Rocky Linux 8.6
libssh-0.9.6

This is the output from nmap ssh2-enum-algos:

> nmap --script ssh2-enum-algos  10.1.1.1
Starting Nmap 7.92
Nmap scan report for 10.1.1.1
Host is up (0.0045s latency).
Not shown: 992 filtered tcp ports (no-response)
PORT     STATE  SERVICE
22/tcp   open   ssh
| ssh2-enum-algos:
|   kex_algorithms: (10)
|       curve25519-sha256
|       [email protected]
|       ecdh-sha2-nistp256
|       ecdh-sha2-nistp384
|       ecdh-sha2-nistp521
|       diffie-hellman-group-exchange-
|       diffie-hellman-group16-sha512
|       diffie-hellman-group18-sha512
|       diffie-hellman-group14-sha256
|       diffie-hellman-group14-sha1
|   server_host_key_algorithms: (5)
|       rsa-sha2-512
|       rsa-sha2-256
|       ssh-rsa
|       ecdsa-sha2-nistp256
|       ssh-ed25519
|   encryption_algorithms: (6)
|       [email protected]
|       aes128-ctr
|       aes192-ctr
|       aes256-ctr
|       [email protected]
|       [email protected]
|   mac_algorithms: (10)
|       [email protected]
|       [email protected]
|       [email protected]
|       [email protected]
|       [email protected]
|       [email protected]
|       [email protected]
|       hmac-sha2-256
|       hmac-sha2-512
|       hmac-sha1
|   compression_algorithms: (2)
|       none
|_      [email protected]

This is a manual ssh connection with debug info:

[root@VZABBIX ~]# ssh -vvv 10.1.1.2
OpenSSH_8.0p1, OpenSSL 1.1.1k  FIPS 25 Mar 2021
debug1: Reading configuration data /etc/ssh/ssh_config
debug3: /etc/ssh/ssh_config line 52: Including file /etc/ssh/ssh_config.d/05-
debug1: Reading configuration data /etc/ssh/ssh_config.d/05-
debug2: checking match for 'final all' host 10.1.1.2 originally 10.1.1.2
debug3: /etc/ssh/ssh_config.d/05-
debug2: match not found
debug3: /etc/ssh/ssh_config.d/05-
debug1: Reading configuration data /etc/crypto-policies/back-
debug3: gss kex names ok: [gss-curve25519-sha256-,gss-
debug3: kex names ok: [curve25519-sha256,curve25519-,ecdh-sha2-
debug1: configuration requests final Match pass
debug2: resolve_canonicalize: hostname 10.1.1.2 is address
debug1: re-parsing configuration
debug1: Reading configuration data /etc/ssh/ssh_config
debug3: /etc/ssh/ssh_config line 52: Including file /etc/ssh/ssh_config.d/05-
debug1: Reading configuration data /etc/ssh/ssh_config.d/05-
debug2: checking match for 'final all' host 10.1.1.2 originally 10.1.1.2
debug3: /etc/ssh/ssh_config.d/05-
debug2: match found
debug3: /etc/ssh/ssh_config.d/05-
debug1: Reading configuration data /etc/crypto-policies/back-
debug3: gss kex names ok: [gss-curve25519-sha256-,gss-
debug3: kex names ok: [curve25519-sha256,curve25519-,ecdh-sha2-
debug2: ssh_connect_direct
debug1: Connecting to 10.1.1.2 [10.1.1.2] port 22.
debug1: Connection established.
debug1: identity file /root/.ssh/id_rsa type -1
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 OpenSSH_8.0
debug1: match: OpenSSH_8.0 pat OpenSSH* compat 0x04000000
debug2: fd 5 setting O_NONBLOCK
debug1: Authenticating to 10.1.1.2:22 as 'root'
debug3: hostkeys_foreach: reading file "/root/.ssh/known_hosts"
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,curve25519-,ecdh-sha2-
debug2: host key algorithms: ecdsa-sha2-nistp256-cert-v01@,ecdsa-sha2-,,ssh-ed25519-cert-,rsa-sha2-512-,rsa-sha2-,ssh-,
debug2: ciphers ctos: [email protected],chacha2,aes256-aes128-gcm@,aes128-ctr,aes128-
debug2: ciphers stoc: [email protected],chacha2,aes256-aes128-gcm@,aes128-ctr,aes128-
debug2: MACs ctos: [email protected],,umac,hmac-,hmac-umac-128@,hmac-sha2-512
debug2: MACs stoc: [email protected],,umac,hmac-,hmac-umac-128@,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: curve25519-sha256,curve25519-,ecdh-sha2-
debug2: host key algorithms: rsa-sha2-512,rsa-sha2-256,ssh-
debug2: ciphers ctos: [email protected],[email protected],aes
debug2: ciphers stoc: [email protected],[email protected],aes
debug2: MACs ctos: [email protected],umac-,hmac-sha2-,hmac-sha2-,hmac-sha1-,umac-64@,umac-128@openssh.,hmac-sha2-256,hmac-sha2-
debug2: MACs stoc: [email protected],umac-,hmac-sha2-,hmac-sha2-,hmac-sha1-,umac-64@,umac-128@openssh.,hmac-sha2-256,hmac-sha2-
debug2: compression ctos: none,[email protected]
debug2: compression stoc: none,[email protected]
debug2: languages ctos:
debug2: languages stoc:
debug2: first_kex_follows 0
debug2: reserved 0
debug1: kex: algorithm: curve25519-sha256
debug1: kex: host key algorithm: ecdsa-sha2-nistp256
debug1: kex: server->client cipher: [email protected] MAC: <implicit> compression: none
debug1: kex: client->server cipher: [email protected] MAC: <implicit> compression: none
debug1: kex: curve25519-sha256 need=32 dh_need=32
debug1: kex: curve25519-sha256 need=32 dh_need=32
debug3: send packet: type 30
debug1: expecting SSH2_MSG_KEX_ECDH_REPLY
debug3: receive packet: type 31
debug1: Server host key: ecdsa-sha2-nistp256 SHA256:+/Wmpe8/
debug3: hostkeys_foreach: reading file "/root/.ssh/known_hosts"
The authenticity of host '10.1.1.2 (10.1.1.2)' can't be established.
ECDSA key fingerprint is SHA256:+/Wmpe8/
Are you sure you want to continue connecting (yes/no/[fingerprint])? yes
Warning: Permanently added '10.1.1.2' (ECDSA) to the list of known hosts.
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
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 7
debug1: SSH2_MSG_EXT_INFO received
debug1: kex_input_ext_info: server-sig-algs=<ssh-ed25519,
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 52
debug1: Authentication succeeded (none).
Authenticated to 10.1.1.2 ([10.1.1.2]:22).
debug1: channel 0: new [client-session]
debug3: ssh_session2_open: channel_new: 0
debug2: channel 0: send open
debug3: send packet: type 90
debug1: Requesting [email protected]
debug3: send packet: type 80
debug1: Entering interactive session.
debug1: pledge: network
debug3: receive packet: type 80
debug1: client_input_global_request: rtype [email protected] want_reply 0
debug3: receive packet: type 91
debug2: channel_input_open_
debug2: fd 5 setting TCP_NODELAY
debug3: ssh_packet_set_tos: set IP_TOS 0x48
debug2: client_session2_setup: id 0
debug2: channel 0: request pty-req confirm 1
debug3: send packet: type 98
debug1: Sending environment.
debug3: Ignored env LS_COLORS
debug3: Ignored env SSH_CONNECTION
debug1: Sending env LANG = en_US.UTF-8
debug2: channel 0: request env confirm 0
debug3: send packet: type 98
debug3: Ignored env HISTCONTROL
debug3: Ignored env HOSTNAME
debug3: Ignored env which_declare
debug3: Ignored env XDG_SESSION_ID
debug3: Ignored env USER
debug3: Ignored env SELINUX_ROLE_REQUESTED
debug3: Ignored env PWD
debug3: Ignored env HOME
debug3: Ignored env SSH_CLIENT
debug3: Ignored env SELINUX_LEVEL_REQUESTED
debug3: Ignored env SSH_TTY
debug3: Ignored env MAIL
debug3: Ignored env TERM
debug3: Ignored env SHELL
debug3: Ignored env SELINUX_USE_CURRENT_RANGE
debug3: Ignored env SHLVL
debug3: Ignored env LOGNAME
debug3: Ignored env DBUS_SESSION_BUS_ADDRESS
debug3: Ignored env XDG_RUNTIME_DIR
debug3: Ignored env PATH
debug3: Ignored env HISTSIZE
debug3: Ignored env LESSOPEN
debug3: Ignored env BASH_FUNC_which%%
debug3: Ignored env _
debug2: channel 0: request shell confirm 1
debug3: send packet: type 98
debug2: channel_input_open_
debug2: channel 0: open confirm rwindow 0 rmax 32768
debug3: receive packet: type 99
debug2: channel_input_status_confirm: type 99 id 0
debug2: PTY allocation request accepted on channel 0
debug2: channel 0: rcvd adjust 2097152
debug3: receive packet: type 99
debug2: channel_input_status_confirm: type 99 id 0
debug2: shell request accepted on channel 0

Thank you for detailed report.

Could you say what library installed for that zabbix server? Does it zabbix 6.2.6?

Actually it's zabbix 6.2.4 (we may update to 6.2.6 if that helps)

zabbix-server-pgsql-6.2.4-release1.el8.x86_64

openssh-8.0p1-13.el8.x86_64
libssh-config-0.9.6-3.el8.noarch
libssh-0.9.6-3.el8.x86_64
openssh-clients-8.0p1-13.el8.x86_64
openssl-libs-1.1.1k-7.el8_6.x86_64

Thanks