ssh connect to server stop on "SSH2_MSG_KEXINIT sent"

[aruslan]

After upgrade on Ubuntu 22.04 i can't connect to several servers. Connecting stopped on SSH2_MSG_KEXINIT sent
```
 ssh -vvv -o KexAlgorithms=diffie-hellman-group-exchange-sha256 -oHostKeyAlgorithms=+ssh-rsa -X vld@sansa
OpenSSH_8.9p1 Ubuntu-3, OpenSSL 3.0.2 15 Mar 2022
debug1: Reading configuration data /home/ruslan/.ssh/config
debug3: kex names ok: [diffie-hellman-group1-sha1]
debug3: kex names ok: [diffie-hellman-group-exchange-sha256,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1]
debug3: kex names ok: [diffie-hellman-group1-sha1]
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 19: include /etc/ssh/ssh_config.d/*.conf matched no files
debug1: /etc/ssh/ssh_config line 21: Applying options for *
debug3: expanded UserKnownHostsFile '~/.ssh/known_hosts' -> '/home/ruslan/.ssh/known_hosts'
debug3: expanded UserKnownHostsFile '~/.ssh/known_hosts2' -> '/home/ruslan/.ssh/known_hosts2'
debug2: resolving "sansa" port 22
debug3: resolve_host: lookup sansa:22
debug3: ssh_connect_direct: entering
debug1: Connecting to sansa [172.16.xx.xx] port 22.
debug3: set_sock_tos: set socket 3 IP_TOS 0x10
debug1: Connection established.
debug1: identity file /home/ruslan/.ssh/id_rsa type -1
debug1: identity file /home/ruslan/.ssh/id_rsa-cert type -1
debug1: identity file /home/ruslan/.ssh/id_ecdsa type -1
debug1: identity file /home/ruslan/.ssh/id_ecdsa-cert type -1
debug1: identity file /home/ruslan/.ssh/id_ecdsa_sk type -1
debug1: identity file /home/ruslan/.ssh/id_ecdsa_sk-cert type -1
debug1: identity file /home/ruslan/.ssh/id_ed25519 type -1
debug1: identity file /home/ruslan/.ssh/id_ed25519-cert type -1
debug1: identity file /home/ruslan/.ssh/id_ed25519_sk type -1
debug1: identity file /home/ruslan/.ssh/id_ed25519_sk-cert type -1
debug1: identity file /home/ruslan/.ssh/id_xmss type -1
debug1: identity file /home/ruslan/.ssh/id_xmss-cert type -1
debug1: identity file /home/ruslan/.ssh/id_dsa type -1
debug1: identity file /home/ruslan/.ssh/id_dsa-cert type -1
debug1: Local version string SSH-2.0-OpenSSH_8.9p1 Ubuntu-3
debug1: Remote protocol version 2.0, remote software version OpenSSH_5.3
debug1: compat_banner: match: OpenSSH_5.3 pat OpenSSH_5* compat 0x0c000002
debug2: fd 3 setting O_NONBLOCK
debug1: Authenticating to sansa:22 as 'vld'
debug1: load_hostkeys: fopen /etc/ssh/ssh_known_hosts2: No such file or directory
debug3: order_hostkeyalgs: no algorithms matched; accept original
debug3: send packet: type 20
debug1: SSH2_MSG_KEXINIT sent

```
I'm checking connection on old version Ubuntu 20.04, it's working. Remote server use
KexAlgorithms=diffie-hellman-group-exchange-sha256 and HostKeyAlgorithms=ssh-rsa

On Ubuntu 21.04 ssh was work.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Brian Murray (brian-murray)]

This is documented in the release note for Jammy Jellyfish (https://discourse.ubuntu.com/t/jammy-jellyfish-release-notes/24668):

ssh-rsa is now disabled by default in OpenSSH 237.

The release notes also contain a link to a way to continue connetcing to servers configured with ssh-rsa.

[aruslan (taomao)]

Could the problem be something else? Adding the old algorithm to the configuration did not help me.

Example in config
Host old-host
    HostkeyAlgorithms +ssh-rsa
    PubkeyAcceptedAlgorithms +ssh-rsa

And try with cli options
ssh -vvv -X -oPubkeyAcceptedAlgorithms=+ssh-rsa -oHostkeyAlgorithms=+ssh-rsa dual
debug1: load_hostkeys: fopen /etc/ssh/ssh_known_hosts2: No such file or directory
debug3: order_hostkeyalgs: no algorithms matched; accept original
debug3: send packet: type 20
debug1: SSH2_MSG_KEXINIT sent

[Gerald Skead (skeadster)]

Confirmed adding entry to .ssh/config solved it for me.

My example for each old host:

Host x.x.x.x
        HostkeyAlgorithms +ssh-rsa
PubkeyAcceptedAlgorithms +ssh-rsa