29 +0000
Subject: [PATCH] Remove large parts of the old SSL readme, that consisted of a
couple of copy/paste:d emails. Much of the contents had already been migrated
into the main documentation, some was out of date and some just plain wrong.
Keep the "protocol-flowchart" which can still be useful.
---
src/backend/libpq/README.SSL | 430 +----------------------------------
1 file changed, 1 insertion(+), 429 deletions(-)
diff --git a/src/backend/libpq/README.SSL b/src/backend/libpq/README.SSL
index 1897ab01ae6..8fae93d4cfc 100644
--- a/src/backend/libpq/README.SSL
+++ b/src/backend/libpq/README.SSL
@@ -1,4 +1,4 @@
-$PostgreSQL: pgsql/src/backend/libpq/README.SSL,v 1.6 2008/03/21 13:23:28 momjian Exp $
+$PostgreSQL: pgsql/src/backend/libpq/README.SSL,v 1.7 2008/10/24 11:48:29 mha Exp $
SSL
===
@@ -58,431 +58,3 @@ SSL
Fail with unknown
---------------------------------------------------------------------------
-
-
- COMMENTS FROM BEAR GILES
-
-On a related note, I had mentioned this before but it's a subtle point
-and I'm sure that it's slipped everyone's mind...
-
- - if you need to have confidence in the identity of the database
-server, e.g., you're storing sensitive information and you absolutely
-must prevent any "man in the middle" attacks, use the SSL code I
-provided with server-side certs. To many users, the key issue is not
-whether the data is encrypted, it's whether the other party can be
-trusted to be who they claim to be.
-
-- if you just need confidentiality, but you don't need to verify the
-identity of the database server (e.g., because you trust the IP address,
-but worry about packet sniffers), SSH tunnels are much easier to set up
-and maintain than the embedded SSL code. You can set up the database
-server so it doesn't require a certificate (hell, you can hard code a
-fallback certificate into the server!), *but that violates the common
-practice of SSL-enabled servers.* I cannot overemphasize this - every
-other SSL-enabled server requires a certificate, and most provide
-installation scripts to create a "snake oil" temporary certificate. I
-can't think of any server (apache+mod_ssl, courier-imap, postfix(+tls),
-etc.) that uses anonymous servers.
-
-- if you don't need confidentiality, e.g., you're on a trusted network
-segment, then use direct access to the server port.
-
----------------------------------------------------------------------------
-
- EMAIL ABOUT DOCUMENTATION
-
-From: Bear Giles <bgiles@coyotesong.com>
-Subject: [HACKERS] 2nd cut at SSL documentation
-To: pgsql-hackers@postgresql.org
-Date: Tue, 21 May 2002 14:27:00 -0600 (MDT)
-
-A second cut at SSL documentation....
-
-
-
-SSL Support in PostgreSQL
-=========================
-
-Who needs it?
-=============
-
-The sites that require SSL fall into one (or more) of several broad
-categories.
-
-*) They have insecure networks.
-
- Examples of insecure networks are anyone in a "corporate hotel,"
- any network with 802.11b wireless access points (WAP) (in 2002,
- this protocol has many well-known security weaknesses and even
- 'gold' connections can be broken within 8 hours), or anyone
- accessing their database over the internet.
-
- These sites need a Virtual Private Network (VPN), and either
- SSH tunnels or direct SSL connections can be used.
-
-*) They are storing extremely sensitive information.
-
- An example of extremely sensitive information is logs from
- network intrusion detection systems. This information *must*
- be fully encrypted between front- and back-end since an attacker
- is presumably sniffing all traffic within the VPN, and if they
- learn that you know what they are doing they may attempt to
- cover their tracks with a quick 'rm -rf /' and 'dropdb'
-
- In the extreme case, the contents of the database itself may
- be encrypted with either the crypt package (which provides
- symmetrical encryption of the records) or the PKIX package
- (which provides public-key encryption of the records).
-
-*) They are storing information which is considered confidential
- by custom, law or regulation.
-
- This includes all records held by your doctor, lawyer, accountant,
- etc. In these cases, the motivation for using encryption is not
- a conscious evaulation of risk, but the fear of liability for
- 'failure to perform due diligence' if encryption is available but
- unused and an attacker gains unauthorized access to the harm of
- others.
-
-*) They have 'road warriors.'
-
- This includes all sites where people need to have direct access
- to the database (not through a proxy such as a secure web page)
- from changing remote addresses. Client certificates provide a
- clean way to grant this access without opening up the database
- to the world.
-
-Who does not need it?
----------------------
-
-It's at least as important to know who does not need SSL as it
-is to know who does. Sites that do not need SSL fall into several
-broad categories.
-
-*) Access is limited to the Unix socket.
-
-*) Access is limited to a physically secure network.
-
- "Physically secure" networks are common in the clusters and
- colocation sites - all database traffic is restricted to dedicated
- NIC cards and hubs, and all servers and cabling are maintained in
- locked cabinets.
-
-
-Using SSH/OpenSSH as a Virtual Private Network (VPN)
-====================================================
-
-SSH and OpenSSH can be used to construct a Virtual Private Network
-(VPN) to provide confidentiality of PostgreSQL communications.
-These tunnels are widely available and fairly well understood, but
-do not provide any application-level authentication information.
-
-To set up a SSH/OpenSSH tunnel, a shell account for each
-user should be set up on the database server. It is acceptable
-for the shell program to be bogus (e.g., /bin/false), if the
-tunnel is set up in to avoid launching a remote shell.
-
-On each client system the ~/.ssh/config file should contain
-an additional line similiar to
-
- LocalForward 5555 psql.example.com:5432
-
-(replacing psql.example.com with the name of your database server).
-By putting this line in the configuration file, instead of specifying
-it on the command line, the tunnel will be created whenever a
-connection is made to the remote system.
-
-The psql(1) client (or any client) should be wrapped with a script
-that establishes an SSH tunnel when the program is launched:
-
- #!/bin/sh
- HOST=psql.example.com
- IDENTITY=~/.ssh/identity.psql
- /usr/bin/ssh -1 -i $IDENTITY -n $HOST 'sleep 60' & \
- /usr/bin/psql -h $HOST -p 5555 $1
-
-Alternatively, the system could run a daemon that establishes and maintains
-the tunnel. This is preferrable when multiple users need to establish
-similar tunnels to the same remote site.
-
-Unfortunately, there are many potential drawbacks to SSL tunnels:
-
-*) the SSH implementation or protocol may be flawed. Serious problems
- are discovered about once every 18- to 24- months.
-
-*) the systems may be misconfigured by accident.
-
-*) the database server must provide shell accounts for all users
- needing access. This can be a chore to maintain, esp. in if
- all other user access should be denied.
-
-*) neither the front- or back-end can determine the level of
- encryption provided by the SSH tunnel - or even whether an
- SSH tunnel is in use. This prevents security-aware clients
- from refusing any connection with unacceptly weak encryption.
-
-*) neither the front- or back-end can get any authentication
- information pertaining to the SSH tunnel.
-
-Bottom line: if you just need a VPN, SSH tunnels are a good solution.
-But if you explicitly need a secure connection they're inadequate.
-
-
-Direct SSL Support
-==================
-
-Insecure Channel: ANONYMOUS DH Server
--------------------------------------
-
-"ANONYMOUS DH" is the most basic SSL implementation. It does
-not require a server certificate, but it is vulnerable to
-"man-in-the-middle" attacks.
-
-The PostgreSQL backend does not support ANONYMOUS DH sessions.
-
-
-Secure Channel: Server Authentication
--------------------------------------
-
-Server Authentication requires that the server authenticate itself
-to clients (via certificates), but clients can remain anonymous.
-This protects clients from "man-in-the-middle" attacks (where a
-bogus server either captures all data or provides bogus data),
-but does not protect the server from bad data injected by false
-clients.
-
-The community has established a set of criteria for secure
-communications:
-
-*) the server must provide a certificate identifying itself
- via its own fully qualified domain name (FDQN) in the
- certificate's Common Name (CN) field.
-
-*) the FQDN in the server certificate must resolve to the
- IP address used in the connection.
-
-*) the certificate must be valid. (The current date must be
- no earlier than the 'notBefore' date, and no later than the
- 'notAfter' date.)
-
-*) the server certificate must be signed by an issuer certificate
- known to the clients.
-
- This issuer can be a known public CA (e.g., Verisign), a locally
- generated root cert installed with the database client, or the
- self-signed server cert installed with the database client.
-
- Another approach (used by SSH and most web clients) is for the
- client to prompt the user whether to accept a new root cert when
- it is encountered for the first time. psql(1) does not currently
- support this mechanism.
-
-*) the client *should* check the issuer's Certificate Revocation
- List (CRL) to verify that the server's certificate hasn't been
- revoked for some reason, but in practice this step is often
- skipped.
-
-*) the server private key must be owned by the database process
- and not world-accessible. It is recommended that the server
- key be encrypted, but it is not required if necessary for the
- operation of the system. (Primarily to allow automatic restarts
- after the system is rebooted.)
-
-The 'mkcert.sh' script can be used to generate and install
-suitable certificates
-
-Finally, the client library can have one or more trusted root
-certificates compiled into it. This allows clients to verify
-certificates without the need for local copies. To do this,
-the source file src/interfaces/libpq/fe-ssl.c must be edited
-and the database recompiled.
-
-Secure Channel: Mutual Authentication
--------------------------------------
-
-Mutual authentication requires that servers and clients each
-authenticate to the other. This protects the server from
-false clients in addition to protecting the clients from false
-servers.
-
-The community has established a set of criteria for client
-authentication similar to the list above.
-
-*) the client must provide a certificate identifying itself.
- The certificate's Common Name (CN) field should contain the
- client's usual name.
-
-*) the client certificate must be signed by a certificate known
- to the server.
-
- If a local root cert was used to sign the server's cert, the
- client certs can be signed by the issuer.
-
-*) the certificate must be valid. (The current date must be
- no earlier than the 'notBefore' date, and no later than the
- 'notAfter' date.)
-
-*) the server *should* check the issuer's Certificate Revocation
- List (CRL) to verify that the clients's certificate hasn't been
- revoked for some reason, but in practice this step is often
- skipped.
-
-*) the client's private key must be owned by the client process
- and not world-accessible. It is recommended that the client
- key be encrypted, but because of technical reasons in the
- architecture of the client library this is not yet supported.
-
-PostgreSQL can generate client certificates via a four-step process.
-
-1. The "client.conf" file must be copied from the server. Certificates
- can be highly localizable, and this file contains information that
- will be needed later.
-
- The client.conf file is normally installed in /etc/postgresql/root.crt.
- The client should also copy the server's root.crt file to
- ~/.postgresql/root.crt.
-
-2. If the user has the OpenSSL applications installed, they can
- run pgkeygen.sh. (An equivalent compiled program will be available
- in the future.) They should provide a copy of the
- ~/.postgresql/postgresql.pem file to their DBA.
-
-3. The DBA should sign this file the OpenSSL applications:
-
- $ openssl ca -config root.conf -ss_cert ....
-
- and return the signed cert (postgresql.crt) to the user.
-
-4. The user should install this file in ~/.postgresql/postgresql.crt.
-
-The server will log every time a client certificate has been
-used, but there is not yet a mechanism provided for using client
-certificates as PostgreSQL authentication at the application level.
-
-
----------------------------(end of broadcast)---------------------------
-TIP 5: Have you checked our extensive FAQ?
-
-http://www.postgresql.org/users-lounge/docs/faq.html
-
-------------------------------------------------------------------------------
-
-Date: Tue, 21 May 2002 19:50:38 -0400
-From: Neil Conway <nconway@klamath.dyndns.org>
-To: "Bear Giles" <bgiles@coyotesong.com>
-cc: pgsql-hackers@postgresql.org
-Subject: Re: [HACKERS] 2nd cut at SSL documentation
-
-On Tue, 21 May 2002 14:27:00 -0600 (MDT)
-"Bear Giles" <bgiles@coyotesong.com> wrote:
-> A second cut at SSL documentation....
-
-I've pointed out some minor things I noticed while reading through.
-Yeah, I was bored :-)
-
-> The sites that require SSL fall into one (or more) of several broad
-> categories.
->
-> *) They have insecure networks.
->
-> Examples of insecure networks are anyone in a "corporate hotel,"
-
-What's a corporate hotel?
-
-> *) They have 'road warriors.'
-
-This section title sounds confusingly similar to the 1st item.
-Perhaps "They need to authentication clients securely" or something
-similar? The need to use client certificates does not apply only to
-"road warriors" -- I've seen situations where client-certs are used for
-clients to connecting to a server over a LAN.
-
-> *) Access is limited to the Unix socket.
-
-"the" sounds wrong, there's more than just 1 :-)
-
-> *) Access is limited to a physically secure network.
->
-> "Physically secure" networks are common in the clusters and
-> colocation sites - all database traffic is restricted to dedicated
-> NIC cards and hubs, and all servers and cabling are maintained in
-> locked cabinets.
-
-Perhaps add a note on the performance hit here?
-
-> Using SSH/OpenSSH as a Virtual Private Network (VPN)
-
-I'm unsure why you're bothering to differentiate between SSH
-and OpenSSH.
-
-> SSH and OpenSSH can be used to construct a Virtual Private Network
-> (VPN)
-
-No need to include the abbreviation for VPN here, you've explained
-the term before.
-
-> to provide confidentiality of PostgreSQL communications.
-> These tunnels are widely available and fairly well understood, but
-> do not provide any application-level authentication information.
-
-You might want to clarify what "application-level authentication
-information" means, or else leave out all discussion of drawbacks
-until later.
-
-> To set up a SSH/OpenSSH tunnel, a shell account for each
-> user should be set up on the database server. It is acceptable
-> for the shell program to be bogus (e.g., /bin/false), if the
-> tunnel is set up in to avoid launching a remote shell.
->
-> On each client system the ~/.ssh/config file should contain
-> an additional line similiar to
->
-> LocalForward 5555 psql.example.com:5432
-
-"pgsql.example.com" strikes me as a better example hostname (I always
-think that psql == DB client, postgres/postmaster/pgsql == DB server).
-
-> Unfortunately, there are many potential drawbacks to SSL tunnels:
-
-I think you mean SSH tunnels.
-
-> *) the SSH implementation or protocol may be flawed. Serious problems
-> are discovered about once every 18- to 24- months.
-
-I'd be skeptical whether this weakness if specific to SSH -- there
-can be security holes in OpenSSL, the SSL protocol, the SSL
-implementation in PostgreSQL, etc.
-
-> *) the database server must provide shell accounts for all users
-> needing access. This can be a chore to maintain, esp. in if
-
-Remove the "in".
-
-> *) neither the front- or back-end can determine the level of
-> encryption provided by the SSH tunnel - or even whether an
-> SSH tunnel is in use. This prevents security-aware clients
-> from refusing any connection with unacceptly weak encryption.
-
-Spelling error.
-
-> Finally, the client library can have one or more trusted root
-> certificates compiled into it. This allows clients to verify
-> certificates without the need for local copies. To do this,
-> the source file src/interfaces/libpq/fe-ssl.c must be edited
-> and the database recompiled.
-
-"PostgreSQL" recompiled -- database versus RDBMS can be ambiguous.
-
-> Mutual authentication requires that servers and clients each
-> authenticate to the other. This protects the server from
-> false clients in addition to protecting the clients from false
-> servers.
-
-"false" in this context?
-
-Cheers,
-
-Neil
-
---
-Neil Conway <neilconway@rogers.com>
--
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