使用Desktop 版ubuntu 16.04.3 LTS 做云服務器的小坑

家里一臺2011年的老機器（Acer x3960，i5-2300, 8G RAM, 120G SSD）放了很久沒有用，現(xiàn)在突然有需求在墻外部署一臺機器給國內(nèi)的小伙伴用。這機器老歸老，比t2.micro還是強得多。收拾一下，裝個ubuntu準備接客，發(fā)揮余熱。

因為放在家里，用電視當顯示器，想著哪天沒事自己還會在本地用一下，再加上那么多年和CDNS、SNPS廝混的X window情節(jié)，就裝了個桌面版ubuntu。

安裝沒有問題，配置上線也沒有問題，裝上ZeroTier，加入私網(wǎng)，不用在費心去做uPnP的路由器端口映射打洞。

上線后需要解決幾個問題：

  1. 開通ssh服務，加入ssh key。略過
  2. 修改suder
    sudu visudo
    加入下面這一行
    ubuntu ALL=(ALL) NOPASSWD: ALL
    參考 https://askubuntu.com/questions/147241/execute-sudo-without-password
  3. 奇怪的密碼登錄
    做完上面兩步，遠程可以正常ssh免密碼登錄，第一次用ansible playbook配置環(huán)境也全部成功。
    但是，日常使用卻時不時提示輸入密碼，很奇怪。有時要求輸入，有時直接進去。自己用也就算了，小伙伴們用起來很難受，而且還有ansible呢。
    開始debug：
    ssh 登錄時使用-v 選項，打印log，(敏感信息略過)
$ ssh -v ubuntu@10.10.10.10
OpenSSH_7.4p1, LibreSSL 2.5.0
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 53: Applying options for *
debug1: Connecting to 10.10.10.10 [10.10.10.10] port 22.
debug1: Connection established.
debug1: identity file /Users/perebor/.ssh/id_rsa type 1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/perebor/.ssh/id_rsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/perebor/.ssh/id_dsa type -1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/perebor/.ssh/id_dsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/perebor/.ssh/id_ecdsa type -1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/perebor/.ssh/id_ecdsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/perebor/.ssh/id_ed25519 type -1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/perebor/.ssh/id_ed25519-cert type -1
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_7.4
debug1: Remote protocol version 2.0, remote software version OpenSSH_7.2p2 Ubuntu-4ubuntu2.2
debug1: match: OpenSSH_7.2p2 Ubuntu-4ubuntu2.2 pat OpenSSH* compat 0x04000000
debug1: Authenticating to 10.10.10.10:22 as 'ubuntu'
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug1: kex: algorithm: curve25519-sha256@libssh.org
debug1: kex: host key algorithm: ecdsa-sha2-nistp256
debug1: kex: server->client cipher: chacha20-poly1305@openssh.com MAC: <implicit> compression: none
debug1: kex: client->server cipher: chacha20-poly1305@openssh.com MAC: <implicit> compression: none
debug1: expecting SSH2_MSG_KEX_ECDH_REPLY
debug1: Server host key: ecdsa-sha2-nistp256 SHA256:xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
debug1: Host '10.10.10.10' is known and matches the ECDSA host key.
debug1: Found key in /Users/perebor/.ssh/known_hosts:66
debug1: rekey after 134217728 blocks
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug1: SSH2_MSG_NEWKEYS received
debug1: rekey after 134217728 blocks
debug1: SSH2_MSG_EXT_INFO received
debug1: kex_input_ext_info: server-sig-algs=<rsa-sha2-256,rsa-sha2-512>
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug1: Authentications that can continue: publickey,password
debug1: Next authentication method: publickey
debug1: Offering RSA public key: /Users/perebor/.ssh/id_rsa
debug1: Authentications that can continue: publickey,password
debug1: Trying private key: /Users/perebor/.ssh/id_dsa
debug1: Trying private key: /Users/perebor/.ssh/id_ecdsa
debug1: Trying private key: /Users/perebor/.ssh/id_ed25519
debug1: Next authentication method: password
ubuntu@10.10.10.10's password:

發(fā)現(xiàn)問題是本地ssh client會使用不同的key嘗試登錄，但是三次以后服務器就返回提示輸入密碼。
因為服務器上sshd里面有密碼登錄這個選項。那我們關上他就好了。

到/etc/ssh/sshd_config 里面，把PasswordAuthentication改成no，

# Change to no to disable tunnelled clear text passwords
PasswordAuthentication no

然后重啟ssh服務

sudo service ssh restart

再次登錄，直接進入。

$ ssh -v ubuntu@10.10.10.10
OpenSSH_7.4p1, LibreSSL 2.5.0
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 53: Applying options for *
debug1: Connecting to 10.10.10.10 [10.10.10.10] port 22.
debug1: Connection established.
debug1: identity file /Users/perebor/.ssh/id_rsa type 1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/perebor/.ssh/id_rsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/perebor/.ssh/id_dsa type -1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/perebor/.ssh/id_dsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/perebor/.ssh/id_ecdsa type -1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/perebor/.ssh/id_ecdsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/perebor/.ssh/id_ed25519 type -1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/perebor/.ssh/id_ed25519-cert type -1
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_7.4
debug1: Remote protocol version 2.0, remote software version OpenSSH_7.2p2 Ubuntu-4ubuntu2.2
debug1: match: OpenSSH_7.2p2 Ubuntu-4ubuntu2.2 pat OpenSSH* compat 0x04000000
debug1: Authenticating to 10.10.10.10:22 as 'ubuntu'
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug1: kex: algorithm: curve25519-sha256@libssh.org
debug1: kex: host key algorithm: ecdsa-sha2-nistp256
debug1: kex: server->client cipher: chacha20-poly1305@openssh.com MAC: <implicit> compression: none
debug1: kex: client->server cipher: chacha20-poly1305@openssh.com MAC: <implicit> compression: none
debug1: expecting SSH2_MSG_KEX_ECDH_REPLY
debug1: Server host key: ecdsa-sha2-nistp256 SHA256:xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
debug1: Host '10.10.10.10' is known and matches the ECDSA host key.
debug1: Found key in /Users/perebor/.ssh/known_hosts:66
debug1: rekey after 134217728 blocks
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug1: SSH2_MSG_NEWKEYS received
debug1: rekey after 134217728 blocks
debug1: SSH2_MSG_EXT_INFO received
debug1: kex_input_ext_info: server-sig-algs=<rsa-sha2-256,rsa-sha2-512>
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug1: Authentications that can continue: publickey
debug1: Next authentication method: publickey
debug1: Offering RSA public key: /Users/perebor/.ssh/id_rsa
debug1: Server accepts key: pkalg rsa-sha2-512 blen 535
debug1: Authentication succeeded (publickey).
Authenticated to 10.10.10.10 ([10.10.10.10]:22).
debug1: channel 0: new [client-session]
debug1: Requesting no-more-sessions@openssh.com
debug1: Entering interactive session.
debug1: pledge: network
debug1: client_input_global_request: rtype hostkeys-00@openssh.com want_reply 0
Welcome to Ubuntu 16.04.3 LTS (GNU/Linux 4.10.0-33-generic x86_64)

 * Documentation:  https://help.ubuntu.com
 * Management:     https://landscape.canonical.com
 * Support:        https://ubuntu.com/advantage

0 packages can be updated.
0 updates are security updates.

完

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