1. rsync服务端开启的iptables防火墙
    客户端的错误现象：No route to host
    [root@nfs01 tmp]# rsync -avz /etc/hosts [email protected]::backup
    rsync: failed to connect to 172.16.1.41: No route to host (113)
    rsync error: error in socket IO (code 10) at clientserver.c(124) [sender=3.0.6]
    异常问题解决：
    关闭rsync服务端的防火墙服务（iptables）
    [root@backup mnt]# /etc/init.d/iptables stop
    iptables: Setting chains to policy ACCEPT: filter [ OK ]
    iptables: Flushing firewall rules: [ OK ]
    iptables: Unloading modules: [ OK ]
    [root@backup mnt]# /etc/init.d/iptables status
    iptables: Firewall is not running.

  2. rsync客户端执行rsync命令错误：
    客户端的错误现象：
    [root@nfs01 tmp]# rsync -avz /etc/hosts [email protected]::/backup
    ERROR: The remote path must start with a module name not a /
    rsync error: error starting client-server protocol (code 5) at main.c(1503) [sender=3.0.6]
    异常问题解决：
    rsync命令语法理解错误，::/backup是错误的语法，应该为::backup(rsync模块)

  3. @ERROR: auth failed on module oldboy
    客户端的错误现象：
    [root@nfs01 tmp]# rsync -avz /etc/hosts [email protected]::backup
    Password:
    @ERROR: auth failed on module backup
    rsync error: error starting client-server protocol (code 5) at main.c(1503) [sender=3.0.6]
    异常问题解决：

    1. 密码真的输入错误，用户名真的错误
    2. secrets file = /etc/rsync.password指定的密码文件和实际密码文件名称不一致
    3. /etc/rsync.password文件权限不是600
    4. rsync_backup:123456密码配置文件后面注意不要有空格
    5. rsync客户端密码文件中只输入密码信息即可，不要输入虚拟认证用户名称

  4. Unknown module 'backup'
    [root@nfs01 tmp]# rsync -avz /etc/hosts [email protected]::backup
    @ERROR: Unknown module 'backup'
    rsync error: error starting client-server protocol (code 5) at main.c(1503) [sender=3.0.6]
    异常问题解决：

    1. /etc/rsyncd.conf配置文件模块名称书写错误
  5. Permission denied
    [root@nfs01 tmp]# rsync -avz /etc/hosts [email protected]::backup
    Password:
    sending incremental file list
    hosts
    rsync: mkstemp ".hosts.5z3AOA" (in backup) failed: Permission denied (13)

sent 196 bytes received 27 bytes 63.71 bytes/sec
total size is 349 speedup is 1.57
rsync error: some files/attrs were not transferred (see previous errors) (code 23) at main.c(1039) [sender=3.0.6]
异常问题解决：

  1. 共享目录的属主和属组不正确，不是rsync
  2. 共享目录的权限不正确，不是755

  1. chdir failed
    [root@nfs01 tmp]# rsync -avz /etc/hosts [email protected]::backup
    Password:
    @ERROR: chdir failed
    rsync error: error starting client-server protocol (code 5) at main.c(1503) [sender=3.0.6]
    异常问题解决：

    1. 备份存储目录没有建立
    2. 建立的备份存储目录和配置文件定义不一致
      [root@backup backup]# /etc/init.d/xinetd restart
      shell-init: error retrieving current directory: getcwd: cannot access parent directories: No such file or directory
      Stopping xinetd: [ OK ]
      Starting xinetd: shell-init: error retrieving current directory: getcwd: cannot access parent directories: No such file or directory
      [ OK ]
      说明：如果没有备份存储目录，xinetd服务都不能正确启动

  2. invalid uid rsync
    [root@nfs01 tmp]# rsync -avz /etc/hosts [email protected]::backup
    Password:
    @ERROR: invalid uid rsync
    rsync error: error starting client-server protocol (code 5) at main.c(1503) [sender=3.0.6]
    异常问题解决：
    rsync服务对应rsync虚拟用户不存在了

  3. 客户端已经配置了密码文件，但免秘钥登录方式，依旧需要输入密码
    password file must not be other-accessible
    [root@nfs01 tmp]# rsync -avz /etc/hosts [email protected]::backup --password-file=/etc/rsync.password
    password file must not be other-accessible
    continuing without password file
    Password:
    sending incremental file list

sent 26 bytes received 8 bytes 5.23 bytes/sec
total size is 349 speedup is 10.26
异常问题解决：
rsync客户端的秘钥文件也必须是600权限

  1. rsync客户端连接慢问题
    错误日志输出
    2017/03/08 20:14:43 [3422] params.c:Parameter() - Ignoring badly formed line in configuration file: ignore errors
    2017/03/08 20:14:43 [3422] name lookup failed for 172.16.1.31: Name or service not known
    2017/03/08 20:14:43 [3422] connect from UNKNOWN (172.16.1.31)
    2017/03/08 20:14:43 [3422] rsync to backup/ from rsync_backup@unknown (172.16.1.31)
    2017/03/08 20:14:43 [3422] receiving file list
    2017/03/08 20:14:43 [3422] sent 76 bytes received 83 bytes total size 349
    正确日志输出
    2017/03/08 20:16:45 [3443] params.c:Parameter() - Ignoring badly formed line in configuration file: ignore errors
    2017/03/08 20:16:45 [3443] connect from nfs02 (172.16.1.31)
    2017/03/08 20:16:45 [3443] rsync to backup/ from rsync_backup@nfs02 (172.16.1.31)
    2017/03/08 20:16:45 [3443] receiving file list
    2017/03/08 20:16:45 [3443] sent 76 bytes received 83 bytes total size 349
    异常问题解决：
    查看日志进行分析

10 rsync服务没有正确启动
Connection refused (111)
[root@oldboy-muban ~]# rsync -avz /etc/hosts [email protected]::backup
rsync: failed to connect to 172.16.1.41: Connection refused (111)
rsync error: error in socket IO (code 10) at clientserver.c(124) [sender=3.0.6]
解决 rsync服务没开启
[root@oldboy-muban ~]# rsync --daemon
[root@oldboy-muban ~]# ss -lntup |grep rsync
tcp LISTEN 0 5 :::873 ::: users:(("rsync",1434,5))
tcp LISTEN 0 5 :873 : users:(("rsync",1434,4))
[root@oldboy-muban ~]# rsync -avz /etc/hosts [email protected]::backup
Password:
sending incremental file list
hosts

sent 196 bytes received 27 bytes 49.56 bytes/sec
total size is 349 speedup is 1.57