Ubuntu
為什麼我無法以 root 身份 ssh？
我是同一防火牆下的兩台伺服器A和B。我可以使用 root 帳戶從伺服器 A 登錄到 B，但我無法從 B 登錄到 A。我的 ssh 密鑰已正確配置，但我無法弄清楚我們出了什麼問題。
這是我嘗試從伺服器 B 連接到 A 時的詳細資訊。
root@web04:~# ssh -v -i.ssh/id_rsa root@11.11.11.4 OpenSSH_5.9p1 Debian-5ubuntu1.4, OpenSSL 1.0.1 14 Mar 2012 Warning: Identity file .ssh/id_rsa not accessible: No such file or directory. debug1: Reading configuration data /etc/ssh/ssh_config debug1: /etc/ssh/ssh_config line 19: Applying options for * debug1: Connecting to 11.11.11.4 [11.11.11.4] port 22. debug1: Connection established. debug1: permanently_set_uid: 0/0 debug1: identity file /root/.ssh/id_rsa type -1 debug1: identity file /root/.ssh/id_rsa-cert type -1 debug1: read_keyfile_line: /root/.ssh/id_dsa.pub line 1 exceeds size limit debug1: identity file /root/.ssh/id_dsa type -1 debug1: identity file /root/.ssh/id_dsa-cert type -1 debug1: identity file /root/.ssh/id_ecdsa type -1 debug1: identity file /root/.ssh/id_ecdsa-cert type -1 debug1: Remote protocol version 2.0, remote software version OpenSSH_5.9p1 Debian-5ubuntu1.4 debug1: match: OpenSSH_5.9p1 Debian-5ubuntu1.4 pat OpenSSH* debug1: Enabling compatibility mode for protocol 2.0 debug1: Local version string SSH-2.0-OpenSSH_5.9p1 Debian-5ubuntu1.4 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: sending SSH2_MSG_KEX_ECDH_INIT debug1: expecting SSH2_MSG_KEX_ECDH_REPLY debug1: Server host key: ECDSA 2c:37:bc:c8:47:07:53:07:9c:a8:f8:1d:12:a6:4a:a0 debug1: Host '11.11.11.4' is known and matches the ECDSA host key. debug1: Found key in /root/.ssh/known_hosts:11 debug1: ssh_ecdsa_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 Ubuntu 12.04 LTS ------------------------------------- UNAUTHORISED ACCESS IS PROHIBITED!! ------------------------------------- debug1: Authentications that can continue: publickey,password debug1: Next authentication method: publickey debug1: Trying private key: /root/.ssh/id_rsa debug1: Trying private key: /root/.ssh/id_dsa debug1: read PEM private key done: type DSA debug1: Authentications that can continue: publickey,password debug1: Trying private key: /root/.ssh/id_ecdsa debug1: Next authentication method: passwor
請檢查 /etc/ssh/sshd_config 中的“PermitRootLogin”選項是否設置為“yes”。
請注意，這通常設置為“no”或“public-key”，因為通過 SSH 以 root 身份登錄被廣泛認為是一個安全問題。