Can't start server: Bind on TCP/IP port: Permission denied 问题的解决

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背景：

业务自己安装了一个percona分支的mysql server 5.7.25版本，端口号配置为3307，后来业务发现自己电脑与该机器有防火墙限制，想通过443或80端口绕过防火墙限制，于是将配置文件中的端口号改成443，如下：

启动命令如下：

shell> /home/work/mysql_3307/bin/mysqld_safe --defaults-file=/home/work/mysql_3307/etc/my.cnf  &

my.cnf文件内容部分如下：

[client]
port = 443
socket = /home/work/mysql_3307/tmp/mysql.sock

[mysqld]
# 问题就出现在下面这一行配置，当特权端口< 1024的时候，需要 root 访问权限，而业务就是想通过443端口来绕过防火墙的限制，
user = work
port = 443
socket = /home/work/mysql_3307/tmp/mysql.sock
datadir = /home/work/mysql_3307/data
basedir = /home/work/mysql_3307
pid_file = /home/work/mysql_3307/tmp/mysql.pid
log-error = /home/work/mysql_3307/log/mysql.err
default-time-zone                                               = "+08:00"
thread_handling                                                 = pool-of-threads
thread_pool_stall_limit                                         = 50
thread_pool_oversubscribe                                       = 20
performance_schema                                              = 1
log_slave_updates
log_timestamps                                                  = SYSTEM
general_log = /home/work/mysql_3307/log/mysql.log
general_log = /home/work/mysql_3307/log/mysql.log
log_warnings
slow_query_log
slow_query_log_file = /home/work/mysql_3307/log/slow.log
tmpdir = /home/work/mysql_3307/tmp

查看mysql的错误日志：

shell> less /home/work/mysql_3307/log/mysql.err

2021-09-10T11:59:39.494044+08:00 0 [Warning] option 'general_log': boolean value '/home/work/mysql_3307/log/mysql.log' wasn't recognized. Set to OFF.
2021-09-10T11:59:39.494128+08:00 0 [Warning] option 'general_log': boolean value '/home/work/mysql_3307/log/mysql.log' wasn't recognized. Set to OFF.
2021-09-10T11:59:39.494142+08:00 0 [Warning] The syntax '--log_warnings/-W' is deprecated and will be removed in a future release. Please use '--log_error_verbosity' instead.
2021-09-10T11:59:39.494526+08:00 0 [Warning] TIMESTAMP with implicit DEFAULT value is deprecated. Please use --explicit_defaults_for_timestamp server option (see documentation for more details).
2021-09-10T11:59:39.494572+08:00 0 [Note] --secure-file-priv is set to NULL. Operations related to importing and exporting data are disabled
2021-09-10T11:59:39.494612+08:00 0 [Note] /home/work/mysql_3307/bin/mysqld (mysqld 5.7.25-28-log) starting as process 167258 ...
2021-09-10T11:59:39.503292+08:00 0 [Warning] option 'innodb-buffer-pool-chunk-size': unsigned value 128 adjusted to 1048576
2021-09-10T11:59:39.504031+08:00 0 [Note] InnoDB: PUNCH HOLE support available
2021-09-10T11:59:39.504054+08:00 0 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins
2021-09-10T11:59:39.504063+08:00 0 [Note] InnoDB: Uses event mutexes
2021-09-10T11:59:39.504071+08:00 0 [Note] InnoDB: GCC builtin __atomic_thread_fence() is used for memory barrier
2021-09-10T11:59:39.504082+08:00 0 [Note] InnoDB: Compressed tables use zlib 1.2.7
2021-09-10T11:59:39.507458+08:00 0 [Note] InnoDB: Number of pools: 1
2021-09-10T11:59:39.507618+08:00 0 [Note] InnoDB: Using CPU crc32 instructions
2021-09-10T11:59:39.510419+08:00 0 [Note] InnoDB: Initializing buffer pool, total size = 10G, instances = 8, chunk size = 1M
2021-09-10T11:59:39.991718+08:00 0 [Note] InnoDB: Completed initialization of buffer pool
2021-09-10T11:59:40.063282+08:00 0 [Note] InnoDB: If the mysqld execution user is authorized, page cleaner thread priority can be changed. See the man page of setpriority().
2021-09-10T11:59:40.075849+08:00 0 [Note] InnoDB: Crash recovery did not find the parallel doublewrite buffer at /home/work/mysql_3307/data/xb_doublewrite
2021-09-10T11:59:40.077084+08:00 0 [Note] InnoDB: Opened 3 undo tablespaces
2021-09-10T11:59:40.077104+08:00 0 [Note] InnoDB: 3 undo tablespaces made active
2021-09-10T11:59:40.077505+08:00 0 [Note] InnoDB: Highest supported file format is Barracuda.
2021-09-10T11:59:40.148881+08:00 0 [Note] InnoDB: Created parallel doublewrite buffer at /home/work/mysql_3307/data/xb_doublewrite, size 31457280 bytes
2021-09-10T11:59:40.320501+08:00 0 [Note] InnoDB: Creating shared tablespace for temporary tables
2021-09-10T11:59:40.320607+08:00 0 [Note] InnoDB: Setting file './ibtmp1' size to 12 MB. Physically writing the file full; Please wait ...
2021-09-10T11:59:40.326149+08:00 0 [Note] InnoDB: File './ibtmp1' size is now 12 MB.
2021-09-10T11:59:40.327480+08:00 0 [Note] InnoDB: 96 redo rollback segment(s) found. 96 redo rollback segment(s) are active.
2021-09-10T11:59:40.327496+08:00 0 [Note] InnoDB: 32 non-redo rollback segment(s) are active.
2021-09-10T11:59:40.327981+08:00 0 [Note] InnoDB: Waiting for purge to start
2021-09-10T11:59:40.378141+08:00 0 [Note] InnoDB: Percona XtraDB (http://www.percona.com) 5.7.25-28 started; log sequence number 2504477
2021-09-10T11:59:40.378254+08:00 0 [Note] InnoDB: Loading buffer pool(s) from /home/work/mysql_3307/data/ib_buffer_pool
2021-09-10T11:59:40.378487+08:00 0 [Note] Plugin 'FEDERATED' is disabled.
2021-09-10T11:59:40.410408+08:00 0 [Note] InnoDB: Buffer pool(s) load completed at 210910 11:59:40
2021-09-10T11:59:40.410792+08:00 0 [Warning] Failed to set up SSL because of the following SSL library error: SSL context is not usable without certificate and private key
2021-09-10T11:59:40.410817+08:00 0 [Note] Server hostname (bind-address): '*'; port: 443
2021-09-10T11:59:40.410869+08:00 0 [Note] IPv6 is available.
2021-09-10T11:59:40.410888+08:00 0 [Note]   - '::' resolves to '::';
2021-09-10T11:59:40.410906+08:00 0 [Note] Server socket created on IP: '::'.
2021-09-10T11:59:40.410944+08:00 0 [ERROR] Can't start server: Bind on TCP/IP port: Permission denied
2021-09-10T11:59:40.410951+08:00 0 [ERROR] Do you already have another mysqld server running on port: 443 ?
2021-09-10T11:59:40.410963+08:00 0 [ERROR] Aborting

问题根本原因：

特权端口：是指在 Linux 系统下，只允许 root 用户运行的程序才可以使用特权端口 ( 1024 以下的端口 )。如果在普通用户下使用特权端口将会报错。

业务使用的443端口，很明显是小于1024的，因此是特权端口，这就要求启动进程的时候，必须以root身份启动，但是my.cnf文件中指定work用户（一般用户）来启动，那肯定就不是root用户了，因此无法启动，但是mysql这个报错内容让人摸不着头脑

解决问题：将配置文件中的user=work改成user=root，然后用root用户执行：

root-shell> /home/work/mysql_3307/bin/mysqld_safe --defaults-file=/home/work/mysql_3307/etc/my.cnf &

/home/work/mysql_3307/etc/my.cnf文件内容如下：

[client]
port = 443
socket = /home/work/mysql_3307/tmp/mysql.sock

[mysqld]
# 将work改成rootuser = root
port = 443
socket = /home/work/mysql_3307/tmp/mysql.sock
datadir = /home/work/mysql_3307/data
basedir = /home/work/mysql_3307
pid_file = /home/work/mysql_3307/tmp/mysql.pid
log-error = /home/work/mysql_3307/log/mysql.err
default-time-zone                                               = "+08:00"
thread_handling                                                 = pool-of-threads
thread_pool_stall_limit                                         = 50
thread_pool_oversubscribe                                       = 20
performance_schema                                              = 1
log_slave_updates
log_timestamps                                                  = SYSTEM
general_log = /home/work/mysql_3307/log/mysql.log
general_log = /home/work/mysql_3307/log/mysql.log
log_warnings
slow_query_log
slow_query_log_file = /home/work/mysql_3307/log/slow.log
tmpdir = /home/work/mysql_3307/tmp

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