ubuntu-2204 gerrit ssh 报错Permission denied (publickey).分析及解决

ubuntu-2204 gerrit/git ssh 报错Permission denied (publickey).分析及解决

使用repo init/sync下载代码时遇到报错: Permission denied (publickey).

分析排查步骤

通过以下步骤排查

以下user及10.100.1.115为化名

$ ssh -p 29418 [email protected]

The authenticity of host '[10.100.1.115]:29418 ([10.100.1.115]:29418)' can't be established.
ED25519 key fingerprint is SHA256:YmW8pF9ZuvIBcT6qWr5Q72zTP7RBVoGcovSKth6uFWo.
This key is not known by any other names
Are you sure you want to continue connecting (yes/no/[fingerprint])? yes
Warning: Permanently added '[10.100.1.115]:29418' (ED25519) to the list of known hosts.
[email protected]: Permission denied (publickey).

查看详细信息
$ ssh -vv -p 29418 [email protected]

OpenSSH_8.9p1 Ubuntu-3, OpenSSL 3.0.2 15 Mar 2022
debug1: Reading configuration data /home/user/.ssh/config
debug1: /home/user/.ssh/config line 1: Applying options for *
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 10.100.1.115 is address
debug1: Connecting to 10.100.1.115 [10.100.1.115] port 29418.
debug1: Connection established.
debug1: identity file /home/user/.ssh/id_rsa type 0
debug1: identity file /home/user/.ssh/id_rsa-cert type -1
debug1: identity file /home/user/.ssh/id_ecdsa type -1
debug1: identity file /home/user/.ssh/id_ecdsa-cert type -1
debug1: identity file /home/user/.ssh/id_ecdsa_sk type -1
debug1: identity file /home/user/.ssh/id_ecdsa_sk-cert type -1
debug1: identity file /home/user/.ssh/id_ed25519 type -1
debug1: identity file /home/user/.ssh/id_ed25519-cert type -1
debug1: identity file /home/user/.ssh/id_ed25519_sk type -1
debug1: identity file /home/user/.ssh/id_ed25519_sk-cert type -1
debug1: identity file /home/user/.ssh/id_xmss type -1
debug1: identity file /home/user/.ssh/id_xmss-cert type -1
debug1: identity file /home/user/.ssh/id_dsa type -1
debug1: identity file /home/user/.ssh/id_dsa-cert type -1
debug1: Local version string SSH-2.0-OpenSSH_8.9p1 Ubuntu-3
debug1: Remote protocol version 2.0, remote software version GerritCodeReview_3.2.7 (APACHE-SSHD-2.4.0)
debug1: compat_banner: no match: GerritCodeReview_3.2.7 (APACHE-SSHD-2.4.0)
debug2: fd 3 setting O_NONBLOCK
debug1: Authenticating to 10.100.1.115:29418 as 'user'
debug1: load_hostkeys: fopen /home/user/.ssh/known_hosts2: No such file or directory
debug1: load_hostkeys: fopen /etc/ssh/ssh_known_hosts: No such file or directory
debug1: load_hostkeys: fopen /etc/ssh/ssh_known_hosts2: No such file or directory
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug2: local client KEXINIT proposal
debug2: KEX algorithms: curve25519-sha256,[email protected],ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,[email protected],diffie-hellman-group-exchange-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512,diffie-hellman-group14-sha256,ext-info-c
debug2: host key algorithms: [email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],ssh-ed25519,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,[email protected],[email protected],rsa-sha2-512,rsa-sha2-256
debug2: ciphers ctos: [email protected],aes128-ctr,aes192-ctr,aes256-ctr,[email protected],[email protected]
debug2: ciphers stoc: [email protected],aes128-ctr,aes192-ctr,aes256-ctr,[email protected],[email protected]
debug2: MACs ctos: [email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],hmac-sha2-256,hmac-sha2-512,hmac-sha1
debug2: MACs stoc: [email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],hmac-sha2-256,hmac-sha2-512,hmac-sha1
debug2: compression ctos: none,[email protected],zlib
debug2: compression stoc: none,[email protected],zlib
debug2: languages ctos: 
debug2: languages stoc: 
debug2: first_kex_follows 0 
debug2: reserved 0 
debug2: peer server KEXINIT proposal
debug2: KEX algorithms: ecdh-sha2-nistp521,ecdh-sha2-nistp384,ecdh-sha2-nistp256,diffie-hellman-group-exchange-sha256,diffie-hellman-group-exchange-sha1,diffie-hellman-group18-sha512,diffie-hellman-group17-sha512,diffie-hellman-group16-sha512,diffie-hellman-group15-sha512,diffie-hellman-group14-sha256,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1
debug2: host key algorithms: ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,ssh-ed25519,rsa-sha2-512,rsa-sha2-256,ssh-rsa
debug2: ciphers ctos: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,aes192-cbc,aes256-cbc
debug2: ciphers stoc: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,aes192-cbc,aes256-cbc
debug2: MACs ctos: [email protected],[email protected],[email protected],hmac-sha2-256,hmac-sha2-512,hmac-sha1,hmac-md5,hmac-sha1-96,hmac-md5-96
debug2: MACs stoc: [email protected],[email protected],[email protected],hmac-sha2-256,hmac-sha2-512,hmac-sha1,hmac-md5,hmac-sha1-96,hmac-md5-96
debug2: compression ctos: none
debug2: compression stoc: none
debug2: languages ctos: 
debug2: languages stoc: 
debug2: first_kex_follows 0 
debug2: reserved 0 
debug1: kex: algorithm: ecdh-sha2-nistp256
debug1: kex: host key algorithm: ssh-ed25519
debug1: kex: server->client cipher: aes128-ctr MAC: [email protected] compression: none
debug1: kex: client->server cipher: aes128-ctr MAC: [email protected] compression: none
debug1: expecting SSH2_MSG_KEX_ECDH_REPLY
debug1: SSH2_MSG_KEX_ECDH_REPLY received
debug1: Server host key: ssh-ed25519 SHA256:YmW8pF9ZuvIBcT6qWr5Q72zTP7RBVoGcovSKth6uFWo
debug1: load_hostkeys: fopen /home/user/.ssh/known_hosts2: No such file or directory
debug1: load_hostkeys: fopen /etc/ssh/ssh_known_hosts: No such file or directory
debug1: load_hostkeys: fopen /etc/ssh/ssh_known_hosts2: No such file or directory
debug1: Host '[10.100.1.115]:29418' is known and matches the ED25519 host key.
debug1: Found key in /home/user/.ssh/known_hosts:1
debug2: ssh_set_newkeys: mode 1
debug1: rekey out after 4294967296 blocks
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug1: SSH2_MSG_NEWKEYS received
debug2: ssh_set_newkeys: mode 0
debug1: rekey in after 4294967296 blocks
debug1: get_agent_identities: bound agent to hostkey
debug1: get_agent_identities: agent returned 1 keys
debug1: Will attempt key: /home/user/.ssh/id_rsa RSA SHA256:bansqueqJ/in2VZCOhLH8qQbALzUhWiHySt3gePFYds agent
debug1: Will attempt key: /home/user/.ssh/id_ecdsa 
debug1: Will attempt key: /home/user/.ssh/id_ecdsa_sk 
debug1: Will attempt key: /home/user/.ssh/id_ed25519 
debug1: Will attempt key: /home/user/.ssh/id_ed25519_sk 
debug1: Will attempt key: /home/user/.ssh/id_xmss 
debug1: Will attempt key: /home/user/.ssh/id_dsa 
debug2: pubkey_prepare: done
debug2: service_accept: ssh-userauth
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug1: Authentications that can continue: publickey
debug1: Next authentication method: publickey
debug1: Offering public key: /home/user/.ssh/id_rsa RSA SHA256:bansqueqJ/in2VZCOhLH8qQbALzUhWiHySt3gePFYds agent
debug1: send_pubkey_test: no mutual signature algorithm
debug1: Trying private key: /home/user/.ssh/id_ecdsa
debug1: Trying private key: /home/user/.ssh/id_ecdsa_sk
debug1: Trying private key: /home/user/.ssh/id_ed25519
debug1: Trying private key: /home/user/.ssh/id_ed25519_sk
debug1: Trying private key: /home/user/.ssh/id_xmss
debug1: Trying private key: /home/user/.ssh/id_dsa
debug2: we did not send a packet, disable method
debug1: No more authentication methods to try.
[email protected]: Permission denied (publickey).

通过以上详细信息可以看到以下几个关键点

• OpenSSH版本为 OpenSSH_8.9p1
• 失败的具体原因为

debug1: Next authentication method: publickey
debug1: Offering public key: /home/user/.ssh/id_rsa RSA SHA256:bansqueqJ/in2VZCOhLH8qQbALzUhWiHySt3gePFYds agent
debug1: send_pubkey_test: no mutual signature algorithm
debug1: Trying private key: /home/user/.ssh/id_ecdsa
debug1: Trying private key: /home/user/.ssh/id_ecdsa_sk
debug1: Trying private key: /home/user/.ssh/id_ed25519
debug1: Trying private key: /home/user/.ssh/id_ed25519_sk
debug1: Trying private key: /home/user/.ssh/id_xmss
debug1: Trying private key: /home/user/.ssh/id_dsa
debug2: we did not send a packet, disable method
debug1: No more authentication methods to try.
[email protected]: Permission denied (publickey).

• 验证publickey时，本地提供了私钥/home/user/.ssh/id_rsa，但是no mutual signature algorithm 无互签名算法，尝试ed25529等算法但是没有匹配的认证方式。
• 解决办法是提供ecdsa,ed25519,dsa等算法的公钥和私钥对。

深层次原因及解决方法

OpenSSH 8.8 考虑到cryptographically broken,开始禁用了使用SHA-1哈希算法的RSA签名算法。
这是一个客户端限制。我们必须提供能被OpenSSH 8.8认可的密钥类型，比如 OpenSSH 推荐的Ed25519。

配置方法如下：

1. 生成ed25519密钥
   ssh-keygen -t ed25519 -C "[email protected]"

2. 将.ssh/id_ed25519.pub的文本添加到gerrit或git用户配置的SSH keys中

3. 可以在$HOME/.ssh/config配置文件中指定认证选项，明确指定认证文件(不是必须的)
   比如：

Host your.gerrit.host
IdentityFile ~/.ssh/id_ed25519

4. 或者在$HOME/.ssh/config配置文件中指定客户端接受RSA密钥（不推荐）

PubkeyAcceptedKeyTypes +ssh-rsa