Bug#1006463: openssh-server: Can't login on two i386 boxes anymore since the server-side has been upgraded to 8.9p1: "debug1: expecting SSH2_MSG_KEX_ECDH_REPLY" -> also affects armhf

Control: retitle -1 openssh-server: Can't login on any 32-bit box anymore after the server-side has been upgraded to 8.9p1: "debug1: expecting SSH2_MSG_KEX_ECDH_REPLY"

Hi,

Axel Beckert wrote:
> TL;DR: OpenSSH clients (at least 8.8 and 8.9) can't talk with OpenSSH
> 8.9 servers in some cases (common property so far: if and only if it's
> i386 on the server-side),

Found another case, this time Sid armhf (a Raspberry Pi 2) on the
server-side, i.e. also a 32-bit architecture:

~ → ssh -v 192.168.1.152
OpenSSH_8.9p1 Debian-2, OpenSSL 1.1.1m  14 Dec 2021
debug1: Reading configuration data /home/abe/.ssh/config
debug1: /home/abe/.ssh/config line 1: Applying options for *
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 *
debug1: Connecting to 192.168.1.152 [192.168.1.152] port 22.
debug1: Connection established.
debug1: identity file /home/abe/.ssh/id_rsa type 0
debug1: identity file /home/abe/.ssh/id_rsa-cert type -1
debug1: identity file /home/abe/.ssh/id_ecdsa type 2
debug1: identity file /home/abe/.ssh/id_ecdsa-cert type -1
debug1: identity file /home/abe/.ssh/id_ecdsa_sk type -1
debug1: identity file /home/abe/.ssh/id_ecdsa_sk-cert type -1
debug1: identity file /home/abe/.ssh/id_ed25519 type 3
debug1: identity file /home/abe/.ssh/id_ed25519-cert type -1
debug1: identity file /home/abe/.ssh/id_ed25519_sk type -1
debug1: identity file /home/abe/.ssh/id_ed25519_sk-cert type -1
debug1: identity file /home/abe/.ssh/id_xmss type -1
debug1: identity file /home/abe/.ssh/id_xmss-cert type -1
debug1: identity file /home/abe/.ssh/id_dsa type -1
debug1: identity file /home/abe/.ssh/id_dsa-cert type -1
debug1: Local version string SSH-2.0-OpenSSH_8.9p1 Debian-2
debug1: Remote protocol version 2.0, remote software version OpenSSH_8.9p1 Debian-2
debug1: compat_banner: match: OpenSSH_8.9p1 Debian-2 pat OpenSSH* compat 0x04000000
debug1: Authenticating to 192.168.1.152:22 as 'abe'
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: rsa-sha2-512
debug1: kex: server->client cipher: [email protected] MAC: <implicit> compression: none
debug1: kex: client->server cipher: [email protected] MAC: <implicit> compression: none
debug1: expecting SSH2_MSG_KEX_ECDH_REPLY
ssh_dispatch_run_fatal: Connection to 192.168.1.152 port 22: Broken pipe

Currently looks to me as if 8.9 on the server-side is generally broken
iff the server runs on a 32-bit architectures. Al least all Sid 32-bit
architecture boxes I tried so far, failed with the same symptoms.

		Regards, Axel