直接生成ed25519 

ssh-keygen -t ed25519 -C ""

如果需要带hostname可以把-C参数去掉， 默认生成   ~/.ssh/id_ed25519和~/.ssh/id_ed25519.pub

pub文件内容存入登录服务器~/.ssh/authorized_keys后， 直接用ssh 用户@IP 直接登录

生成过程示例

#示例运行账号是root，所以显示的路径是/root/.ssh/
ssh-keygen -t ed25519 -C ""                                                                                          #开始生成， 去掉-C参数则会带hostname信息， 也可以 用-C输入指定信息用于识别
Generating public/private ed25519 key pair.                                                                 #提示信息
Enter file in which to save the key (/root/.ssh/id_ed25519):                                        #询问保存路径，一般默认就行也可以指定。
Enter passphrase for "/root/.ssh/id_ed25519" (empty for no passphrase):              #输入你的私钥密码，直接回车则不设置密码，但不建议。
Enter same passphrase again:                                                                                        #重复私钥密码
Your identification has been saved in /root/.ssh/id_ed25519                                      #生成的私钥
Your public key has been saved in /root/.ssh/id_ed25519.pub                                    #生成的公钥
The key fingerprint is:                                                                                                     #已下是提示信息
SHA256:+o0845BYVdSsxxxxxxxxxxxxxxPNy3OfgM
The key's randomart image is:
+--[ED25519 256]--+
| .oB++oo .oo     |
|. . o . ... o    |
| o   .  .= .     |
|  o + o.o *      |
|   + +..S= *     |
|    Eo.o+ * +    |
|   ..o+. . + .   |
|    . o+oo       |
|     . o=o.      |
+----[SHA256]-----+

generate.sh内容

#!/usr/bin/env bash
set -euo pipefail
KEY="$HOME/.ssh/id_ed25519"
mkdir -p "$HOME/.ssh"
chmod 700 "$HOME/.ssh"
if [[ -e "$KEY" || -e "$KEY.pub" ]]; then
    echo "错误：密钥文件已存在：$KEY"
    echo "为避免覆盖现有密钥，请先备份或手动处理。"
    exit 1
fi
ssh-keygen -t ed25519 -f "$KEY" -C ""
chmod 600 "$KEY"
chmod 644 "$KEY.pub"
echo
echo "密钥生成完成："
echo "私钥：$KEY"
echo "公钥：$KEY.pub"

添加密钥让系统记住私钥密码

eval "$(ssh-agent -s)"
ssh-add ~/.ssh/id_ed25519

MacOS添加密钥

ssh-add --apple-use-keychain ~/.ssh/id_ed25519

示例设置密钥缓存有效期8小时

eval "$(ssh-agent -s)"
ssh-add -t 8h ~/.ssh/id_ed25519

查看已加载的密钥

ssh-add -l

查看具体公钥：

ssh-add -L

ps：Windows下有安装openssh-client的也是类似方式

Linux下借助 keychain长期记住私钥密码方法

#这里用apt为例子
apt update
apt install keychain -y

cat>>~/.bashrc<<EOF
eval "\$(keychain --eval --quiet ~/.ssh/id_ed25519)"
EOF
source ~/.bashrc

ssh-keygen除了ed25519还有rsa和ecdsa可选，建议用大一点的算法参数，dsa已经属于淘汰类型不建议使用，都大同小异，rsa兼容性好，ed25519的密文比较简短。

ssh-keygen参数选择预览

# ssh-keygen ?
Too many arguments.
usage: ssh-keygen [-q] [-a rounds] [-b bits] [-C comment] [-f output_keyfile]
                  [-m format] [-N new_passphrase] [-O option]
                  [-t dsa | ecdsa | ecdsa-sk | ed25519 | ed25519-sk | rsa]
                  [-w provider] [-Z cipher]
       ssh-keygen -p [-a rounds] [-f keyfile] [-m format] [-N new_passphrase]
                   [-P old_passphrase] [-Z cipher]
       ssh-keygen -i [-f input_keyfile] [-m key_format]
       ssh-keygen -e [-f input_keyfile] [-m key_format]
       ssh-keygen -y [-f input_keyfile]
       ssh-keygen -c [-a rounds] [-C comment] [-f keyfile] [-P passphrase]
       ssh-keygen -l [-v] [-E fingerprint_hash] [-f input_keyfile]
       ssh-keygen -B [-f input_keyfile]
       ssh-keygen -D pkcs11
       ssh-keygen -F hostname [-lv] [-f known_hosts_file]
       ssh-keygen -H [-f known_hosts_file]
       ssh-keygen -K [-a rounds] [-w provider]
       ssh-keygen -R hostname [-f known_hosts_file]
       ssh-keygen -r hostname [-g] [-f input_keyfile]
       ssh-keygen -M generate [-O option] output_file
       ssh-keygen -M screen [-f input_file] [-O option] output_file
       ssh-keygen -I certificate_identity -s ca_key [-hU] [-D pkcs11_provider]
                  [-n principals] [-O option] [-V validity_interval]
                  [-z serial_number] file ...
       ssh-keygen -L [-f input_keyfile]
       ssh-keygen -A [-a rounds] [-f prefix_path]
       ssh-keygen -k -f krl_file [-u] [-s ca_public] [-z version_number]
                  file ...
       ssh-keygen -Q [-l] -f krl_file [file ...]
       ssh-keygen -Y find-principals -s signature_file -f allowed_signers_file
       ssh-keygen -Y match-principals -I signer_identity -f allowed_signers_file
       ssh-keygen -Y check-novalidate -n namespace -s signature_file
       ssh-keygen -Y sign -f key_file -n namespace file [-O option] ...
       ssh-keygen -Y verify -f allowed_signers_file -I signer_identity
                  -n namespace -s signature_file [-r krl_file] [-O option]