iOS/iPadOS上iSH应用（Proot Alpine Linux）可SSH连接但无法SFTP连接的问题求助

大家好，我遇到一个奇怪的问题：我在iPadOS上用iSH应用，它本质是个prooted的Alpine Linux，运行起来几乎没什么毛病——我能从任意macOS或Linux终端正常SSH连接到这个iOS设备上，体验有点像安卓上的Termux，本身是支持SSH和SFTP请求的。

但麻烦的是，当我用支持SSH/SFTP的文件浏览器（比如Linux下的Thunar或者macOS的Forklift）尝试连接时，却总是连接失败。不管我用SSH密钥认证还是密码认证，结果都一样。我记得之前在Linux服务器上遇到过类似的SFTP连接问题，但完全忘了当时是怎么解决的了。

我用sftp的verbose模式跑了一遍，输出如下：

armemac.local:~/scratch % sftp -v -P 22 root@192.168.0.11

OpenSSH_9.0p1, LibreSSL 3.3.6

debug1: Reading configuration data /Users/me/.ssh/config

debug1: Reading configuration data /etc/ssh/ssh_config

debug1: /etc/ssh/ssh_config line 21: include /etc/ssh/ssh_config.d/* matched no files

debug1: /etc/ssh/ssh_config line 54: Applying options for *

debug1: Authenticator provider $SSH_SK_PROVIDER did not resolve; disabling

debug1: Connecting to 192.168.0.11 [192.168.0.11] port 22.

debug1: Connection established.

debug1: identity file /Users/me/.ssh/id_rsa type 0

debug1: identity file /Users/me/.ssh/id_rsa-cert type -1

debug1: identity file /Users/me/.ssh/id_ecdsa type -1

debug1: identity file /Users/me/.ssh/id_ecdsa-cert type -1

debug1: identity file /Users/me/.ssh/id_ecdsa_sk type -1

debug1: identity file /Users/me/.ssh/id_ecdsa_sk-cert type -1

debug1: identity file /Users/me/.ssh/id_ed25519 type -1

debug1: identity file /Users/me/.ssh/id_ed25519-cert type -1

debug1: identity file /Users/me/.ssh/id_ed25519_sk type -1

debug1: identity file /Users/me/.ssh/id_ed25519_sk-cert type -1

debug1: identity file /Users/me/.ssh/id_xmss type -1

debug1: identity file /Users/me/.ssh/id_xmss-cert type -1

debug1: identity file /Users/me/.ssh/id_dsa type 1

debug1: identity file /Users/me/.ssh/id_dsa-cert type -1

debug1: Local version string SSH-2.0-OpenSSH_9.0

debug1: Remote protocol version 2.0, remote software version OpenSSH_8.6

debug1: compat_banner: match: OpenSSH_8.6 pat OpenSSH* compat 0x04000000

debug1: Authenticating to 192.168.0.11:22 as 'root'

debug1: load_hostkeys: fopen /Users/me/.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

debug1: kex: algorithm: curve25519-sha256

debug1: kex: host key algorithm: ssh-ed25519

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: SSH2_MSG_KEX_ECDH_REPLY received

debug1: Server host key: ssh-ed25519 SHA256:DMet4OKiC2qzSCISNQrElbikS35uALIRhmM1BK6FII0

debug1: load_hostkeys: fopen /Users/me/.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 '192.168.0.11' is known and matches the ED25519 host key.

debug1: Found key in /Users/me/.ssh/known_hosts:159

debug1: rekey out after 134217728 blocks

debug1: SSH2_MSG_NEWKEYS sent

debug1: expecting SSH2_MSG_NEWKEYS

debug1: SSH2_MSG_NEWKEYS received

debug1: rekey in after 134217728 blocks

debug1: get_agent_identities: agent returned 1 keys

debug1: Skipping ssh-dss key /Users/me/.ssh/id_dsa - corresponding algo not in PubkeyAcceptedAlgorithms

debug1: Will attempt key: ecdsa-sha2-nistp256 ECDSA SHA256:xn2CTvLgP6mlJ0+iZ52fvzUS3i5bxMLNvfMfBd9Q4aw agent

debug1: Will attempt key: /Users/me/.ssh/id_rsa RSA SHA256:Mh8uuwZwf0zVhPGPmZ/i7SVHlikZmAleGnj9kphNMts

debug1: Will attempt key: /Users/me/.ssh/id_ecdsa

debug1: Will attempt key: /Users/me/.ssh/id_ecdsa_sk

debug1: Will attempt key: /Users/me/.ssh/id_ed25519

debug1: Will attempt key: /Users/me/.ssh/id_ed25519_sk

debug1: Will attempt key: /Users/me/.ssh/id_xmss

debug1: SSH2_MSG_EXT_INFO received

debug1: kex_input_ext_info: server-sig-algs=<ssh-ed25519,sk-ssh-ed25519@openssh.com,ssh-rsa,rsa-sha2-256,rsa-sha2-512,ssh-dss,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,sk-ecdsa-sha2-nistp256@openssh.com,webauthn-sk-ecdsa-sha2-nistp256@openssh.com>

debug1: SSH2_MSG_SERVICE_ACCEPT received

debug1: Authentications that can continue: publickey,password,keyboard-interactive

debug1: Next authentication method: publickey

debug1: Offering public key: ecdsa-sha2-nistp256 ECDSA SHA256:xn2CTvLgP6mlJ0+iZ52fvzUS3i5bxMLNvfMfBd9Q4aw agent

debug1: Server accepts key: ecdsa-sha2-nistp256 ECDSA SHA256:xn2CTvLgP6mlJ0+iZ52fvzUS3i5bxMLNvfMfBd9Q4aw agent

Authenticated to 192.168.0.11 ([192.168.0.11]:22) using "publickey".

debug1: channel 0: new [client-session]

debug1: Requesting no-more-sessions@openssh.com

debug1: Entering interactive session.

debug1: pledge: filesystem

debug1: client_input_global_request: rtype hostkeys-00@openssh.com want_reply 0

debug1: client_input_hostkeys: searching /Users/me/.ssh/known_hosts for 192.168.0.11 / (none)

debug1: client_input_hostkeys: searching /Users/me/.ssh/known_hosts2 for 192.168.0.11 / (none)

debug1: client_input_hostkeys: hostkeys file /Users/me/.ssh/known_hosts2 does not exist

debug1: Remote: /root/.ssh/authorized_keys:1: key options: agent-forwarding port-forwarding pty user-rc x11-forwarding

debug1: Remote: /root/.ssh/authorized_keys:1: key options: agent-forwarding port-forwarding pty user-rc x11-forwarding

debug1: Sending environment.

debug1: channel 0: setting env LC_CTYPE = "UTF-8"

debug1: Sending subsystem: sftp

debug1: client_global_hostkeys_private_confirm: server used untrusted RSA signature algorithm ssh-rsa for key 0, disregarding

Learned new hostkey: ECDSA SHA256:5qJ/Mqnn7rX9cHd24TxMmwALdOYCFYZOuwXMDXToXJk

Adding new key for 192.168.0.11 to /Users/me/.ssh/known_hosts: ecdsa-sha2-nistp256 SHA256:5qJ/Mqnn7rX9cHd24TxMmwALdOYCFYZOuwXMDXToXJk

debug1: update_known_hosts: known hosts file /Users/me/.ssh/known_hosts2 does not exist

debug1: client_input_channel_req: channel 0 rtype exit-status reply 0

debug1: client_input_channel_req: channel 0 rtype eow@openssh.com reply 0

debug1: channel 0: free: client-session, nchannels 1

Transferred: sent 2772, received 3336 bytes, in 0.9 seconds

Bytes per second: sent 3089.3, received 3717.8

debug1: Exit status 255

我尝试在~/.ssh/config里添加了以下配置：

Host 192.168.0.11
    UpdateHostKeys no

但这只是去掉了那条debug1: client_global_hostkeys_private_confirm: server used untrusted RSA signature algorithm ssh-rsa for key 0, disregarding的提示信息，SFTP连接失败的问题依然存在。

另外我还有个疑问：为什么sftp会一直查找known_hosts2文件？而且从Debian Linux客户端连接时，也会出现类似的RSA密钥相关提示。

有没有朋友遇到过类似的问题，或者知道该怎么解决这个SFTP连接失败的问题？

备注：内容来源于stack exchange，提问作者user513667