请教yum使用代理Windows的ISA服务器问题

因为公司统一使用Windows的ISA服务器作为代理服务器，我进入Fedora8（双系统XP＋fedora8,不是用的vmware）之后，配置Mozilla/5.0的代理服务器与端口8080，打开时Mozilla会弹出输入用户名与密码后，能正常浏览网页，但在命令行（GNOME Terminal），使用YUM与wget出现如下错误信息。我与负责ISA服务器的工程师确认，他说我在命令行是没有提交用户名，是匿名的，所以访问被拒绝了，请各位高手指教，不胜感激。谢谢！
[root@xj01-teri ~]# echo $http_proxy
http://user:passwd@firewall.XXXXX.com.cn:8080/

[root@xj01-teri ~]# yum list
Could not retrieve mirrorlist http://mirrors.fedoraproject.org/mirrorlist?repo=rawhide&arch=i386 error was
[Errno 14] HTTP Error 407: Proxy Authentication Required ( The ISA Server requires authorization to fulfill the request. Access to the Web Proxy filter is denied. )
Error: Cannot retrieve repository metadata (repomd.xml) for repository: development. Please verify its path and try again
[root@xj01-teri ~]# wget -c http://example.com/really-big-file.iso
--16:27:37-- http://example.com/really-big-file.iso
=> `really-big-file.iso'
正在解析主机 firewall.XXXXX.com.cn... 10.9.9.14, 10.9.9.15, 10.9.9.17, ...
Connecting to firewall.XXXXX.com.cn|10.9.9.14|:8080... 已连接。
已发出 Proxy 请求，正在等待回应... 407 Proxy Authentication Required ( The ISA Server requires authorization to fulfill the request. Access to the Web Proxy filter is denied. )
16:27:38 错误 407：Proxy Authentication Required ( The ISA Server requires authorization to fulfill the request. Access to the Web Proxy filter is denied. )。