我在 Amazon EC2 上有一个 ubuntu 服务器。以前我使用在实例启动时生成的原始 pem 密钥文件登录。
ssh -i /path/to/key.pem [email protected]
我尝试停止密码验证，并在 sshd_config 中做了以下更改。
ChallengeResponseAuthentication no
PasswordAuthentication no
UsePAM no
轰隆隆。密钥登录停止工作，并显示“权限被拒绝（公钥）”错误。
有趣的是，我使用 ssh-keygen 为非 root 用户创建了一个 rsa 密钥。现在仍然可以使用。但 ec2 pem 密钥文件不起作用。
注意：如果我将 UsePam 更改为“是”，则 pem 密钥将再次开始起作用。我能够在另一台机器上重现此问题。但是，在第一台机器上，由于密钥文件不起作用，我失去了获得 root 权限的能力。因此无法对 sshd_config 文件进行任何更改。
ssh 日志如下所示。
OpenSSH_5.9p1 Debian-5ubuntu1.1, OpenSSL 1.0.1 14 Mar 2012
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 19: Applying options for *
debug2: ssh_connect: needpriv 0
debug1: Connecting to ec2-xx.xx.us-west-2.compute.amazonaws.com [xx.xx.xx.xx] port 22.
debug1: Connection established.
debug3: Incorrect RSA1 identifier
debug3: Could not load "/home/amitoj/.ssh/backupshard.pem" as a RSA1 public key
debug1: identity file /home/amitoj/.ssh/backupshard.pem type -1
debug1: identity file /home/amitoj/.ssh/backupshard.pem-cert type -1
debug1: Remote protocol version 2.0, remote software version OpenSSH_5.9p1Debian- 5ubuntu1.1
debug1: match: OpenSSH_5.9p1 Debian-5ubuntu1.1 pat OpenSSH*
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_5.9p1 Debian-5ubuntu1.1
debug2: fd 3 setting O_NONBLOCK
debug3: load_hostkeys: loading entries for host "ec2-xx.xx.xx.xx.us- west-2.compute.amazonaws.com" from file "/home/amitoj/.ssh/known_hosts"
debug3: load_hostkeys: found key type ECDSA in file /home/amitoj/.ssh/known_hosts:70
debug3: load_hostkeys: loaded 1 keys
debug3: order_hostkeyalgs: prefer hostkeyalgs: ecdsa-sha2-nistp256- [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: 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],ssh-rsa,ssh-dss
debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,[email protected]
debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,[email protected]
debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,[email protected],hmac-sha2-256,hmac-sha2-256-96,hmac-sha2-512,hmac-sha2-512-96,hmac-ripemd160,[email protected],hmac-sha1-96,hmac-md5-96
debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,[email protected],hmac-sha2-256,hmac-sha2-256-96,hmac-sha2-512,hmac-sha2-512-96,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,ecdhsha2-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,ssh-dss,ecdsa-sha2-nistp256
debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,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,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256cbc,arcfour,[email protected]
debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,[email protected],hmac-sha2-256,hmac-sha2-256-96,hmac-sha2-512,hmac-sha2-512-96,hmac-ripemd160,[email protected],hmac-sha1-96,hmac-md5-96
debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,[email protected],hmac-sha2-256,hmac-sha2-256-96,hmac-sha2-512,hmac-sha2-512-96,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: found hmac-md5
debug1: kex: server->client aes128-ctr hmac-md5 none
debug2: mac_setup: found hmac-md5
debug1: kex: client->server aes128-ctr hmac-md5 none
debug1: sending SSH2_MSG_KEX_ECDH_INIT
debug1: expecting SSH2_MSG_KEX_ECDH_REPLY
debug1: Server host key: ECDSA 2d:19:d0:63:49:d9:f7:30:26:3f:6e:ff:8e:63:4d:c5
debug3: load_hostkeys: loading entries for host "ec2-xx.xx.xx.uswest-2.compute.amazonaws.com" from file "/home/amitoj/.ssh/known_hosts"
debug3: load_hostkeys: found key type ECDSA in file /home/amitoj/.ssh/known_hosts:70
debug3: load_hostkeys: loaded 1 keys
debug3: load_hostkeys: loading entries for host "xx.xx.xx.xx" from file "/home/amit/.ssh/known_hosts"
debug3: load_hostkeys: found key type ECDSA in file /home/amitoj/.ssh/known_hosts:71
debug3: load_hostkeys: loaded 1 keys
debug1: Host 'ec2-xx.xx.xx.xx.us-west-2.compute.amazonaws.com' is known and matches the ECDSA host key.
debug1: Found key in /home/amitoj/.ssh/known_hosts:70
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: /home/amitoj/.ssh/backupshard.pem ((nil))
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: Trying private key: /home/amitoj/.ssh/backupshard.pem
debug1: read PEM private key done: type RSA
debug3: sign_and_send_pubkey: RSA 69:ff:93:01:27:57:00:23:6e:2b:90:72:16:15:65:bb
debug2: we sent a publickey packet, wait for reply
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).
关于如何使用“pem”密钥文件获得 root 用户权限，您有什么想法吗？
答案1
在下一次实例化时，使用“CloudInit”功能之一并提供用户数据脚本这将编辑/修复“sshd_config”。一个简单的“sed”命令就可以了。