# yum install gcc 
# yum install openssl-devel 
# yum install pam-devel 
# yum install rpm-build 

It certainly doesn’t hurt to make the GPG check a habit: 

# wget http://ftp.yz.yamagata-u.ac.jp/pub/network/security/OpenSSH/portable/openssh-5.2p1.tar.gz 
# wget http://ftp.yz.yamagata-u.ac.jp/pub/network/security/OpenSSH/portable/openssh-5.2p1.tar.gz.asc 
# wget -O- http://ftp.yz.yamagata-u.ac.jp/pub/network/security/OpenSSH/portable/DJM-GPG-KEY.asc | gpg –-import 
# gpg openssh-5.2p1.tar.gz.asc 
gpg: Signature made Mon 23 Feb 2009 01:18:28 AM CET using DSA key ID 86FF9C48 
gpg: Good signature from "Damien Miller (Personal Key) " 
gpg: WARNING: This key is not certified with a trusted signature! 
gpg: There is no indication that the signature belongs to the owner. 
Primary key fingerprint: 3981 992A 1523 ABA0 79DB FC66 CE8E CB03 86FF 9C48 

Prepare, build and install the RPM. Disable the building of GUI components in the spec file.  
We don’t need these on a server: 

# tar zxvf openssh-5.2p1.tar.gz 
# cp openssh-5.2p1/contrib/redhat/openssh.spec /usr/src/redhat/SPECS/ 
# cp openssh-5.2p1.tar.gz /usr/src/redhat/SOURCES/ 
# cd /usr/src/redhat/SPECS 
# perl -i.bak -pe 's/^(%define no_(gnome|x11)_askpass)\s+0$/$1 1/' openssh.spec 
# rpmbuild -bb openssh.spec 
# cd /usr/src/redhat/RPMS/`uname -i` 
# ls -l 
-rw-r--r-- 1 root root 275808 Feb 27 08:08 openssh-5.2p1-1.x86_64.rpm 
-rw-r--r-- 1 root root 439875 Feb 27 08:08 openssh-clients-5.2p1-1.x86_64.rpm 
-rw-r--r-- 1 root root 277714 Feb 27 08:08 openssh-server-5.2p1-1.x86_64.rpm 
# rpm -Uvh openssh*rpm 
Preparing... ########################################### [100%] 
1:openssh ########################################### [ 33%] 
2:openssh-clients ########################################### [ 67%] 
3:openssh-server ########################################### [100%] 
# service sshd restart 

 
使用主机环境变量 
修改主机 
sshd_config 
PermitUserEnvironment=yes 
用户目录下 
创建 .ssh/environment 
添加路径 PATH=/usr/sbin/:$PATH 

 
ssh-keygen -t dsa