Re: Getting "Unexpected EOF from the server" when trying to connect to MS SQL Server 2014

2016-04-25 13:26 GMT+01:00 Pulver, Alex <[email protected]>:
> Hi all,
>
> I am trying to connect to MS SQL 2014 Server from SLES11 host, using FreeTDS 0.95.51 version and its tsql utility. The server uses "Standard Mode" (SQL Server Authentication) and I am able to connect from Windows using SQL Server 2014 Management Studio.
> Before sending this email I've read through FreeTDS troubleshooting, FAQ, domains page, config page, archives and various SO questions - tried the recommended configurations but with no luck (details below).
>
> The command being run is:
> env TDSVER=7.0 TDSDUMP=/tmp/tdsdump.log TDSDUMPCONFIG=/tmp/tdsdumpconfig.log ./src/apps/tsql -H <host> -p <port> -U <username> -P <password> -D <database>
>

I would try with at least 7.2 version.

> The output:
> locale is "C"
> locale charset is "ANSI_X3.4-1968"
> using default charset "ISO-8859-1"
> Setting <database> as default database in login packet
> Error 20017 (severity 9):
>         Unexpected EOF from the server
> ...
>
> Tailing TDSDUMP along with the execution shows that error is happening after the login packet is sent and FreeTDS tries to process the login tokens:
> login.c:852:quietly sending TDS 7+ login packet
> token.c:327:tds_process_login_tokens()
> <<
> Error 20017 (severity 9):
>         Unexpected EOF from the server
>>>
> query.c:3772:tds_disconnect()
>
> Looking on strace seems to confirm that server disconnects after login packet is received (poll() returns positive after sendto(), but recvfrom() returns 0):
> write(5, "login.c:852:quietly sending TDS "..., 48) = 48
> ...
> poll([{fd=6, events=POLLOUT}, {fd=4, events=POLLIN}], 2, -1) = 1 ([{fd=6, revents=POLLOUT}])
> sendto(6, "\20\1\0012\0\0\0\0*\1\0\0\0\0\0p\0\20\0\0\6\203\362\370U\354\0\0\0\0\0\0"..., 306, MSG_NOSIGNAL, NULL, 0) = 306
> write(5, "token.c:327:tds_process_login_to"..., 39) = 39

This means that server rejected the login. Like user/password wrong.
Are you using Kerberos/SSPI or SQL logins?

> poll([{fd=6, events=POLLIN}, {fd=4, events=POLLIN}], 2, -1) = 1 ([{fd=6, revents=POLLIN}])
> recvfrom(6, "", 8, MSG_NOSIGNAL, NULL, NULL) = 0
> write(5, "query.c:3772:tds_disconnect() \n", 31) = 31
>
> Things I tried listed in no particular order (assuming the issue is with authentication and not network):
> * Use UTF-8 encoding

This would change if you have extra ASCII in your username/password.

> * Disable SSPI: ./configure --disable-sspi (so that trusted authentication will not be triggered)

SSPI is supported only in Windows so it's not affecting your build.

> * Compile with latest OpenSSL version we have installed: ./configure --with-openssl=/.../openssl/1.0.1/bin/openssl
> * Explicitly disable OpenSSL: ./configure --without-openssl
> * Modifying the code in ./src/tds/mem.c to disable check_ssl_hostname by setting it to 0 in both places it appears (assuming it triggers checking server's SSL certificate and fails to authenticate). Verified using debugger that *((tds)->login) object has check_ssl_hostname set to 0
> * Modifying the code in ./src/tds/tls.c to change location of certificates pointed by ca_directory[] to a directory I know we have updated internal certificates
>

No, the check is done by FreeTDS, in this case the server is disconnecting.

> Things I still need to check with MS SQL Server admins:
> * Try to see if they can give me access to server-side log for my connection attempts
> * Check if server requires two-way authentication for SQL Server Authentication - doesn't seem like it, but I will check
>
> If someone has any other ideas as to why the connection drops, or other things I can do to investigate further, I would really appreciate that!
>

You could try increasing the log level (see "debug flags" in
http://www.freetds.org/userguide/freetdsconf.htm).
Also I would try the "use ntlmv2" flag (same page above).

> Thanks!
> Alex

Frediano