準備作業

openssh低版本存在安全漏洞，所以升級至新版本，由于是生產環境所以采用的是離線版本，

• Linux系統為Redhat7
• ssh當前版本為6.6.1，升級至8.4版本，
• 下載依賴包openssh 8.4安裝包

wget https://ftp.openbsd.org/pub/OpenBSD/OpenSSH/portable/openssh-8.4p1.tar.gz

• 下載pam安裝包
  鏈接: https://pan.baidu.com/s/1q6PpkRYtCwLFuYoN1Q87LQ 提取碼: ycps 復制這段內容后打開百度網盤（免費鏈接）

開始升級

• 安裝包 依賴包上次到/home/eastcom/目錄中并解壓

tar zxf openssh-8.1p1.tar.gz

• 給新版本檔案加root權限

chown -R root.root /home/eastcom/openssh-8.4p1

• 老檔案進行備份到/home/eastcom/目錄

cp -r /etc/ssh/ /home/eastcom/

• 安裝依賴包

rpm -ivh pam-devel-1.1.8-18.el7.x86_64.rpm

• 洗掉老檔案

rm -rf /etc/ssh/*

• 進入新版本openssh-8.4p1目錄中

cd /home/eastcom/openssh-8.4p1

• 執行編譯安裝

./configure --prefix=/usr/ --sysconfdir=/etc/ssh  --with-openssl-includes=/usr/local/ssl/include  --with-ssl-dir=/usr/local/ssl   --with-zlib   --with-md5-passwords   --with-pam  && make && make install

• 查看編譯安裝狀態，（0是成功，其他數值為失敗）

echo $?

• 編輯ssh的組態檔

vi /etc/ssh/sshd_config

     Ciphers aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm@openssh.com,aes256-gcm@openssh.com,chacha20-poly1305@openssh.com

     MACs hmac-sha2-256,hmac-sha2-512,hmac-sha1
     KexAlgorithms ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1
    #PermitRootLogin yes

• 拷貝當前目錄檔案到可執行檔案并改名

cp -a contrib/redhat/sshd.init /etc/init.d/sshd
cp -a contrib/redhat/sshd.pam /etc/pam.d/sshd.pam

• 給ssh啟動檔案加可執行權限

chmod +x /etc/init.d/sshd

chkconfig --add sshd

systemctl enable sshd

• 原執行檔案洗掉或者移動到其他檔案目錄中

mv  /usr/lib/systemd/system/sshd.service  /home/

chkconfig sshd on

systemctl enable sshd.socket

• 啟動sshd服務

systemctl restart sshd

注：沒有錯誤才能算成功

• 查詢下升級后的ssh版本

ssh -V
OpenSSH_8.4p1, OpenSSL 1.0.2k-fips  26 Jan 2017

啟動錯誤及解決方案

錯誤1 提示權限錯誤

[root@db-01 eastcom]# systemctl status sshd
● sshd.service - SYSV: OpenSSH server daemon
   Loaded: loaded (/etc/rc.d/init.d/sshd; bad; vendor preset: enabled)
   Active: failed (Result: exit-code) since Tue 2020-11-03 15:08:27 CST; 1min 58s ago
     Docs: man:systemd-sysv-generator(8)
  Process: 14206 ExecStart=/etc/rc.d/init.d/sshd start (code=exited, status=1/FAILURE)
 Main PID: 1355 (code=exited, status=0/SUCCESS)
   CGroup: /system.slice/sshd.service
           └─19856 /usr/sbin/sshd

Nov 03 15:08:27 db-01 sshd[14206]: @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
Nov 03 15:08:27 db-01 sshd[14206]: Permissions 0640 for '/etc/ssh/ssh_host_ed25519_key' are too open.
Nov 03 15:08:27 db-01 sshd[14206]: It is required that your private key files are NOT accessible by others.
Nov 03 15:08:27 db-01 sshd[14206]: This private key will be ignored.
Nov 03 15:08:27 db-01 sshd[14206]: sshd: no hostkeys available -- exiting.
Nov 03 15:08:27 db-01 systemd[1]: sshd.service: control process exited, code=exited status=1
Nov 03 15:08:27 db-01 sshd[14206]: [FAILED]
Nov 03 15:08:27 db-01 systemd[1]: Failed to start SYSV: OpenSSH server daemon.
Nov 03 15:08:27 db-01 systemd[1]: Unit sshd.service entered failed state.
Nov 03 15:08:27 db-01 systemd[1]: sshd.service failed.

解決方案:

chmod 600 /etc/ssh/ssh_host_rsa_key /etc/ssh/ssh_host_ecdsa_key /etc/ssh/ssh_host_ed25519_key

• 重啟sshd服務

systemctl restart sshd

錯誤2 提示行程已存在

-- Unit sshd.service has begun starting up.
Nov 03 16:10:04 db-02 sshd[22919]: Starting sshd:GMSSL: pem_lib.c 863: pem_str = RSA PRIVATE KEY
Nov 03 16:10:04 db-02 sshd[22919]: GMSSL: pem_lib.c 864: suffix = PRIVATE KEY
Nov 03 16:10:04 db-02 sshd[22919]: GMSSL: pem_lib.c 869: p = PRIVATE KEY
Nov 03 16:10:04 db-02 sshd[22919]: GMSSL: pem_lib.c 863: pem_str = RSA PRIVATE KEY
Nov 03 16:10:04 db-02 sshd[22919]: GMSSL: pem_lib.c 864: suffix = PRIVATE KEY
Nov 03 16:10:04 db-02 sshd[22919]: GMSSL: pem_lib.c 869: p = PRIVATE KEY
Nov 03 16:10:04 db-02 sshd[22919]: GMSSL: pem_lib.c 863: pem_str = EC PRIVATE KEY
Nov 03 16:10:04 db-02 sshd[22919]: GMSSL: pem_lib.c 864: suffix = PRIVATE KEY
Nov 03 16:10:04 db-02 sshd[22919]: GMSSL: pem_lib.c 869: p = PRIVATE KEY
Nov 03 16:10:04 db-02 sshd[22919]: GMSSL: pem_lib.c 863: pem_str = EC PRIVATE KEY
Nov 03 16:10:04 db-02 sshd[22919]: GMSSL: pem_lib.c 864: suffix = PRIVATE KEY
Nov 03 16:10:04 db-02 sshd[22919]: GMSSL: pem_lib.c 869: p = PRIVATE KEY
Nov 03 16:10:04 db-02 sshd[22925]: error: Bind to port 22 on 0.0.0.0 failed: Address already in use.
Nov 03 16:10:04 db-02 sshd[22925]: error: Bind to port 22 on :: failed: Address already in use.
Nov 03 16:10:04 db-02 sshd[22925]: fatal: Cannot bind any address.
Nov 03 16:10:04 db-02 sshd[22919]: [  OK  ]
Nov 03 16:10:04 db-02 systemd[1]: PID file /var/run/sshd.pid not readable (yet?) after start.
Nov 03 16:15:05 db-02 systemd[1]: sshd.service start operation timed out. Terminating.
Nov 03 16:15:05 db-02 systemd[1]: Failed to start SYSV: OpenSSH server daemon.
-- Subject: Unit sshd.service has failed
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
-- 
-- Unit sshd.service has failed.
-- 
-- The result is failed.
Nov 03 16:15:05 db-02 systemd[1]: Unit sshd.service entered failed state.
Nov 03 16:15:05 db-02 systemd[1]: sshd.service failed.
Nov 03 16:15:05 db-02 polkitd[992]: Unregistered Authentication Agent for unix-process:22913:943361681 (system bus name :1.5403, object path /org/freedesktop

解決方案：

ps -ef|grep sshd
#kill掉行程即可

• 重啟sshd服務

systemctl restart sshd

錯誤 3 主機連接失敗

eastcom@server-01 ~]$ ssh root@196.168.10.72
/etc/ssh/ssh_config line 25: Unsupported option "gssapiauthentication"
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@    WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED!     @
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!
Someone could be eavesdropping on you right now (man-in-the-middle attack)!
It is also possible that a host key has just been changed.
The fingerprint for the ECDSA key sent by the remote host is
SHA256:oXp8kQKrgUko1oc7UeG8cZRfHolQlPwIngqeNQGCYxA.
Please contact your system administrator.
Add correct host key in /home/eastcom/.ssh/known_hosts to get rid of this message.
Offending ECDSA key in /home/eastcom/.ssh/known_hosts:3
ECDSA host key for 196.168.10.72 has changed and you have requested strict checking.
Host key verification failed.

解決方案：

#洗掉本地known_hosts里面的快取資訊即可，命令：ssh-keygen -R "你的遠程服務器ip地址"  
ssh-keygen -R "196.168.10.72"