OpenSSH_8.3p1, OpenSSL 1.1.1f 31 Mar 2020

[Brian Inglis]

On 2020-09-15 11:00, Everett, Tom (Nokia - US/Westford) via Cygwin wrote:
> I have tried to add kex to config files but I am still unable to get this to work. It was working at one point but I did not back it up or write instructions because I thought I would never have to touch it again, until I did 😊
> 
> Need help establishing the recipe again. Any help would be appreciated.
> 
> 
> $ cygcheck -c Cygwin
> Cygwin Package Information
> Package              Version        Status
> cygwin               3.1.7-1        OK
> 
> 
> SSH Results:
> 
> debug1: Local version string SSH-2.0-OpenSSH_8.3
> debug1: Remote protocol version 2.0, remote software version LiteSSH
> debug1: no match: LiteSSH
> …
> …
> debug1: kex: algorithm: (no match)
> Unable to negotiate with 10.0.3.6 port 22: no matching key exchange method found. Their offer: diffie-hellman-group14-sha1
> 
> $ ssh -Q kex
> diffie-hellman-group1-sha1
> diffie-hellman-group14-sha1
> diffie-hellman-group14-sha256
> diffie-hellman-group16-sha512
> diffie-hellman-group18-sha512
> diffie-hellman-group-exchange-sha1
> diffie-hellman-group-exchange-sha256
> ecdh-sha2-nistp256
> ecdh-sha2-nistp384
> ecdh-sha2-nistp521
> curve25519-sha256
> curve25519-sha256@libssh.org
> sntrup4591761x25519-sha512@tinyssh.org
> 
> $ ssh admin@10.0.3.6
> Connection reset by 10.0.3.6 port 22
> 
> Complete listing:
> $ ssh -vv -oHostKeyAlgorithms=+ssh-dss -oStrictHostKeyChecking=no admin@10.0.3.6
> OpenSSH_8.3p1, OpenSSL 1.1.1f  31 Mar 2020
> debug2: resolve_canonicalize: hostname 10.0.3.6 is address
> debug2: ssh_connect_direct
> debug1: Connecting to 10.0.3.6 [10.0.3.6] port 22.
> debug1: Connection established.
> debug1: identity file /home/tester/.ssh/id_rsa type -1
> debug1: identity file /home/tester/.ssh/id_rsa-cert type -1
> debug1: identity file /home/tester/.ssh/id_dsa type -1
> debug1: identity file /home/tester/.ssh/id_dsa-cert type -1
> debug1: identity file /home/tester/.ssh/id_ecdsa type -1
> debug1: identity file /home/tester/.ssh/id_ecdsa-cert type -1
> debug1: identity file /home/tester/.ssh/id_ecdsa_sk type -1
> debug1: identity file /home/tester/.ssh/id_ecdsa_sk-cert type -1
> debug1: identity file /home/tester/.ssh/id_ed25519 type -1
> debug1: identity file /home/tester/.ssh/id_ed25519-cert type -1
> debug1: identity file /home/tester/.ssh/id_ed25519_sk type -1
> debug1: identity file /home/tester/.ssh/id_ed25519_sk-cert type -1
> debug1: identity file /home/tester/.ssh/id_xmss type -1
> debug1: identity file /home/tester/.ssh/id_xmss-cert type -1
> debug1: Local version string SSH-2.0-OpenSSH_8.3
> debug1: Remote protocol version 2.0, remote software version LiteSSH
> debug1: no match: LiteSSH
> debug2: fd 3 setting O_NONBLOCK
> debug1: Authenticating to 10.0.3.6:22 as 'admin'
> debug1: SSH2_MSG_KEXINIT sent
> debug1: SSH2_MSG_KEXINIT received
> debug2: local client KEXINIT proposal
> debug2: KEX algorithms: curve25519-sha256,curve25519-sha256@libssh.org,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,ext-info-c
> debug2: host key algorithms: ecdsa-sha2-nistp256-cert-v01@openssh.com,ecdsa-sha2-nistp384-cert-v01@openssh.com,ecdsa-sha2-nistp521-cert-v01@openssh.com,sk-ecdsa-sha2-nistp256-cert-v01@openssh.com,ssh-ed25519-cert-v01@openssh.com,sk-ssh-ed25519-cert-v01@openssh.com,rsa-sha2-512-cert-v01@openssh.com,rsa-sha2-256-cert-v01@openssh.com,ssh-rsa-cert-v01@openssh.com,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,sk-ecdsa-sha2-nistp256@openssh.com,ssh-ed25519,sk-ssh-ed25519@openssh.com,rsa-sha2-512,rsa-sha2-256,ssh-rsa,ssh-dss
> debug2: ciphers ctos: chacha20-poly1305@openssh.com,aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm@openssh.com,aes256-gcm@openssh.com
> debug2: ciphers stoc: chacha20-poly1305@openssh.com,aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm@openssh.com,aes256-gcm@openssh.com
> debug2: MACs ctos: umac-64-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha1-etm@openssh.com,umac-64@openssh.com,umac-128@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1
> debug2: MACs stoc: umac-64-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha1-etm@openssh.com,umac-64@openssh.com,umac-128@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1
> debug2: compression ctos: none,zlib@openssh.com,zlib
> debug2: compression stoc: none,zlib@openssh.com,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
> debug2: host key algorithms: ssh-rsa
> debug2: ciphers ctos: aes256-ctr
> debug2: ciphers stoc: aes256-ctr
> debug2: MACs ctos: hmac-sha1
> debug2: MACs stoc: hmac-sha1
> 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: (no match)
> Unable to negotiate with 10.0.3.6 port 22: no matching key exchange method found. Their offer: diffie-hellman-group14-sha1

Do these help?

	https://www.openssh.com/legacy.html

	https://www.ssh.com/ssh/sshd_config/

https://unix.stackexchange.com/questions/340844/how-to-enable-diffie-hellman-group1-sha1-key-exchange-on-debian-8-0

Curl cygport check uses kex a lot in its tests so that might give you some help.
You could check it out online under

	https://github.com/curl/curl/tree/master/tests

download the package sources, or I could PM you selected generated or log files,
if you know what you want to see.

-- 
Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada

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