Ubuntu 14.04 > 18.04 ssh 说“格式无效”

我最近将主机从 Ubuntu 14.04 升级到 18.04，当我尝试ssh在 18.04 下使用时，我收到错误消息key_load_public: invalid format。

我在此主机（和远程）上使用的密钥对的公钥部分如下所示：

command="/root/bin/rsync_only" ssh-rsa AAAAB...kEzWH0cMQ== root@vargas

似乎如果我删除该command=部分，我不会收到invalid format错误消息。它多年来一直运行良好。有人知道为什么现在这是一个问题吗？

/root/bin/rsync_only

#!/bin/sh
case "$SSH_ORIGINAL_COMMAND" in
   *\&*)
            echo "Rejected"
   ;;

   *\;*)
            echo "Rejected"
   ;;

   rsync\ --server*)
            $SSH_ORIGINAL_COMMAND
   ;;

   *)
            echo "Rejected"
   ;;
esac

ssh -vvv

# ssh remote_host -i ~/.ssh/id_rsync -vvv
OpenSSH_7.6p1 Ubuntu-4ubuntu0.3, OpenSSL 1.0.2n  7 Dec 2017
debug1: Reading configuration data /root/.ssh/config
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 19: Applying options for *
debug2: resolving "remote_host" port 22
debug2: ssh_connect_direct: needpriv 0
debug1: Connecting to remote_host [10.10.16.1] port 22.
debug1: Connection established.
debug1: permanently_set_uid: 0/0
key_load_public: invalid format
...

来自 Ubuntu 14.04 的 ssh 和 -vvv 输出

ubuntu-14.04 # ssh remote_host -i ~/.ssh/id_rsync     
Rejected
Connection to remote_host closed.

ubuntu-14.04# ssh remote_host -i ~/.ssh/id_rsync -vvv
OpenSSH_6.6.1, OpenSSL 1.0.1f 6 Jan 2014
debug1: Reading configuration data /root/.ssh/config
debug1: Reading configuration data /etc/ssh/ssh_config
debug2: ssh_connect: needpriv 0
debug1: Connecting to remote_host [10.10.16.1] port 22.
debug1: Connection established.
debug1: permanently_set_uid: 0/0
debug3: Incorrect RSA1 identifier
debug3: Could not load "/root/.ssh/id_rsync" as a RSA1 public key
debug2: key_type_from_name: unknown key type 'command="/root/bin/rsync_only"'
debug3: key_read: missing keytype
...