免密码登录有的成功，有的失败是怎么回事儿

V2EX = way to explore

V2EX 是一个关于分享和探索的地方

现在注册

已注册用户请登录

这是一个创建于 3438 天前的主题，其中的信息可能已经有所发展或是发生改变。

自己创建了一台centos 6.5的虚拟机，然后克隆了3台，修改了ip，都可以互相ping通，都可以连外网。但我想让这几台都SSH无密码访问，可是同样的操作，ssh-keygen -t rsa,将第一台的公钥拷贝到了其他三台的authoried_keys,

结果第一台和第二台成功免密钥登录，而第一台登录其他两台不行，都需要密码。这是为什么呢？

ssh

密码

4 条回复 • 2021-03-12 17:50:23 +08:00

kaneg

2015-07-22 23:59:54 +08:00 via iPhone

ssh -v xxx看输出什么

jiaqidianbo

2015-07-23 00:14:15 +08:00

@kaneg

[root@newmaster .ssh]# ssh -v newnode3
OpenSSH_5.3p1, OpenSSL 1.0.1e-fips 11 Feb 2013
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: Applying options for *
debug1: Connecting to newnode3 [192.168.1.25] port 22.
debug1: Connection established.
debug1: permanently_set_uid: 0/0
debug1: identity file /root/.ssh/identity type -1
debug1: identity file /root/.ssh/identity-cert type -1
debug1: identity file /root/.ssh/id_rsa type 1
debug1: identity file /root/.ssh/id_rsa-cert type -1
debug1: identity file /root/.ssh/id_dsa type -1
debug1: identity file /root/.ssh/id_dsa-cert type -1
debug1: Remote protocol version 2.0, remote software version OpenSSH_5.3
debug1: match: OpenSSH_5.3 pat OpenSSH*
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_5.3
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug1: kex: server->client aes128-ctr hmac-md5 none
debug1: kex: client->server aes128-ctr hmac-md5 none
debug1: SSH2_MSG_KEX_DH_GEX_REQUEST(1024<1024<8192) sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_GROUP
debug1: SSH2_MSG_KEX_DH_GEX_INIT sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY
debug1: Host 'newnode3' is known and matches the RSA host key.
debug1: Found key in /root/.ssh/known_hosts:3
debug1: ssh_rsa_verify: signature correct
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug1: SSH2_MSG_NEWKEYS received
debug1: SSH2_MSG_SERVICE_REQUEST sent
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug1: Authentications that can continue: publickey,gssapi-keyex,gssapi-with-mic,password
debug1: Next authentication method: gssapi-keyex
debug1: No valid Key exchange context
debug1: Next authentication method: gssapi-with-mic
debug1: Unspecified GSS failure. Minor code may provide more information
Credentials cache file '/tmp/krb5cc_0' not found

debug1: Unspecified GSS failure. Minor code may provide more information
Credentials cache file '/tmp/krb5cc_0' not found

debug1: Unspecified GSS failure. Minor code may provide more information

debug1: Unspecified GSS failure. Minor code may provide more information
Credentials cache file '/tmp/krb5cc_0' not found

debug1: Next authentication method: publickey
debug1: Trying private key: /root/.ssh/identity
debug1: Offering public key: /root/.ssh/id_rsa
debug1: Authentications that can continue: publickey,gssapi-keyex,gssapi-with-mic,password
debug1: Trying private key: /root/.ssh/id_dsa
debug1: Next authentication method: password

root@newnode3's password:

kaneg

2015-07-23 22:46:09 +08:00

从 debug1: Offering public key: /root/.ssh/id_rsa 一行来看，客户端已经尝试发送RSA public 方式登录，但未成功，所以问题很有可能在服务端。一般来说，可能是服务端~/.ssh/authorized_keys的权限不对。不过为了查到正真的原因，需要如下方法：
将ssh日志调为debug模式：修改/etc/ssh/sshd_config，将LogLevel INFO 改为LogLevel DEBUG
重启ssh 服务： service ssh restart
然后一边登录，一边观察/var/log/auth.log，一般来说错误原因就在其中。

awanganddong

2021-03-12 17:50:23 +08:00

标记以下，现在也出现问题，学习下判断方法