Linux 特定计算机的ssh登录权限被拒绝

我尝试通过ssh从3台机器（a、B和C）登录服务器。a来自我家，B和C来自学校网络。我可以从A和B登录ssh服务器，但不能从C登录。在主机C上，我得到以下信息：

debug1: SSH2_MSG_KEX_DH_GEX_INIT sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY
debug1: Host 'mynet.com' is known and matches the RSA host key.
debug1: Found key in /home/myname/.ssh/known_hosts:1
debug1: ssh_rsa_verify: signature correct
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug1: SSH2_MSG_NEWKEYS received
debug1: Roaming not allowed by server
debug1: SSH2_MSG_SERVICE_REQUEST sent
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug1: Authentications that can continue: publickey,password
debug1: Next authentication method: publickey
debug1: Trying private key: /home/myname/.ssh/id_rsa
debug1: Trying private key: /home/myname/.ssh/id_dsa
debug1: Next authentication method: password
ssh_userA@mynet.com's password: 
debug1: Authentications that can continue: publickey,password
Permission denied, please try again.
ssh_userA@mynet.com's password: 

我已经在ssh服务器上完成了以下操作

我已将/etc/hosts.allow和/etc/hosts.deny更改为另一个临时名称，并重新加载了/etc/init.d/ssh

我已经做了iptables-F来清理所有的防火墙规则，并做了iptables-L来验证它是否全部打开

我确信ssh_userA的密码是正确的，因为我可以使用它从A和B登录。我还尝试添加一个新用户ssh_userB。问题仍然存在，只有主机C给了我一个权限被拒绝的问题。但是，我可以从主机C成功登录到另一个ssh服务器

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主机A和C是debian，B是centOS。

胡乱猜测。可能在同一网络中使用内部IP？

检查/etc/ssh/sshd\u config Centos中的AllowUsers指令，这可以设置user@ipSSH访问的级别