https://cloudflare.cdn.openbsd.org/pub/OpenBSD/OpenSSH/

which sshd
/usr/sbin/sshd
# 查看ssh安装位置

# SSH客户端版本
ssh -V
# SSH服务端版本
sshd -V

sudo cp -rp /etc/pam.d/sshd /etc/pam.d/sshd.bak
sudo cp -rp /etc/ssh /etc/ssh_bak
sudo cp -ar /etc/init.d/sshd /etc/init.d/sshd.bak
sudo cp -ar /usr/bin/ssh /usr/bin/ssh.bak
sudo cp -ar /usr/sbin/sshd /usr/sbin/sshd_bak

cp -ar /etc/ssh_bak /etc/ssh

# 在线安装
yum install -y telnet telnet-server xinetd

# 本地安装
yum localinstall telnet-server-0.17-65.el7_8.x86_64.rpm -y
# 查询是否安装
rpm -qa | grep telnet
# 备份telnet配置文件
cp -rp /etc/securetty /etc/securetty.bak

#配置telnet登录的终端类型,增加一些pts终端
pts=$'pts/0\npts/1\npts/2\npts/3' && echo "$pts" >> /etc/securetty
vi /etc/services
#去掉23端口的注释
#配置文件
vi /etc/xinetd.d/telnet
将disable=yes改为disable=no

# 启动telnet服务
systemctl start telnet.socket
service xinetd start

# iptables放行23端口
iptables -I INPUT 1 -p tcp --dport 23  -j ACCEPT -m comment --comment "放行23端口"
iptables-save

firewall-cmd --zone=public --add-port=23/tcp --permanent
firewall-cmd --reload

sudo yum localinstall pam-devel-1.1.8-23.el7.x86_64.rpm pam-1.1.8-23.el7.x86_64.rpm openssl-devel-1.0.2k-19.el7.x86_64.rpm openssl-libs-1.0.2k-19.el7.x86_64.rpm zlib-devel-1.2.7-18.el7.x86_64.rpm openssl-1.0.2k-19.el7.x86_64.rpm -y

scp username@remote_host:/usr/local/src/filename /usr/local/src/
scp smmc@192.168.115.40:/home/smmc/tjp/*.rpm /home/smmc/
# 注意权限问题
# 或者使用本地XFTP看看能不能连上

re -be

./configure  --sysconfdir=/etc/ssh --with-md5-passwords --with-pam --with-ssl-dir=/usr/local/openssl 

configure: WARNING: unrecognized options: --with-md5-passwords

OpenSSH has been configured with the following options:
                     User binaries: /usr/local/bin
                   System binaries: /usr/local/sbin
               Configuration files: /etc/ssh
                   Askpass program: /usr/local/libexec/ssh-askpass
                      Manual pages: /usr/local/share/man/manX
                          PID file: /var/run
  Privilege separation chroot path: /var/empty
            sshd default user PATH: /usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin
                    Manpage format: doc
                       PAM support: yes
                   OSF SIA support: no
                 KerberosV support: no
                   SELinux support: no
                   libedit support: no
                   libldns support: no
  Solaris process contract support: no
           Solaris project support: no
         Solaris privilege support: no
       IP address in $DISPLAY hack: no
           Translate v4 in v6 hack: yes
                  BSD Auth support: no
              Random number source: OpenSSL internal ONLY
             Privsep sandbox style: seccomp_filter
                   PKCS#11 support: yes
                  U2F/FIDO support: yes

              Host: x86_64-pc-linux-gnu
          Compiler: cc -std=gnu11
    Compiler flags: -g -O2 -pipe -Wall -Wpointer-arith -Wuninitialized -Wsign-compare -Wformat-security -Wsizeof-pointer-memaccess -Wno-pointer-sign -Wno-unused-result -fno-strict-aliasing -D_FORTIFY_SOURCE=2 -ftrapv -fno-builtin-memset -fstack-protector-strong -fPIE
Preprocessor flags:  -D_XOPEN_SOURCE=600 -D_BSD_SOURCE -D_DEFAULT_SOURCE -D_GNU_SOURCE
      Linker flags:  -Wl,-z,relro -Wl,-z,now -Wl,-z,noexecstack -fstack-protector-strong -pie
         Libraries: -ldl -lutil  -lresolv
     +for channels: -lcrypto  -lz
         +for sshd: -lcrypt  -lpam

PAM is enabled. You may need to install a PAM control file
for sshd, otherwise password authentication may fail.
Example PAM control files can be found in the contrib/
subdirectory

# 编译并安装
sudo make && sudo make install

service xinetd stop

systemctl stop xinetd.service

/bin/mkdir -p /etc/ssh
/etc/ssh/ssh_config already exists, install will not overwrite
/etc/ssh/sshd_config already exists, install will not overwrite
/etc/ssh/moduli already exists, install will not overwrite
/usr/local/sbin/sshd -t -f /etc/ssh/sshd_config

# 先检查是否正常安装完成sshd
/usr/local/sbin/sshd -V
# 替换系统二进制链接
ln -sf /usr/local/sbin/sshd /usr/sbin/sshd

configure: error: PAM headers not found

rpm -qa | grep pam-devel

sudo yum install pam-devel-1.1.8-23.el7.x86_64.rpm

configure: error: *** zlib.h missing - please install first or check config.log ***

# 安装zlib
sudo yum localinstall zlib-devel-1.2.7-18.el7.x86_64.rpm
sudo yum localinstall pam-1.1.8-23.el7.x86_64.rpm

configure: error: *** working libcrypto not found, check config.log

sudo yum localinstall openssl-devel-1.0.2k-19.el7.x86_64.rpm -y

Error: Package: 1:openssl-devel-1.0.2k-19.el7.x86_64 (/openssl-devel-1.0.2k-19.el7.x86_64)
           Requires: openssl-libs(x86-64) = 1:1.0.2k-19.el7
           Installed: 1:openssl-libs-1.0.2k-16.el7.x86_64 (@anaconda)
               openssl-libs(x86-64) = 1:1.0.2k-16.el7
 You could try using --skip-broken to work around the problem
** Found 1 pre-existing rpmdb problem(s), 'yum check' output follows:
pam-devel-1.1.8-23.el7.x86_64 has missing requires of pam(x86-64) = ('0', '1.1.8', '23.el7')

sudo yum localinstall openssl-libs-1.0.2k-19.el7.x86_64.rpm -y

@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@         WARNING: UNPROTECTED PRIVATE KEY FILE!          @
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
Permissions 0640 for '/etc/ssh/ssh_host_rsa_key' are too open.
It is required that your private key files are NOT accessible by others.
This private key will be ignored.
Unable to load host key "/etc/ssh/ssh_host_rsa_key": bad permissions
Unable to load host key: /etc/ssh/ssh_host_rsa_key
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@         WARNING: UNPROTECTED PRIVATE KEY FILE!          @
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
Permissions 0640 for '/etc/ssh/ssh_host_ecdsa_key' are too open.
It is required that your private key files are NOT accessible by others.
This private key will be ignored.
Unable to load host key "/etc/ssh/ssh_host_ecdsa_key": bad permissions
Unable to load host key: /etc/ssh/ssh_host_ecdsa_key
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@         WARNING: UNPROTECTED PRIVATE KEY FILE!          @
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
Permissions 0640 for '/etc/ssh/ssh_host_ed25519_key' are too open.
It is required that your private key files are NOT accessible by others.
This private key will be ignored.
Unable to load host key "/etc/ssh/ssh_host_ed25519_key": bad permissions
Unable to load host key: /etc/ssh/ssh_host_ed25519_key
sshd: no hostkeys available -- exiting

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

sed -i 's/^GSSAPIAuthentication yes/#&/' /etc/ssh/sshd_config
sed -i 's/^GSSAPICleanupCredentials yes/#&/' /etc/ssh/sshd_config
# 测试发现9.7的配置需要注释下列行
sed -i 's/^GSSAPICleanupCredentials no/#&/' /etc/ssh/sshd_config

HostkeyAlgorithms +ssh-rsa
# 9.8之后使用这个
HostKeyAlgorithms=+ssh-rsa
PubkeyAcceptedAlgorithms +ssh-rsa

iptables -I INPUT 1 -p tcp --dport 23  -j ACCEPT -m comment --comment "放行23端口"

ln -sf /usr/local/sbin/sshd /usr/bin/sshd

sshd: error while loading shared libraries: libcrypto.so.1.1: cannot open shared object file: Permission denied

# libcrypto.so.1.1
删除libcrypto.so.1.1，然后拷贝其他正常主机的文件到这这里
检查文件权限，链接的话查看源文件权限

# 将用户踢下线
who
pkill -kill -t pts/1

etc/pam.d/sshd