我成功地使用了准确的私钥 2 周来通过 ssh 进入我的 EC2 实例。 我今天试过了（我这边没有任何改变），但它不再工作了......
完整的详细日志如下：（将所有出现的 ip 替换为 $IP） 事实：
- ip 已启动并正在运行，网络服务器正在返回正常的页面服务，因此实例不会停止
- 我在过去 2 周内没有进行任何手动更改导致此问题
- 在 2 个月前，我通过在 ec2 实例中添加已知密钥和当前密钥来更改 ssh 密钥。我在
.ssh/authorized_keys将它添加到用户 ubuntu。它正常工作了 3 周，此后实例未重新启动/停止
root@vagrant:/srv# ssh -vvv -i build/certs/ec2-ws.pem ubuntu@$IP
OpenSSH_8.2p1 Ubuntu-4ubuntu0.1,OpenSSL 1.1.1f 31 Mar 2020
debug1: Reading configuration data /root/.ssh/config
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 19: include /etc/ssh/ssh_config.d/*.conf matched no files
debug1: /etc/ssh/ssh_config line 21: Applying options for *
debug2: resolve_canonicalize: hostname $IP is address
debug2: ssh_connect_direct
debug1: Connecting to $IP [$IP] port 22.
debug1: Connection established.
debug1: identity file build/certs/ec2-ws.pem type -1
debug1: identity file build/certs/ec2-ws.pem-cert type -1
debug1: Local version string SSH-2.0-OpenSSH_8.2p1 Ubuntu-4ubuntu0.1
debug1: Remote protocol version 2.0,remote software version OpenSSH_8.2p1 Ubuntu-4ubuntu0.2
debug1: match: OpenSSH_8.2p1 Ubuntu-4ubuntu0.2 pat OpenSSH* compat 0x04000000
debug2: fd 3 setting O_NONBLOCK
debug1: Authenticating to $IP:22 as 'ubuntu'
debug3: hostkeys_foreach: reading file "/root/.ssh/known_hosts"
debug3: record_hostkey: found key type ECDSA in file /root/.ssh/known_hosts:3
debug3: load_hostkeys: loaded 1 keys from $IP
debug3: order_hostkeyalgs: prefer hostkeyalgs: ecdsa-sha2-nistp256-cert-v01@openssh.com,ecdsa-sha2-nistp384-cert-v01@openssh.com,ecdsa-sha2-nistp521-cert-v01@openssh.com,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521
debug3: send packet: type 20
debug1: SSH2_MSG_KEXINIT sent
debug3: receive packet: type 20
debug1: SSH2_MSG_KEXINIT received
debug2: local client KEXINIT proposal
debug2: KEX algorithms: curve25519-sha256,curve25519-sha256@libssh.org,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512,diffie-hellman-group14-sha256,ext-info-c
debug2: host key algorithms: ecdsa-sha2-nistp256-cert-v01@openssh.com,ecdsa-sha2-nistp521,sk-ecdsa-sha2-nistp256-cert-v01@openssh.com,ssh-ed25519-cert-v01@openssh.com,sk-ssh-ed25519-cert-v01@openssh.com,rsa-sha2-512-cert-v01@openssh.com,rsa-sha2-256-cert-v01@openssh.com,ssh-rsa-cert-v01@openssh.com,sk-ecdsa-sha2-nistp256@openssh.com,ssh-ed25519,sk-ssh-ed25519@openssh.com,rsa-sha2-512,rsa-sha2-256,ssh-rsa
debug2: ciphers ctos: chacha20-poly1305@openssh.com,aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm@openssh.com,aes256-gcm@openssh.com
debug2: ciphers stoc: chacha20-poly1305@openssh.com,aes256-gcm@openssh.com
debug2: MACs ctos: umac-64-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha1-etm@openssh.com,umac-64@openssh.com,umac-128@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1
debug2: MACs stoc: umac-64-etm@openssh.com,hmac-sha1
debug2: compression ctos: none,zlib@openssh.com,zlib
debug2: compression stoc: none,zlib
debug2: languages ctos:
debug2: languages stoc:
debug2: first_kex_follows 0
debug2: reserved 0
debug2: peer server KEXINIT proposal
debug2: KEX algorithms: curve25519-sha256,diffie-hellman-group14-sha256
debug2: host key algorithms: rsa-sha2-512,ssh-rsa,ssh-ed25519
debug2: ciphers ctos: chacha20-poly1305@openssh.com,zlib@openssh.com
debug2: compression stoc: none,zlib@openssh.com
debug2: languages ctos:
debug2: languages stoc:
debug2: first_kex_follows 0
debug2: reserved 0
debug1: kex: algorithm: curve25519-sha256
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
debug3: send packet: type 30
debug1: expecting SSH2_MSG_KEX_ECDH_REPLY
debug3: receive packet: type 31
debug1: Server host key: ecdsa-sha2-nistp256 SHA256:VIEKD2Ga7/nmdDtnknntuJuMRB1iOIjxykMu0RBNkJ4
debug3: hostkeys_foreach: reading file "/root/.ssh/known_hosts"
debug3: record_hostkey: found key type ECDSA in file /root/.ssh/known_hosts:3
debug3: load_hostkeys: loaded 1 keys from $IP
debug1: Host '$IP' is known and matches the ECDSA host key.
debug1: Found key in /root/.ssh/known_hosts:3
debug3: send packet: type 21
debug2: set_newkeys: mode 1
debug1: rekey out after 134217728 blocks
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug3: receive packet: type 21
debug1: SSH2_MSG_NEWKEYS received
debug2: set_newkeys: mode 0
debug1: rekey in after 134217728 blocks
debug1: pubkey_prepare: ssh_get_authentication_socket: No such file or directory
debug1: Will attempt key: build/certs/ec2-ws.pem explicit
debug2: pubkey_prepare: done
debug3: send packet: type 5
debug3: receive packet: type 7
debug1: SSH2_MSG_EXT_INFO received
debug1: kex_input_ext_info: server-sig-algs=<ssh-ed25519,ssh-dss,sk-ecdsa-sha2-nistp256@openssh.com>
debug3: receive packet: type 6
debug2: service_accept: ssh-userauth
debug1: SSH2_MSG_SERVICE_accEPT received
debug3: send packet: type 50
debug3: receive packet: type 51
debug1: Authentications that can continue: publickey
debug3: start over,passed a different list publickey
debug3: preferred 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: build/certs/ec2-ws.pem
debug3: sign_and_send_pubkey: RSA SHA256:vcgi2zByy4gWafWHN6eDfe53A0oQ/ecPwKXMmCNwiJ8
debug3: sign_and_send_pubkey: signing using rsa-sha2-512 SHA256:vcgi2zByy4gWafWHN6eDfe53A0oQ/ecPwKXMmCNwiJ8
debug3: send packet: type 50
debug2: we sent a publickey packet,wait for reply
debug3: receive packet: type 51
debug1: Authentications that can continue: publickey
debug2: we did not send a packet,disable method
debug1: No more authentication methods to try.