当我像这样输入 sftp 时，它通常会提示我输入密码，因为用户名位于命令中，但对于这台机器，它会再次要求输入用户名。
sftp [email protected]
Username:
再次输入用户名和密码后，就可以正常登录了。什么会导致这种情况发生？
Verbose:(X.X.X.X) is the same IP throughout the log
OpenSSH_8.0p1, OpenSSL 1.1.1k FIPS 25 Mar 2021
debug1: Reading configuration data /root/.ssh/config
debug1: /root/.ssh/config line 1: Applying options for x.x.x.x
debug3: kex names ok: [diffie-hellman-group-exchange-sha1]
debug1: /root/.ssh/config line 3: Applying options for x.x.x.x
debug1: Reading configuration data /etc/ssh/ssh_config
debug3: /etc/ssh/ssh_config line 52: Including file /etc/ssh/ssh_config.d/05-redhat.conf depth 0
debug1: Reading configuration data /etc/ssh/ssh_config.d/05-redhat.conf
debug2: checking match for 'final all' host x.x.x.x originally x.x.x.x
debug3: /etc/ssh/ssh_config.d/05-redhat.conf line 3: not matched 'final'
debug2: match not found
debug3: /etc/ssh/ssh_config.d/05-redhat.conf line 5: Including file /etc/crypto-policies/back-ends/openssh.config depth 1 (parse only)
debug1: Reading configuration data /etc/crypto-policies/back-ends/openssh.config
debug3: gss kex names ok: [gss-curve25519-sha256-,gss-nistp256-sha256-,gss-group14-sha256-,gss-group16-sha512-,gss-gex-sha1-,gss-group14-sha1-]
debug3: kex names ok: [curve25519-sha256,[email protected],ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group14-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1]
debug1: configuration requests final Match pass
debug2: resolve_canonicalize: hostname x.x.x.x is address
debug1: re-parsing configuration
debug1: Reading configuration data /root/.ssh/config
debug1: /root/.ssh/config line 1: Applying options for x.x.x.x
debug3: kex names ok: [diffie-hellman-group-exchange-sha1]
debug1: /root/.ssh/config line 3: Applying options for x.x.x.x
debug1: Reading configuration data /etc/ssh/ssh_config
debug3: /etc/ssh/ssh_config line 52: Including file /etc/ssh/ssh_config.d/05-redhat.conf depth 0
debug1: Reading configuration data /etc/ssh/ssh_config.d/05-redhat.conf
debug2: checking match for 'final all' host x.x.x.x originally x.x.x.x
debug3: /etc/ssh/ssh_config.d/05-redhat.conf line 3: matched 'final'
debug2: match found
debug3: /etc/ssh/ssh_config.d/05-redhat.conf line 5: Including file /etc/crypto-policies/back-ends/openssh.config depth 1
debug1: Reading configuration data /etc/crypto-policies/back-ends/openssh.config
debug3: gss kex names ok: [gss-curve25519-sha256-,gss-nistp256-sha256-,gss-group14-sha256-,gss-group16-sha512-,gss-gex-sha1-,gss-group14-sha1-]
debug3: kex names ok: [curve25519-sha256,[email protected],ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group14-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1]
debug2: ssh_connect_direct
debug1: Connecting to x.x.x.x [x.x.x.x] port 22.
debug1: Connection established.
debug1: identity file /root/.ssh/id_rsa type 0
debug1: identity file /root/.ssh/id_rsa-cert type -1
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: identity file /root/.ssh/id_ed25519 type -1
debug1: identity file /root/.ssh/id_ed25519-cert type -1
debug1: identity file /root/.ssh/id_xmss type -1
debug1: identity file /root/.ssh/id_xmss-cert type -1
debug1: Local version string SSH-2.0-OpenSSH_8.0
debug1: Remote protocol version 2.0, remote software version Priority
debug1: no match: Priority
debug2: fd 3 setting O_NONBLOCK
debug1: Authenticating to x.x.x.x:22 as 'Username'
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-group14-sha256,diffie-hellman-group14-sha1,diffie-hellman-group-exchange-sha1,ext-info-c
debug2: host key algorithms: [email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,ssh-ed25519,rsa-sha2-512,rsa-sha2-256,ssh-rsa,ssh-dss
debug2: ciphers ctos: [email protected],[email protected],aes256-ctr,aes256-cbc,[email protected],aes128-ctr,aes128-cbc
debug2: ciphers stoc: [email protected],[email protected],aes256-ctr,aes256-cbc,[email protected],aes128-ctr,aes128-cbc
debug2: MACs ctos: [email protected],[email protected],[email protected],[email protected],hmac-sha2-256,hmac-sha1,[email protected],hmac-sha2-512
debug2: MACs stoc: [email protected],[email protected],[email protected],[email protected],hmac-sha2-256,hmac-sha1,[email protected],hmac-sha2-512
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-group-exchange-sha1,diffie-hellman-group1-sha1,diffie-hellman-group14-sha1,diffie-hellman-group-exchange-sha256
debug2: host key algorithms: ssh-dss
debug2: ciphers ctos: 3des-cbc,blowfish-cbc,twofish256-cbc,twofish192-cbc,twofish128-cbc,aes256-cbc,aes192-cbc,aes128-cbc,serpent256-cbc,serpent192-cbc,serpent128-cbc,arcfour,idea-cbc,cast128-cbc,none,des-cbc,aes128-ctr,aes192-ctr,aes256-ctr,3des-ctr,blowfish-ctr,twofish128-ctr,twofish192-ctr,twofish256-ctr,serpent128-ctr,serpent192-ctr,serpent256-ctr,idea-ctr,cast128-ctr,arcfour128,arcfour256,aes128-gcm,aes256-gcm,[email protected],[email protected],chacha20-poly1305,[email protected]
debug2: ciphers stoc: 3des-cbc,blowfish-cbc,twofish256-cbc,twofish192-cbc,twofish128-cbc,aes256-cbc,aes192-cbc,aes128-cbc,serpent256-cbc,serpent192-cbc,serpent128-cbc,arcfour,idea-cbc,cast128-cbc,none,des-cbc,aes128-ctr,aes192-ctr,aes256-ctr,3des-ctr,blowfish-ctr,twofish128-ctr,twofish192-ctr,twofish256-ctr,serpent128-ctr,serpent192-ctr,serpent256-ctr,idea-ctr,cast128-ctr,arcfour128,arcfour256,aes128-gcm,aes256-gcm,[email protected],[email protected],chacha20-poly1305,[email protected]
debug2: MACs ctos: hmac-sha1,hmac-sha1-96,hmac-md5,hmac-md5-96,none,hmac-ripemd160,hmac-ripemd,[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],hmac-sha2-256,hmac-sha2-512,aes128-gcm,aes256-gcm,[email protected]
debug2: MACs stoc: hmac-sha1,hmac-sha1-96,hmac-md5,hmac-md5-96,none,hmac-ripemd160,hmac-ripemd,[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],hmac-sha2-256,hmac-sha2-512,aes128-gcm,aes256-gcm,[email protected]
debug2: compression ctos: none,zlib,[email protected]
debug2: compression stoc: none,zlib,[email protected]
debug2: languages ctos:
debug2: languages stoc:
debug2: first_kex_follows 0
debug2: reserved 0
debug1: kex: algorithm: diffie-hellman-group-exchange-sha256
debug1: kex: host key algorithm: ssh-dss
debug1: kex: server->client cipher: [email protected] MAC: <implicit> compression: none
debug1: kex: client->server cipher: [email protected] MAC: <implicit> compression: none
debug1: kex: diffie-hellman-group-exchange-sha256 need=32 dh_need=32
debug1: kex: diffie-hellman-group-exchange-sha256 need=32 dh_need=32
debug3: send packet: type 34
debug1: SSH2_MSG_KEX_DH_GEX_REQUEST(2048<8192<8192) sent
debug3: receive packet: type 31
debug1: got SSH2_MSG_KEX_DH_GEX_GROUP
debug2: bits set: 4118/8192
debug3: send packet: type 32
debug1: SSH2_MSG_KEX_DH_GEX_INIT sent
debug3: receive packet: type 33
debug1: got SSH2_MSG_KEX_DH_GEX_REPLY
debug1: Server host key: ssh-dss SHA256:0A1Ar92Ajwji6j1W3xY3NM4NNrurkbyIUTa8vrj+WLk
debug3: hostkeys_foreach: reading file "/root/.ssh/known_hosts"
debug3: record_hostkey: found key type DSA in file /root/.ssh/known_hosts:13
debug3: load_hostkeys: loaded 1 keys from x.x.x.x
debug1: Host 'x.x.x.x' is known and matches the DSA host key.
debug1: Found key in /root/.ssh/known_hosts:13
debug2: bits set: 4069/8192
debug3: send packet: type 21
debug2: set_newkeys: mode 1
debug1: rekey out 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 in after 4294967296 blocks
debug1: Will attempt key: /root/.ssh/id_rsa RSA SHA256:o+fnPf1DCYESqkGs+QyEVHvrojcf4wE/o9lmXEHQdCY
debug1: Will attempt key: /root/.ssh/id_dsa
debug1: Will attempt key: /root/.ssh/id_ecdsa
debug1: Will attempt key: /root/.ssh/id_ed25519
debug1: Will attempt key: /root/.ssh/id_xmss
debug2: pubkey_prepare: done
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: password,publickey,keyboard-interactive,hostbased
debug3: start over, passed a different list password,publickey,keyboard-interactive,hostbased
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: /root/.ssh/id_rsa RSA SHA256:o+fnPf1DCYESqkGs+QyEVHvrojcf4wE/o9lmXEHQdCY
debug3: send packet: type 50
debug2: we sent a publickey packet, wait for reply
debug3: receive packet: type 51
debug1: Authentications that can continue: password,publickey,keyboard-interactive
debug3: start over, passed a different list password,publickey,keyboard-interactive
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: /root/.ssh/id_dsa
debug3: no such identity: /root/.ssh/id_dsa: No such file or directory
debug1: Trying private key: /root/.ssh/id_ecdsa
debug3: no such identity: /root/.ssh/id_ecdsa: No such file or directory
debug1: Trying private key: /root/.ssh/id_ed25519
debug3: no such identity: /root/.ssh/id_ed25519: No such file or directory
debug1: Trying private key: /root/.ssh/id_xmss
debug3: no such identity: /root/.ssh/id_xmss: No such file or directory
debug2: we did not send a packet, disable method
debug3: authmethod_lookup keyboard-interactive
debug3: remaining preferred: password
debug3: authmethod_is_enabled keyboard-interactive
debug1: Next authentication method: keyboard-interactive
debug2: userauth_kbdint
debug3: send packet: type 50
debug2: we sent a keyboard-interactive packet, wait for reply
debug3: receive packet: type 60
debug2: input_userauth_info_req
Please enter your username and password
debug2: input_userauth_info_req: num_prompts 2
答案1
您正在连接到一些不寻常/非标准的 SSH 服务器。
服务器似乎忽略了作为标准 SSH 身份验证一部分发送的用户名，并发送自己的键盘交互提示以获取凭据。虽然键盘交互提示通常用于密码提示（请参阅“密码”和“键盘交互”有什么区别？），通常不使用（而且有点错误）来提示（再次）输入用户名。
OpenSSH 客户端永远不会尝试自动应答任何键盘交互提示。我根本不知道有哪个 SSH 客户端能够自动应答键盘交互的用户名提示——因为服务器这样做是出乎意料的。