ssh does work, but sftp not working

This is a really nice app, much like Termux in Android.

But there is one flaw: sftp in an SSH file browser does not work. Probably a 'standard' Linux/SSH issue.

I connected using Forklift on macOS which resulted in an error (screenshot)

.

I changed sshd-config on the iSH server with the help of searching on this issue on internet by adding `PubkeyAuthentication yes` and changing:
```
# override default of no subsystems
#Subsystem sftp /usr/lib/ssh/sftp-server
Subsystem sftp internal-sftp
```
but to no avail. Obviously I restarted iSH by closing and reopening it on the iPad itself by pressing Ctrl+D and then starting again which automatically starts sshd as I can immediately ssh into iSH again from my Mac.

When I run sftp in verbose mode then the result is:
```
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: compression: none
debug1: kex: client->server cipher: chacha20-poly1305@openssh.com MAC: 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=
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
```
Adding to `~/.ssh/config`
```
Host 192.168.0.11
UpdateHostKeys no
```
does not help, it only leaves out the message `debug1: client_global_hostkeys_private_confirm: server used untrusted RSA signature algorithm ssh-rsa for key 0, disregarding` .

And why does it ask for known_hosts2 ?

iPadOS version 16.4

From a Debian Linux client a similar RSA key message appears.

Start by reproducing the SFTP connection with the verbose `sftp -v -P 22 root@192.168.0.11` command and review the `sshd-config` Subsystem settings described in the report. Compare the SSH and SFTP session behavior, including the reported exit status 255; done means identifying the cause and making SFTP connections work from the reported clients.

Written by the indexing model from the issue text.