MySQL5.1之前general log不能在运行时启用或禁用，有时想捕捉SQL来查找问题就很麻烦，偶然间发现一个很不错的小工具：mysqlsniffer，可以用来捕捉SQL语句，使用帮助如下：

mysqlsniffer --help
mysqlsniffer v1.2 - Watch MySQL traffic on a TCP/IP network

Usage: mysqlsniffer [OPTIONS] INTERFACE

OPTIONS:
--port N Listen for MySQL on port number N (default 3306)
--verbose Show extra packet information
--tcp-ctrl Show TCP control packets (SYN, FIN, RST, ACK)
--net-hdrs Show major IP and TCP header values
--no-mysql-hdrs Do not show MySQL header (packet ID and length)
--state Show state
--v40 MySQL server is version 4.0
--dump Dump all packets in hex
--help Print this

Original source code and more information at:

INTERFACE是指网卡号，如eth0,eth2,lo等。

当然也有人直接tcpdump来捕捉的，方法如下：

tcpdump -i eth2 -s 0 -l -w - dst port 3306 | strings | perl -e
while(<>) { chomp; next if /^[^ ]+[ ]*$/;
if(/^(SELECT|UPDATE|DELETE|INSERT|SET|COMMIT|ROLLBACK|CREATE|DROP|ALTER)/i) {
if (defined $q) { print "$qn"; }
$q=$_;
} else {
$_ =~ s/^[ t]+//; $q.=" $_";
}
}
mysqlsniffer is a tcpdump clone specifically for dumping/sniffing/watching MySQL network protocol traffic over TCP/IP networks. mysqlsniffer is coded in C using the pcap library and works with MySQL version 4.0 and newer. mysqlsniffer is the only MySQL-specific network sniffer.

mk-query-digest also understands the MySQL protocol. It’s not a sniffer, though. It reads packet dumps from tcpdump like a slowlog. If you want to analyze queries from the wire (i.e. from network traffic), mk-query-digest is what you want.

For more information about the MySQL protocol read MySQL Internals ClientServer Protocol.

1、软件包

2、编译安装  mysqlsniffer]# gcc -O2 -lpcap -o mysqlsniffer mysqlsniffer.c packet_handlers.c misc.c

如果出现如下提示

请安装libpcap-devel 包，再重新用gcc来编译

mysqlsniffer.c:26:18: 错误：pcap.h：没有那个文件或目录

[root@real1 mysqlsniffer]# ./mysqlsniffer –help

mysqlsniffer v1.2 – Watch MySQL traffic on a TCP/IP network

Usage: mysqlsniffer [OPTIONS] INTERFACE

OPTIONS:

–port N        Listen for MySQL on port number N (default 3306)  ##指定端口

–verbose       Show extra packet information                                       ## 显示包的扩展信息

–tcp-ctrl      Show TCP control packets (SYN, FIN, RST, ACK)     ## 显示tcp包的状态

–net-hdrs      Show major IP and TCP header values                       ##显示ip和TCP的头信息

–no-mysql-hdrs Do not show MySQL header (packet ID and length)   ##不显示ip和TCP的头信息

–state         Show state                                        ## 显示状态

–v40           MySQL server is version 4.0   ##如果MySQL服务器版本是4.0 加上此参数

–dump          Dump all packets in hex   ##把输入dump成hex文件格式

–help          Print this

Original source code and more information at:

示例

./mysqlsniffer eth0 –port 3306 –tcp-ctrl –no-mysql-hdrs

server > 127.0.0.1.24266: Waiting for server to finish response… ::DUMP:: 00 89 b0 f6 J 02 01 00 00 00 aa 00 00 00 f8 7 ‘ 14 10 00 1d b6 c0 00 00 00 00 00 05 00 00 1a 00 00 00 @ 00 00 01 00 00 00 00 00 00 00 00 06 03 s t d 04 1c 00 1c 00 1c 00 w e b d b 00 U P D A T E   z y a d s _ s t a t s     S E T   v i e w s   =   v i e w s   +   6 0   W H E R E   d a y   =   ‘ 2 0 0 9 – 1 1 – 0 8 ‘     A N D   z o n e i d   =   ‘ 3 2 5 ‘     A N D   a d s i d   =   ‘ 1 8 2 ‘ ::DUMP::

127.0.0.1.24266 > server: ACK

127.0.0.1.37968 > server: SYN

server > 127.0.0.1.37968: SYN ACK

127.0.0.1.37968 > server: ACK

server > 127.0.0.1.37968: Handshake

127.0.0.1.37968 > server: ACK

127.0.0.1.37968 > server: Handshake (new auth)

server > 127.0.0.1.37968: ACK

server > 127.0.0.1.37968: OK

127.0.0.1.37968 > server: COM_INIT_DB: webdb

server > 127.0.0.1.37968: OK

127.0.0.1.37968 > server: COM_QUERY: SET NAMES ‘gbk’

server > 127.0.0.1.37968: OK

127.0.0.1.37968 > server: COM_QUERY: SET sql_mode=”

server > 127.0.0.1.37968: OK

127.0.0.1.37968 > server: COM_QUERY: SELECT cpmdeduction,cpcdeduction,cpadeduction,cpsdeduction,cpvdeduction,cpczlink,cpazlink,cpszlink FROM zyads_users

WHERE uid=770 AND status=2 limit 0,1

server > 127.0.0.1.37968: 8 Fields

Field: webdb.zyads_users.cpmdeduction

Field: webdb.zyads_users.cpcdeduction

Field: webdb.zyads_users.cpadeduction

Field: webdb.zyads_users.cpsdeduction

Field: webdb.zyads_users.cpvdeduction

Field: webdb.zyads_users.cpczlink

Field: webdb.zyads_users.cpazlink

Field: webdb.zyads_users.cpszlink

End

|| 0 | 0 | 0 | 0 | 0 | 1 | 1 | 1 ||

End

127.0.0.1.37968 > server: COM_QUERY: SELECT a.adsid,a.url,a.status,adstype,p.planid,p.deduction,p.plantype,p.price,p.priceadv,p.uid,p.expire,p.clearing,p.budget,u.money As advmoney,u.uid AS advuid FROM zyads_ads AS a ,zyads_plan As p ,zyads_users As u

WHERE a.adsid=26 AND a.planid=p.planid AND p.uid=u.uid AND  p.status = 1 AND  a.status = 3 AND u.status=2 limit 0,1

server > 127.0.0.1.37968: 15 Fields

Field: webdb.a.adsid

Field: webdb.a.url