Server refused to allocate pty => error cygwin putty.exe murugesandins@127.0.0.1
 

I am not able to login using putty.exe to
murugesandins@127.0.0.1
It is reporting following error:
Server refused to allocate pty
Using bash.exe at command prompt:
=========
murugesandins@127.0.0.1 /home/murugesandins [ 0 ]
$ /usr/bin/ssh murugesandins@127.0.0.1
PTY allocation request failed on channel 0
murugesandins@127.0.0.1 OS Microsoft Windows 11 Single Language, 64-bit (build 22631)
Last logon Tue 16-Apr-2024 03:33 PM
/home/murugesandins
Connection to 127.0.0.1 closed.
===============
I faced this issue 3 weeks ago
Re-installed sshd
and daily restart for more than 10 days it resolved
How can I resolve at localhost?
a)
$ grep TTY /etc/sshd_config
#PermitTTY yes
not working after restarting system and sshd service
b)
$ grep TTY /etc/sshd_config
PermitTTY yes
not working after restarting system and sshd service


$ grep -v "^$|#" /etc/sshd_config
Port 22
ListenAddress 127.0.0.1
AuthorizedKeysFile .ssh/authorized_keys
Subsystem sftp /usr/sbin/sftp-server
$ /usr/bin/ls -d ~/.ssh/authorized_keys
/home/murugesandins/.ssh/authorized_keys
I have tried with and without .ssh (including sc stop sc start sshd service and re-starting windows 11)
it is of no use.

I have tried using following sshd versions(which is of no use)
OpenSSH_9.5p1, OpenSSL 3.0.13 30 Jan 2024
OpenSSH_9.6p1, OpenSSL 3.0.13 30 Jan 2024
OpenSSH_9.7p1, OpenSSL 3.0.13 30 Jan 2024

$ openssl.exe version
OpenSSL 3.0.13 30 Jan 2024 (Library: OpenSSL 3.0.13 30 Jan 2024)

#!/bin/bash
echo any shell script using automation at cygwin
I have tried following steps to resolve this issue(but not yet resolved)
1) sc stop cygwin sshd service
2) sc delete cygwin sshd service
3) taskill /f /im bash.exe
to kill automation alert using notepad.exe to remove or add battery alert at laptop if reaching 25% or 98%
4) sc stop exim
and verifiy that startup type is manual
5) I do not have any sendmail service
6) move cygwin directory to cygwin_backup10
7) setup-x86_64.exe --no-admin
download and install openssh at new cygwin directory
include bc.exe and vim.exe during installations
8) move openssl.exe which I have compiled earlier to /usr/bin/ directory to resolve
openssl speed -multi 900000000
bug
I have tested all these steps without replacing existing openssl.exe file.
9) install cygwin sshd service
10)
relogin using putty.exe
which is reporting same error:
Server refused to allocate pty
11)
same error if using
cmd.exe => bash.exe => ssh murugesandins@127.0.0.1
PTY allocation request failed on channel 0

Initially using ssh.exe inside cmd.exe was having following error:
Ignored authorized keys: bad ownership or modes for directory /home/murugesandins
chmod 700 ~/ ~/.ssh
resolved "Ignored authorized keys: bad ownership or modes for directory" error and not:
Server refused to allocate pty
error

a)
Removed /usr/bin/[.exe
b)
Replaced /usr/bin/clear.exe using:
#!/bin/bash
echo -ne "\033[H\033[J"

Hi LQ,

After reboot and relogin at:
Thu 18-Apr-2024 12:12 PM
putty.exe is working fine.
Hence I am making this issue as resolved.
If any person came to know to resolve this feature without reinstall/relogin they can share the same here in future.