折腾vsftp。。。

500 OOPS: cannot change directory:/home/*******”处理方式

1、vsftpd本地用户不能登录问题的解决:
     打开/etc/selinux/config

将selinux=enforcing或permissive改成disabled。

重启vsftp服务!

2、 用户是否被 vsftpd 限制登录, 比如用户名在 /etc/ftpusers 中,并被阻止登录了。

3、 vsftpd.conf 中是否打开了pam认证的选项 (自己编译安装的时候常因为这个出错) (看vsftpd.conf中是否有pam_service_name=ftp或vsftpd.到底是哪个要看。
PAM模块的服务文件/etc/pam.d下是谁.我的是ftp且它的配置如下:

#%PAM-1.0
auth required /lib/security/pam_listfile.so item=user sense=deny file=/etc/ftpusers onerr=succeed
auth required /lib/security/pam_unix.so shadow nullok
auth required /lib/security/pam_shells.so
account required /lib/security/pam_unix.so
session required /lib/security/pam_unix.so
如果/etc/ftpusers有的用户将被deny

4、 相关文件夹和文件是否有权限：

关于“vsftpd 部分本地用户不能登录，部分可以”的问题，
系统中原来就有的本地帐号都不能登录，我的/etc/vsftpd/vsftpd.conf文件的配置如下：

local_enable=YES
write_enable=YES
chroot_local_user=YES
pam_service_name=vsftpd
/etc/pam.d/vsftpd存在且正常。

登录时错误信息都是一样的：
500 OOPS: cannot change directory:/home/xxxx
Login failed.
421 Service not available, remote server has closed connection

他们的home目录都是/home/xxxx。/home和/home/xxxx的权限都是755。
以上这些帐号都不能ftp登录，这些都是平常经常使用的，可以用shell登录的。

我新创建了一个xxx帐号
# useradd xxx –G lzh -d /tmp/xxx
能ftp登录，他的home为/tmp/xxx,在/分区上。而/home我是mount到/dev/hda9上的。
#mount
/dev/hdb1 on / type ext3 (rw)
/dev/hda9 on /home type ext2 (rw)

所以，我猜想：是否是由于/home分区的原因，而造成“主目录在/home分区的帐号”都不能登录呢？

为了验证以上设想，我试着再创建了一个帐号
useradd –m lzh
/home, /home/lzh 的权限都是755。

lzh ftp登录失败。
500 OOPS: cannot change directory:/home/usr3
Login failed.
421 Service not available, remote server has closed connection

至此，我觉得可以确定是由于/home分区的原因，而造成“主目录在/home分区的帐号”都不能登录。

参考文章：
I finished my second upgrade to Fedora Core 4. Not everything is ironed out yet with the build of course. But one thing is for sure a lot has happened to the RedHat I knew before.

I must say of all the changes, for me the nicest addition is the new SELinux extensions. For deep background on the reasons for and theory of SELinux read, The Inevitability of Failure: The Flawed Assumption of Security in Modern Computing Environments

The more I work with SELinux the more I realize I need to know about it, and how exactly it does all its stuff. It certainly changes things relating to users, directories and access. As I am starting to learn it, I’m sure I’m doing things the hard-way.

The major difference, so far for me, in Red Hat’s SELinux is the way ftp is handled. vsftpd is still the server which is great. However, it seems to be designed to run as a daemon rather than invoked via xinet.d. If you grab a working copy of the xinet.d file for vsftpd you can invoke it via xinet.d wrapper. I did my first server upgrade in this manner. The current one I am trying as a daemon. I certainly think I will miss some of the features that the xinet.d wrapper brings, and may yet return to it.

Of all the issues I saw most notable is if you want to enable chroot directory’s outside of the normal /home/xxx vsftpd. These will fail with a

500 OOPS: cannot change directory: /mnt/xxxxx

I was able to use ftp if I logged in with an account with a directory in /home, but once I set a user account to have a home drive outside of /home (in this case on a mounted secondary disk) vsftpd barfs the above.

I found information at the NSA that indicates you can disable SELinux protection of the ftp daemon.

setsebool -P ftpd_disable_trans 1

This seems a bit drastic. It certainly works for now though.

I think ultimately the issue resides with policies, but as SELinux policies are new to me, it will take time before it all gets sorted out. As I spend time with the new SELinux extensions in Fedora Core 4 I will keep you updated on my thoughts and configuration lessons.

解决办法：
# setsebool ftpd_disable_trans 1

# service vsftpd restart

在ssh输入命令：
setsebool ftpd_disable_trans 1
为避免每次开机都要作这个操作，可在setsebool命令后面加上-P选项，使改动永久有效。
service vsftpd restart

解决方法如下,需要将capability模块加载，
手动加载模块：
# modprobe capability
或者编译进内核:
CONFIG_SECURITY_CAPABILITIES: This enables the “default” Linux capabilities functionality.
If you are unsure how to answer this question, answer Y.
Symbol: SECURITY_CAPABILITIES [=y]
Prompt: Default Linux Capabilities
Defined at security/Kconfig:56
Depends on: SECURITY
Location:
-> Security options
-> Enable different security models (SECURITY [=y]

 

关于vsftp碰到的问题对折腾*nix service的总结[其实就是*nix的保护机制]：

1、如果开了selinux，首先排除这个。

2、配置不允许（基本就是*nix提供的那一堆配置文件），unix编程艺术提到最高境界就是玩这些配置文件。

3、文件系统的保护机制（文件系统对目录和文件的读写执行权限的控制）