我想在两台 Linux 机器之间建立 SSH 连接：客户端和服务器。我在两台机器上都使用 root 帐户，它们的 Linux 发行版是 CentOS 7。
我使用以下命令为 SSH 生成了一对私钥-公钥ssh-keygen -t rsa。它生成了密钥文件id_rsa& id_rsa.pub。我将 的内容附加id_rsa.pub到/root/.ssh/authorized_keys服务器端，并将 上传id_rsa到/root/.ssh/id_rsa客户端。
ssh 连接失败Permission denied (publickey)。以下是完整的详细输出：
$ ssh -vvv root@<server-ip>
OpenSSH_6.6.1, OpenSSL 1.0.1e-fips 11 Feb 2013
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 56: Applying options for *
debug2: ssh_connect: needpriv 0
debug1: Connecting to <server-ip> [<server-ip>] port 22.
debug1: Connection established.
debug1: permanently_set_uid: 0/0
debug3: Incorrect RSA1 identifier
debug3: Could not load "/root/.ssh/id_rsa" as a RSA1 public key
debug1: identity file /root/.ssh/id_rsa type 1
debug1: identity file /root/.ssh/id_rsa-cert type -1
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_6.6.1
debug1: Remote protocol version 2.0, remote software version OpenSSH_6.4
debug1: match: OpenSSH_6.4 pat OpenSSH* compat 0x04000000
debug2: fd 3 setting O_NONBLOCK
debug3: load_hostkeys: loading entries for host "<server-ip>" from file "/root/.ssh/known_hosts"
debug3: load_hostkeys: found key type ECDSA in file /root/.ssh/known_hosts:1
debug3: load_hostkeys: loaded 1 keys
debug3: order_hostkeyalgs: prefer hostkeyalgs: [email protected],[email protected],[email protected],ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug2: kex_parse_kexinit: [email protected],ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1
debug2: kex_parse_kexinit: [email protected],[email protected],[email protected],ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,[email protected],[email protected],[email protected],[email protected],[email protected],ssh-ed25519,ssh-rsa,ssh-dss
debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,[email protected],[email protected],[email protected],aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,[email protected]
debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,[email protected],[email protected],[email protected],aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,[email protected]
debug2: kex_parse_kexinit: [email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],hmac-md5,hmac-sha1,[email protected],[email protected],hmac-sha2-256,hmac-sha2-512,hmac-ripemd160,[email protected],hmac-sha1-96,hmac-md5-96
debug2: kex_parse_kexinit: [email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],hmac-md5,hmac-sha1,[email protected],[email protected],hmac-sha2-256,hmac-sha2-512,hmac-ripemd160,[email protected],hmac-sha1-96,hmac-md5-96
debug2: kex_parse_kexinit: none,[email protected],zlib
debug2: kex_parse_kexinit: none,[email protected],zlib
debug2: kex_parse_kexinit:
debug2: kex_parse_kexinit:
debug2: kex_parse_kexinit: first_kex_follows 0
debug2: kex_parse_kexinit: reserved 0
debug2: kex_parse_kexinit: ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1
debug2: kex_parse_kexinit: ssh-rsa,ecdsa-sha2-nistp256
debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,[email protected],[email protected],aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,[email protected]
debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,[email protected],[email protected],aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,[email protected]
debug2: kex_parse_kexinit: [email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],hmac-md5,hmac-sha1,[email protected],[email protected],hmac-sha2-256,hmac-sha2-512,hmac-ripemd160,[email protected],hmac-sha1-96,hmac-md5-96
debug2: kex_parse_kexinit: [email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],hmac-md5,hmac-sha1,[email protected],[email protected],hmac-sha2-256,hmac-sha2-512,hmac-ripemd160,[email protected],hmac-sha1-96,hmac-md5-96
debug2: kex_parse_kexinit: none,[email protected]
debug2: kex_parse_kexinit: none,[email protected]
debug2: kex_parse_kexinit:
debug2: kex_parse_kexinit:
debug2: kex_parse_kexinit: first_kex_follows 0
debug2: kex_parse_kexinit: reserved 0
debug2: mac_setup: setup [email protected]
debug1: kex: server->client aes128-ctr [email protected] none
debug2: mac_setup: setup [email protected]
debug1: kex: client->server aes128-ctr [email protected] none
debug1: kex: ecdh-sha2-nistp256 need=16 dh_need=16
debug1: kex: ecdh-sha2-nistp256 need=16 dh_need=16
debug1: sending SSH2_MSG_KEX_ECDH_INIT
debug1: expecting SSH2_MSG_KEX_ECDH_REPLY
debug1: Server host key: ECDSA <fingerprint>
debug3: load_hostkeys: loading entries for host "<server-ip>" from file "/root/.ssh/known_hosts"
debug3: load_hostkeys: found key type ECDSA in file /root/.ssh/known_hosts:1
debug3: load_hostkeys: loaded 1 keys
debug1: Host '<server-ip>' is known and matches the ECDSA host key.
debug1: Found key in /root/.ssh/known_hosts:1
debug1: ssh_ecdsa_verify: signature correct
debug2: kex_derive_keys
debug2: set_newkeys: mode 1
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug2: set_newkeys: mode 0
debug1: SSH2_MSG_NEWKEYS received
debug1: Roaming not allowed by server
debug1: SSH2_MSG_SERVICE_REQUEST sent
debug2: service_accept: ssh-userauth
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug2: key: /root/.ssh/id_rsa (0x7fb088838a90), explicit
debug1: Authentications that can continue: publickey
debug3: start over, passed a different list publickey
debug3: preferred gssapi-keyex,gssapi-with-mic,publickey,keyboard-interactive,password
debug3: authmethod_lookup publickey
debug3: remaining preferred: keyboard-interactive,password
debug3: authmethod_is_enabled publickey
debug1: Next authentication method: publickey
debug1: Offering RSA public key: /root/.ssh/id_rsa
debug3: send_pubkey_test
debug2: we sent a publickey packet, wait for reply
debug1: Server accepts key: pkalg ssh-rsa blen 279
debug2: input_userauth_pk_ok: fp <fingerprint>
debug3: sign_and_send_pubkey: RSA <fingerprint>
debug1: key_parse_private2: missing begin marker
debug1: read PEM private key done: type RSA
debug1: Authentications that can continue: publickey
debug2: we did not send a packet, disable method
debug1: No more authentication methods to try.
Permission denied (publickey).
我认为最重要的一行是：debug1: key_parse_private2: missing begin marker。我上网查了一下，发现有人说服务器端日志更重要。所以我去检查了/var/log/secure服务器端。以下是我发现的内容：
localhost sshd[21061]: error: RSA_public_decrypt failed: error:0407006A:lib(4):func(112):reason(106)
localhost sshd[21061]: Connection closed by <client-ip> [preauth]
我发现这个命令可以更深入地了解这个错误的含义：
$ openssl errstr 0407006A
error:0407006A:rsa routines:RSA_padding_check_PKCS1_type_1:block type is not 01
现在事情开始变得有趣了。使用相同的 SSH 私钥，我能够使用第二台客户端计算机成功连接到服务器。这台计算机是 Windows 计算机，我通过指定私钥的路径与 mobaxterm 连接。
回到原来的客户端机器，我决定将同一个私钥重新上传到文件系统的其他位置（在目录中/root/18-4-2016）。然后......惊喜......连接正常了。
$ ssh -i ~/18-4-2016/id_rsa root@<server-ip>工作过
$ ssh -i ~/.ssh/id_rsa root@<server-ip>仍然因同样的错误而失败。
我试图找出两个文件之间的差异，但没有成功：
$ diff ~/.ssh/id_rsa ~/18-4-2016/id_rsa
$
$ ll ~/.ssh/id_rsa ~/18-4-2016/id_rsa
-rw-------. 1 root root 1679 Apr 19 10:16 /root/18-4-2016/id_rsa
-rw-------. 1 root root 1679 Apr 19 10:07 /root/.ssh/id_rsa
答案1
我回答我自己的问题
问题的根源是/root/.ssh/id_rsa.pub客户端的一个旧文件。我删除了这个文件，它就正常工作了。
在我的自定义密钥文件夹（/root/18-4-2016/）中，没有任何的id_rsa.pub副本id_rsa，解释为什么在使用该特定密钥文件时它可以工作。
我还通过将正确的公钥从服务器端复制到/root/.ssh/id_rsa.pub客户端进行了测试，而不是简单地删除公钥文件。它也工作正常。
ssh 客户端使用公钥，这很奇怪。
我向 openssh 邮件列表发送了一封电子邮件：https://lists.mindrot.org/pipermail/openssh-unix-dev/2016-April/035048.html