使用 Luci 网页界面恢复配置备份后，ssh 公钥认证停止工作：
$ ssh [email protected] -i ~/.ssh/id_rsa
[email protected]: Permission denied (publickey)
检查了 dropbear：
root@OpenWrt:/etc/dropbear# ls -l
-rw------- 1 501 20 724 Apr 29 09:07 authorized_keys
/etc/dropbear/authorized_keys包含正确的id_rsa.pub钥匙。
Luci 也证实了这一点。有什么不对吗？
$ ssh [email protected] -i ~/.ssh/id_rsa -vvvv
OpenSSH_7.6p1, LibreSSL 2.6.2
debug1: Reading configuration data /Users/drew/.ssh/config
debug1: /Users/drew/.ssh/config line 1: Applying options for *
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 48: Applying options for *
debug2: ssh_connect_direct: needpriv 0
debug1: Connecting to 192.168.1.254 port 22.
debug1: Connection established.
debug1: identity file /Users/drew/.ssh/id_rsa type 0
debug1: key_load_public: No such file or directory
debug1: identity file /Users/drew/.ssh/id_rsa-cert type -1
debug1: Local version string SSH-2.0-OpenSSH_7.6
debug1: Remote protocol version 2.0, remote software version dropbear_2015.67
debug1: no match: dropbear_2015.67
debug3: fd 5 is O_NONBLOCK
debug1: Authenticating to 192.168.1.254:22 as 'root'
debug3: hostkeys_foreach: reading file "/Users/drew/.ssh/known_hosts"
debug3: record_hostkey: found key type RSA in file /Users/drew/.ssh/known_hosts:57
debug3: load_hostkeys: loaded 1 keys from 192.168.1.254
debug3: order_hostkeyalgs: prefer hostkeyalgs: [email protected],rsa-sha2-512,rsa-sha2-256,ssh-rsa
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,[email protected],ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha256,diffie-hellman-group14-sha1,ext-info-c
debug2: host key algorithms: [email protected],rsa-sha2-512,rsa-sha2-256,ssh-rsa,[email protected],[email protected],[email protected],[email protected],ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,ssh-ed25519
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: diffie-hellman-group14-sha1,diffie-hellman-group1-sha1,[email protected]
debug2: host key algorithms: ssh-rsa,ssh-dss
debug2: ciphers ctos: aes128-ctr,aes256-ctr,aes128-cbc,aes256-cbc,3des-ctr,3des-cbc
debug2: ciphers stoc: aes128-ctr,aes256-ctr,aes128-cbc,aes256-cbc,3des-ctr,3des-cbc
debug2: MACs ctos: hmac-sha1,hmac-md5
debug2: MACs stoc: hmac-sha1,hmac-md5
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: diffie-hellman-group14-sha1
debug1: kex: host key algorithm: ssh-rsa
debug1: kex: server->client cipher: aes128-ctr MAC: hmac-sha1 compression: none
debug1: kex: client->server cipher: aes128-ctr MAC: hmac-sha1 compression: none
debug1: sending SSH2_MSG_KEXDH_INIT
debug2: bits set: 1001/2048
debug3: send packet: type 30
debug1: expecting SSH2_MSG_KEXDH_REPLY
debug3: receive packet: type 31
debug1: Server host key: ssh-rsa SHA256:MGw2pwNSJ41mmcBheN3x+BimgVePcLDr15ynkP49L9I
debug3: hostkeys_foreach: reading file "/Users/drew/.ssh/known_hosts"
debug3: record_hostkey: found key type RSA in file /Users/drew/.ssh/known_hosts:57
debug3: load_hostkeys: loaded 1 keys from 192.168.1.254
debug1: Host '192.168.1.254' is known and matches the RSA host key.
debug1: Found key in /Users/drew/.ssh/known_hosts:57
debug2: bits set: 1025/2048
debug3: send packet: type 21
debug2: set_newkeys: mode 1
debug1: rekey after 4294967296 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 after 4294967296 blocks
debug2: key: /Users/drew/.ssh/id_rsa (0x7fc70eb01490), explicit, agent
debug2: key: (0x7fc70e903480), agent
debug2: key: (0x7fc70e9046e0), agent
debug3: send packet: type 5
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: Offering public key: RSA SHA256:NWHiMGnH1Sz8K/cLRV9x493V6B6P8+oat6xtwFViZl4 /Users/drew/.ssh/id_rsa
debug3: send_pubkey_test
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
debug1: Offering public key: RSA SHA256:OLw0tzPx2/CQeq3PzmwR3UdCK0RJuy2t7frV1WyX7fk
debug3: send_pubkey_test
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
debug1: Offering public key: RSA SHA256:8Jahyt/2O/nfBJYtKQuSkwPxg/Ol9ZJcH60hOneKKLQ
debug3: send_pubkey_test
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.
[email protected]: Permission denied (publickey).
答案1
好的，我是如何想到的：
使用密码验证 ssh 进入 OpenWRT，运行
logread |grep dropbear
...
Sun Apr 29 10:23:49 2018 authpriv.info dropbear[8716]: Child connection from 192.168.1.10:62572
Sun Apr 29 10:23:50 2018 authpriv.info dropbear[8716]: /etc/dropbear must be owned by user or root, and not writable by others
Sun Apr 29 10:23:50 2018 authpriv.info dropbear[8716]: Exit before auth (user 'root', 0 fails): Exited normally
...
由于某种原因，/etc/dropbear 的所有权被破坏了。所以我
chown -R root:root /etc/dropbear
解决了所有问题