1.下载最新的openssh包
2.升级openssh之前要先打开服务器telnet，通过telnet登录服务器，因为升级过程中会导致ssh暂时不能用
打开linux telnet服务：
查看telnet是否已经安装：
rpm -qa|grep telnet
telnet-0.17-48.el6.x86_64
telnet-server-0.17-48.el6.x86_64
如果没有安装，通过yum安装
[root@leotest ~]# yum install telnet
[root@leotest ~]# yum install telnet-server
启动telnet服务：
编辑telnet文件，将disable改成no
[root@leotest xinetd.d]# vi /etc/xinetd.d/telnet
# default: on
# description: The telnet server serves telnet sessions; it uses \
# unencrypted username/password pairs for authentication.
service telnet
{
flags = REUSE
socket_type = stream
wait = no
user = root
server = /usr/sbin/in.telnetd
log_on_failure += USERID
disable = no
}
重启xinetd服务：
service xinetd restart
or:
/etc/rc.d/init.d/xinetd restart
通过telnet连接服务器：
[c:\~]$ telnet 192.168.5.5
Connecting to 192.168.5.5:23...
Connection established.
To escape to local shell, press 'Ctrl+Alt+]'.
Red Hat Enterprise Linux Server release 6.8 (Santiago)
Kernel 2.6.32-642.el6.x86_64 on an x86_64
login: test
Password:
[test@leotest ~]$
由于默认telnet只能连接普通用户，所以需要登录普通用户之后跳转到root用户
3.备份原openssh相关文件：
cp /usr/sbin/sshd /usr/sbin/sshd.bak
cp /etc/ssh/ssh_config /etc/ssh/ssh_config.bak
cp /etc/ssh/sshd_config /etc/ssh/sshd_config.bak
cp /etc/ssh/moduli /etc/ssh/moduli.bak
Note:删除掉下面三个文件，否则安装的时候会报错：
/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
rm /etc/ssh/ssh_config -fr
rm /etc/ssh/sshd_config -fr
rm /etc/ssh/moduli -fr
yum install pam-devel
yum install zlib-devel
yum install openssl-devel
4.解压并安装openssh
[root@leotest softs]# tar -zxvf openssh-7.4p1.tar.gz
[root@leotest softs]# ls
openssh-7.4p1 openssh-7.4p1.tar.gz openssh-7.4p1-vs-openbsd.diff.gz
[root@leotest softs]# cd openssh-7.4p1
[root@leotest openssh-7.4p1]#./configure --prefix=/usr/local/openssh --sysconfdir=/etc/ssh --with-pam --with-md5-passwords --mandir=/usr/share/man
### configure: error: *** zlib.h missing – please install first or check config.log
#yum install zlib-devel
###configure: error: *** Can’t find recent OpenSSL libcrypto (see config.log for details) ***
#yum install openssl openssl-devel
重新编译：
重新编译前要先清理之前的编译信息：
make clean
ldconfig
[root@leotest openssh-7.4p1]# ./configure --prefix=/usr/local/openssh --sysconfdir=/etc/ssh --with-pam --with-md5-passwords --mandir=/usr/share/man
OpenSSH has been configured with the following options:
User binaries: /usr/bin
System binaries: /usr/sbin
Configuration files: /etc/ssh
Askpass program: /usr/libexec/ssh-askpass
Manual pages: /usr/share/man/manX
PID file: /var/run
Privilege separation chroot path: /var/empty
sshd default user PATH: /usr/bin:/bin:/usr/sbin:/sbin
Manpage format: doc
PAM support: no
OSF SIA support: no
KerberosV support: no
SELinux support: no
Smartcard support:
S/KEY support: no
MD5 password support: no
libedit 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: rlimit
Host: x86_64-pc-linux-gnu
Compiler: gcc
Compiler flags: -g -O2 -Wall -Wpointer-arith -Wuninitialized -Wsign-compare -Wformat-security -Wno-pointer-sign -fno-strict-aliasing -D_FORTIFY_SOURCE=2 -ftrapv -fno-builtin-memset -fstack-protector-all -fPIE
Preprocessor flags:
Linker flags: -Wl,-z,relro -Wl,-z,now -Wl,-z,noexecstack -fstack-protector-all -pie
Libraries: -lcrypto -lrt -ldl -lutil -lz -lcrypt -lresolv
make && make install
/etc/init.d/sshd restart
5.覆盖旧的文件
cp -p /softs/openssh-7.4p1/contrib/redhat/sshd.init /etc/init.d/sshd
chmod u+x /etc/init.d/sshd
chkconfig --add sshd
cp /usr/local/openssh/sbin/sshd /usr/sbin/sshd
[root@pttlstydb openssh-7.4p1]# cp /usr/local/openssh/sbin/sshd /usr/sbin/sshd
cp: overwrite `/usr/sbin/sshd'? y
cp: cannot create regular file `/usr/sbin/sshd': Text file busy
文件正在被使用
[root@pttlstydb openssh-7.4p1]# ps -ef|grep sshd
root 14111 1 0 10:05 ? 00:00:00 sshd: root@pts/0
root 14865 1 0 10:22 ? 00:00:00 sshd: root@notty
root 24182 14779 0 10:30 pts/1 00:00:00 grep sshd
[root@pttlstydb openssh-7.4p1]# kill -9 14865
[root@pttlstydb openssh-7.4p1]# ps -ef|grep sshd
root 24227 14779 0 10:31 pts/1 00:00:00 grep sshd
重新覆盖：
cp /usr/local/openssh/bin/ssh /usr/bin/ssh
[root@leotest openssh-7.4p1]# service sshd restart
Stopping sshd: [ OK ]
ssh-keygen: illegal option -- A
usage: ssh-keygen [options]
Options:
cat /etc/init.d/sshd
start()
{
# Create keys if necessary
/usr/bin/ssh-keygen -A
if [ -x /sbin/restorecon ]; then
/sbin/restorecon /etc/ssh/ssh_host_key.pub
/sbin/restorecon /etc/ssh/ssh_host_rsa_key.pub
/sbin/restorecon /etc/ssh/ssh_host_dsa_key.pub
/sbin/restorecon /etc/ssh/ssh_host_ecdsa_key.pub
fi
echo -n $"Starting $prog:"
$SSHD $OPTIONS && success || failure
RETVAL=$?
[ $RETVAL -eq 0 ] && touch /var/lock/subsys/sshd
echo
}
因为默认低版本的ssh-keygen没有-A参数
解决方法：
cp /usr/local/openssh/bin/ssh-keygen /usr/bin/ssh-keygen
重启sshd服务：
[root@leotest ssh]# service sshd restart
Stopping sshd: [ OK ]
Starting sshd: [ OK ]
Starting sshd:/etc/ssh/sshd_config line 81: Unsupported option GSSAPIAuthentication
/etc/ssh/sshd_config line 83: Unsupported option GSSAPICleanupCredentials
原因：新版本的openssh不支持以上参数，需要修改sshd的配置文件
[root@leotest openssh-7.4p1]# vi /etc/ssh/sshd_config
##去掉前面的注释，允许root通过ssh登录
PermitRootLogin yes
##注释掉下面三个参数
#GSSAPIAuthentication yes
#GSSAPICleanupCredentials yes
#UsePAM yes
##在文件末尾加上如下信息，否则还是无法通过ssh登录linux：
导致此问题的原因是ssh升级后，为了安全，默认不再采用原来一些加密算法，我们手工添加进去即可。
Ciphers aes128-cbc,aes192-cbc,aes256-cbc,aes128-ctr,aes192-ctr,aes256-ctr,3des-cbc,arcfour128,arcfour256,arcfour,blowfish-cbc,cast128-cbc
MACs hmac-md5,hmac-sha1,umac-64@openssh.com,hmac-ripemd160,hmac-sha1-96,hmac-md5-96
KexAlgorithms diffie-hellman-group1-sha1,diffie-hellman-group14-sha1,diffie-hellman-group-exchange-sha1,diffie-hellman-group-exchange-sha256,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group1-sha1,curve25519-sha256@libssh.org
6.重启sshd服务,测试ssh连接服务器
service sshd restart
[c:\~]$ ssh 192.168.5.5
Connecting to 192.168.5.5:22...
Connection established.
To escape to local shell, press 'Ctrl+Alt+]'.
Last login: Tue Dec 27 00:22:10 2016 from 192.168.5.2
[root@leotest ~]# ssh -V
OpenSSH_7.4p1, OpenSSL 1.0.1e-fips 11 Feb 2013
7.禁用telnet
[root@leotest ~]# vi /etc/xinetd.d/telnet
# default: on
# description: The telnet server serves telnet sessions; it uses \
# unencrypted username/password pairs for authentication.
service telnet
{
flags = REUSE
socket_type = stream
wait = no
user = root
server = /usr/sbin/in.telnetd
log_on_failure += USERID
disable = yes
}
停掉xinetd服务：
[root@leotest ~]# service xinetd stop
Stopping xinetd: [ OK ]
停掉开机自启动：
[root@leotest ~]# chkconfig --list xinetd
xinetd 0:off 1:off 2:off 3:on 4:on 5:on 6:off
[root@leotest ~]# chkconfig xinetd off
[root@leotest ~]# chkconfig --list xinetd
xinetd 0:off 1:off 2:off 3:off 4:off 5:off 6:off
升级后问题解决：
通过winscp登录linux报错，解决方法如下：
[root@leotest ~]# vi /etc/ssh/sshd_config
# override default of no subsystems
#Subsystem sftp /usr/libexec/openssh/sftp-server
Subsystem sftp internal-sftp
将原来的注释掉，改成下面的internal-sftp
重启sshd服务：
service sshd restart
