我在使用 freetds 从 Red Hat 机器连接到我的 Microsoft SQL Server 2005 时遇到了问题。我的最终目标是能够使用 php 的 PDO 进行连接，但在使用“tsql”进行测试时似乎无法连接。
我不认为这是一个防火墙问题，因为我可以顺利地通过 telnet 进入防火墙。
$ telnet <ip> 1433
Trying <ip>...
Connected to <ip>.
Escape character is '^]'.
运行以下命令将产生以下结果：
$ TDSVER=7.1 tsql -H <ip> -p 1433 -U <user> -P <pass>
locale is "en_US.UTF-8"
locale charset is "UTF-8"
using default charset "UTF-8"
5Error 20003 (severity 6):
Adaptive Server connection timed out
OS error 115, "Operation now in progress"
Error 20002 (severity 9):
Adaptive Server connection failed
There was a problem connecting to the server
我相信这是正确的配置，因为如果我在本地 Debian 机器上运行相同的命令，它似乎会成功。
$ TDSVER=7.1 tsql -H <ip> -p 1433 -U <user> -P <pass>
locale is "en_US.UTF-8"
locale charset is "UTF-8"
using default charset "UTF-8"
1>
我尝试连接设置“TDSVER=7.0”、“TDSVER=7.2”、“TDSVER=8.0”，但它们都不起作用。
以下是错误日志：
09:50:45.013838 17363 (log.c:196):Starting log file for FreeTDS 0.91
on 2014-05-09 09:50:45 with debug flags 0xffff.
09:50:45.014138 17363 (iconv.c:330):tds_iconv_open(0x18e63e0, UTF-8)
09:50:45.014334 17363 (iconv.c:187):local name for ISO-8859-1 is ISO-8859-1
09:50:45.014349 17363 (iconv.c:187):local name for UTF-8 is UTF-8
09:50:45.014354 17363 (iconv.c:187):local name for UCS-2LE is UCS-2LE
09:50:45.014358 17363 (iconv.c:187):local name for UCS-2BE is UCS-2BE
09:50:45.014362 17363 (iconv.c:349):setting up conversions for client charset "UTF-8"
09:50:45.014366 17363 (iconv.c:351):preparing iconv for "UTF-8" <-> "UCS-2LE" conversion
09:50:45.014376 17363 (iconv.c:391):preparing iconv for "ISO-8859-1" <-> "UCS-2LE" conversion
09:50:45.014389 17363 (iconv.c:394):tds_iconv_open: done
09:50:45.014400 17363 (net.c:205):Connecting to <ip> port 1433 (TDS version 7.1)
09:50:45.014577 17363 (net.c:270):tds_open_socket: connect(2) returned "Operation now in progress"
09:50:45.019725 17363 (net.c:310):tds_open_socket() succeeded
09:50:45.019751 17363 (util.c:156):Changed query state from DEAD to IDLE
09:50:45.019767 17363 (net.c:741):Sending packet
<censored>
09:50:50.021625 17363 (util.c:331):tdserror(0x18e6140, 0x18e63e0, 20003, 115)
09:50:50.021743 17363 (util.c:361):tdserror: client library returned TDS_INT_CANCEL(2)
09:50:50.021751 17363 (util.c:384):tdserror: returning TDS_INT_CANCEL(2)
09:50:50.021796 17363 (util.c:156):Changed query state from IDLE to DEAD
09:50:50.021808 17363 (login.c:466):login packet rejected
09:50:50.021813 17363 (util.c:331):tdserror(0x18e6140, 0x18e63e0, 20002, 0)
09:50:50.021823 17363 (util.c:361):tdserror: client library returned TDS_INT_CANCEL(2)
09:50:50.021828 17363 (util.c:384):tdserror: returning TDS_INT_CANCEL(2)
09:50:50.021833 17363 (mem.c:615):tds_free_all_results()
这是我的 /etc/freetds.conf 文件
# $Id: freetds.conf,v 1.12 2007/12/25 06:02:36 jklowden Exp $
#
# This file is installed by FreeTDS if no file by the same
# name is found in the installation directory.
#
# For information about the layout of this file and its settings,
# see the freetds.conf manpage "man freetds.conf".
# Global settings are overridden by those in a database
# server specific section
[global]
# TDS protocol version
tds version = 7.1
# Whether to write a TDSDUMP file for diagnostic purposes
# (setting this to /tmp is insecure on a multi-user system)
dump file = /tmp/freetds.log
debug flags = 0xffff
# Command and connection timeouts
timeout = 5
#connect timeout = 10
# If you get out-of-memory errors, it may mean that your client
# is trying to allocate a huge buffer for a TEXT field.
# Try setting 'text size' to a more reasonable limit
text size = 64512
# A typical Sybase server
#[egServer50]
# host = symachine.domain.com
# port = 5000
# tds version = 5.0
# A typical Microsoft server
#[egServer70]
# host = ntmachine.domain.com
# port = 1433
# tds version = 7.0
# Define a connection to the MSSQL server.
[mssql]
host = <ip>
port = 1433
tds version = 7.1
编辑：
我在免费的 TDS 文档中看到我应该使用 7.2，但这似乎不起作用。
http://www.freetds.org/userguide/choosingtdsprotocol.htm
编辑2：
我也尝试过 sqsh
sqsh -D <dbname> -S <ipaddy> -U <user> -P <password>
sqsh-2.5 Copyright (C) 1995-2001 Scott C. Gray
Portions Copyright (C) 2004-2014 Michael Peppler and Martin Wesdorp
This is free software with ABSOLUTELY NO WARRANTY
For more information type '\warranty'
Open Client Message
Layer 0, Origin 0, Severity 78, Number 35
Adaptive Server connection timed out
答案1
该问题是防火墙问题。
据我所知，当我这样做的时候
telnet <ip> 1433
Trying <ip>...
Connected to <ip>.
它实际上没有连接到服务器。如果我等一分钟它就会断开连接。我在机器上安装了 Wireshark，并注意到服务器没有对 telnet 请求发送响应。
另一个证明是防火墙问题的证据是，我可以从另一台机器连接到数据库，但不能从服务器连接到数据库。所以我创建了一个 ssh 隧道来表明问题不在于应用程序的配置方式，而在于网络。
ssh -L 1433:theServerGivingMeIssues:1433 SQLserver
我可以在没有隧道的情况下连接到 SQL 服务器，但是如果使用隧道则无法连接。