Обсуждение: no verification of client certificate?
8.2.3 I was hoping to not have to support client certs. I want encryption and to verify the server, but no to verify the client. Does this work and I've got the config wrong? I get ssl connections if I add in the .postgresql/postgresql.crt+key. Results seem similar to this report: http://archives.postgresql.org/pgsql-general/2006-11/msg01148.php
Ray Stell <stellr@cns.vt.edu> writes:
> I was hoping to not have to support client certs. I want
> encryption and to verify the server, but no to verify the client.
> Does this work and I've got the config wrong?
Maybe I misunderstand what you want --- doesn't leaving out the
server's root.crt file do that?
regards, tom lane
Ayuda por favor Cuando ejecuto este comando me sale una doble tupla del usuario postgres, esto me error cuando ejecuto el comando Pg_dump para realizar el respectivo backup.. radar=# select * from pg_user; usename | usesysid | usecreatedb | usesuper | usecatupd | passwd | valuntil | useconfig -----------+----------+-------------+----------+-----------+----------+- ---------+----------- postgres | 1 | t | t | t | ******** | | postgres | 1 | t | t | t | ******** | | userradar | 100 | f | f | f | ******** | | (3 rows) He intentado borrar los usuario directamente de la tabla subiendo postgres com postgres -O -P -D directorio Y corriendo estos comandos.. select * from pg_shadow; delete from pg_shadow; CREATE USER postgres WITH CREATEDB CREATEUSER PASSWORD '***' SYSID 1; CREATE USER userradar PASSWORD '***' Pero me crea los mismos tres usuarios en la tabla pg_shadow, el problema es que no he podido hacer el backup y ya no tengo espacio en la particion donde tengo montada la base
On Fri, Mar 23, 2007 at 06:01:17PM -0400, Tom Lane wrote:
> Ray Stell <stellr@cns.vt.edu> writes:
> > I was hoping to not have to support client certs. I want
> > encryption and to verify the server, but no to verify the client.
> > Does this work and I've got the config wrong?
>
> Maybe I misunderstand what you want --- doesn't leaving out the
> server's root.crt file do that?
>
It doesn't look like it to me. I hope you can steer me back.
When I first looked at the ssl doc, I didn't see any description of
installing the root ca on the client. This seemed odd. On my web client,
when I need to verify the server crt, I install the appropriate ca in
the client.
Anyway, two permutations of the various config items provided ssl
connections. One was with a client crt and the other was, as you said,
no root crt on the server datadir. The verions without the client cert
was closer to what I was after.
I describe the config here:
no root.crt in the data dir
no .postgresql/ <--- this is what made me think there was no server verification
server.crt/key in the data dir
pg_hba.conf set to hostssl
PGSSLMODE=required or prefer
connect:
--------
$ psql -h serve.vt.edu -p 5437 testdb jira
Password for user jira:
Welcome to psql 8.2.3, the PostgreSQL interactive terminal.
Type: \copyright for distribution terms
\h for help with SQL commands
\? for help with psql commands
\g or terminate with semicolon to execute query
\q to quit
SSL connection (cipher: DHE-RSA-AES256-SHA, bits: 256)
strace the above connection, it tries/fails to open the client ca :
--------------------------------------------------------------------
stat64("/home/postgresql/.postgresql/root.crt", 0xbfee27d0) = -1 ENOENT (No such file or directory)
stat64("/home/postgresql/.postgresql/root.crt", 0xbfee27d0) = -1 ENOENT (No such file or directory)
So, it looks to me like I get encryption this way, but no server verification. Hope I'm wrong.
Thanks for you help.
Ray Stell <stellr@cns.vt.edu> writes:
> On Fri, Mar 23, 2007 at 06:01:17PM -0400, Tom Lane wrote:
>> Ray Stell <stellr@cns.vt.edu> writes:
>>> I was hoping to not have to support client certs. I want
>>> encryption and to verify the server, but no to verify the client.
>>> Does this work and I've got the config wrong?
>>
>> Maybe I misunderstand what you want --- doesn't leaving out the
>> server's root.crt file do that?
> It doesn't look like it to me. I hope you can steer me back.
I looked more closely and you are right: if the server does not have
a root.crt file then it doesn't send its server cert to the client,
and so there's no way for the client to verify the cert. Whereas if
it does have root.crt then it insists on verifying the client's cert.
This seems to be a restriction of OpenSSL: sending of the server cert is
implicitly enabled by enabling checking of client certs using root.crt.
Perhaps there's a way around that, but it'll take more knowledge of
OpenSSL than I have to fix it.
Offhand your desire doesn't seem completely unreasonable, so perhaps
there is a way to get OpenSSL to do it that we don't know about.
Bruce, would you add something to the TODO list?
* Support SSL configurations in which client checks server's cert but
not vice versa.
regards, tom lane
On Sun, Mar 25, 2007 at 10:01:20PM -0400, Tom Lane wrote: > I looked more closely and you are right: if the server does not have > a root.crt file then it doesn't send its server cert to the client, > and so there's no way for the client to verify the cert. Eh? ssldump shows otherwise here with 8.2.3. Here's a connection where the server has server.key and server.crt but no root.crt, and the client has the root.crt that signed server.crt and nothing else in ~/.postgresql: 1 1 0.0338 (0.0338) C>S Handshake ClientHello 1 2 0.5179 (0.4841) S>C Handshake ServerHello 1 3 0.5179 (0.0000) S>C Handshake Certificate 1 4 0.5181 (0.0001) S>C Handshake ServerKeyExchange 1 5 0.5181 (0.0000) S>C Handshake ServerHelloDone 1 6 0.6115 (0.0934) C>S Handshake ClientKeyExchange 1 7 0.6115 (0.0000) C>S ChangeCipherSpec 1 8 0.6115 (0.0000) C>S Handshake 1 9 0.9605 (0.3489) S>C ChangeCipherSpec 1 10 0.9605 (0.0000) S>C Handshake The client is now connected with DHE-RSA-AES256-SHA. Here's a dump with the same server configuration (server.key, server.crt, no root.crt) but now the client has a different root.crt than the one that signed server.crt: 1 1 0.0335 (0.0335) C>S Handshake ClientHello 1 2 0.5626 (0.5290) S>C Handshake ServerHello 1 3 0.5626 (0.0000) S>C Handshake Certificate 1 4 0.5628 (0.0001) S>C Handshake ServerKeyExchange 1 5 0.5628 (0.0000) S>C Handshake ServerHelloDone 1 6 0.5644 (0.0016) C>S Alert fatal unknown_ca If the client has PGSSLMODE set to "require" then the connection fails at the client with "psql: SSL error: certificate verify failed" and the server logs "could not accept SSL connection: tlsv1 alert unknown ca". Did you run any tests? If so, how did you generate the server's certificate? -- Michael Fuhr
Michael Fuhr <mike@fuhr.org> writes:
> On Sun, Mar 25, 2007 at 10:01:20PM -0400, Tom Lane wrote:
>> I looked more closely and you are right: if the server does not have
>> a root.crt file then it doesn't send its server cert to the client,
>> and so there's no way for the client to verify the cert.
> Eh? ssldump shows otherwise here with 8.2.3.
Well, if it works then why is the OP complaining?
Perhaps there is some non-obvious configuration issue that accounts
for the difference between your results and his?
regards, tom lane
On Mon, Mar 26, 2007 at 12:04:21AM -0400, Tom Lane wrote: > Well, if it works then why is the OP complaining? > > Perhaps there is some non-obvious configuration issue that accounts > for the difference between your results and his? I don't see in the OP's messages that he's tried the configuration I used. He said he was using the following: > > no root.crt in the data dir > > no .postgresql/ <--- this is what made me think there was no server verification > > server.crt/key in the data dir > > pg_hba.conf set to hostssl > > PGSSLMODE=required or prefer My test configuration looks the same on the server but different on the client: Server, in $PGDATA ================== server.key server.crt (signed by some CA) no root.crt Client, in ~/.postgresql ======================== root.crt (for the CA that signed server.crt) no postgresql.key or postgresql.crt The OP did say that > > When I first looked at the ssl doc, I didn't see any description of > > installing the root ca on the client. This seemed odd. On my web client, > > when I need to verify the server crt, I install the appropriate ca in > > the client. The "SSL Support" section of the libpq documentation mentions installing root.crt on the client: http://www.postgresql.org/docs/8.2/interactive/libpq-ssl.html "If the file ~/.postgresql/root.crt is present in the user's home directory, libpq will use the certificate list stored therein to verify the server's certificate. (On Microsoft Windows the file is named %APPDATA%\postgresql\root.crt.) The SSL connection will fail if the server does not present a certificate; therefore, to use this feature the server must also have a root.crt file." The requirement that the server have a root.crt appears to be incorrect, at least in the tests I ran. Unless somebody can justify that statement I'll submit a documentation patch to correct it. -- Michael Fuhr
Thanks, I'll see if I can test that this morning. A minor suggestion, perhaps said config or perhaps a reference to the Chapter 29. libpq - C Library could be added to the section on ssl: http://www.postgresql.org/docs/8.2/interactive/ssl-tcp.html If you don't mind, how do you use ssldump to trace a psql setup? That would be very helpful to know. On Sun, Mar 25, 2007 at 11:21:25PM -0600, Michael Fuhr wrote: > On Mon, Mar 26, 2007 at 12:04:21AM -0400, Tom Lane wrote: > > Well, if it works then why is the OP complaining? > > > > Perhaps there is some non-obvious configuration issue that accounts > > for the difference between your results and his? > > I don't see in the OP's messages that he's tried the configuration > I used. He said he was using the following: > > > > no root.crt in the data dir > > > no .postgresql/ <--- this is what made me think there was no server verification > > > server.crt/key in the data dir > > > pg_hba.conf set to hostssl > > > PGSSLMODE=required or prefer > > My test configuration looks the same on the server but different > on the client: > > Server, in $PGDATA > ================== > server.key > server.crt (signed by some CA) > no root.crt > > Client, in ~/.postgresql > ======================== > root.crt (for the CA that signed server.crt) > no postgresql.key or postgresql.crt > > The OP did say that > > > > When I first looked at the ssl doc, I didn't see any description of > > > installing the root ca on the client. This seemed odd. On my web client, > > > when I need to verify the server crt, I install the appropriate ca in > > > the client. > > The "SSL Support" section of the libpq documentation mentions > installing root.crt on the client: > > http://www.postgresql.org/docs/8.2/interactive/libpq-ssl.html > > "If the file ~/.postgresql/root.crt is present in the user's home > directory, libpq will use the certificate list stored therein to > verify the server's certificate. (On Microsoft Windows the file is > named %APPDATA%\postgresql\root.crt.) The SSL connection will fail > if the server does not present a certificate; therefore, to use > this feature the server must also have a root.crt file." > > The requirement that the server have a root.crt appears to be > incorrect, at least in the tests I ran. Unless somebody can justify > that statement I'll submit a documentation patch to correct it. > > -- > Michael Fuhr
On Mon, Mar 26, 2007 at 12:04:21AM -0400, Tom Lane wrote: > Michael Fuhr <mike@fuhr.org> writes: > > On Sun, Mar 25, 2007 at 10:01:20PM -0400, Tom Lane wrote: > >> I looked more closely and you are right: if the server does not have > >> a root.crt file then it doesn't send its server cert to the client, > >> and so there's no way for the client to verify the cert. > > > Eh? ssldump shows otherwise here with 8.2.3. > > Well, if it works then why is the OP complaining? Two reasons: 1. I was following: http://www.postgresql.org/docs/8.2/interactive/ssl-tcp.html I did not know this page existed: http://www.postgresql.org/docs/8.2/interactive/libpq-ssl.html Connecting the two pages would have helped me. 2. I probably made a mistake trying the various combinations. Knowing how Michael traced the connection with ssldump would be VERY helpful. Trying to put it together from strace is much harder and I probably made multiple mistakes. I was on a fishing expedition at best as I didn't know how it went together.
On Mon, Mar 26, 2007 at 09:03:53AM -0400, Ray Stell wrote: > If you don't mind, how do you use ssldump to trace a psql setup? I usually capture the connection to a file with tcpdump and then use ssldump to read the file. Sometimes I use wireshark (formerly ethereal) but it's a bit heavyweight for most of my needs. As for how to interpret what ssldump shows, I'd recommend reading Eric Rescorla's _SSL and TLS_. Rescorla wrote ssldump and used it for many of the book's diagrams; he's also the author or co-author of several of the relevant RFCs (e.g., RFC 4346 The Transport Layer Security (TLS) Protocol Version 1.1). -- Michael Fuhr
On Mon, Mar 26, 2007 at 09:35:33AM -0400, Ray Stell wrote: > Knowing how Michael traced the connection with ssldump would be > VERY helpful. The simple way is to run ssldump in one shell while running psql in another: ssldump -q port 5482 # my 8.2.3 db listens on port 5482 If I want to do more analysis I usually save the connection with tcpdump first: tcpdump -s0 -w dumpfile port 5482 The -s0 option is important: it tells tcpdump to capture the entire packet. When I'm done with psql I stop tcpdump and run ssldump over the dumpfile: ssldump -r dumpfile -q -- Michael Fuhr