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vsftpd frequently asked questions


发布日期:2018年08月25日
 
vsftpd frequently asked questions

Q) Can I restrict users to their home directories?

A) Yes You are probably after the setting:

chroot_local_user=YES

Q) Does vsftpd support a limit on the number of users connected?

A) Yes indirectly vsftpd is an inetdbased service If use the popular

xinetd as your inetd this supports perservice perIP connection limits

There is an example of this in the EXAMPLE directory

A) If you run vsftpd in standalone mode with the setting listen=YES then

you can investigate the setting (eg):

max_clients=

Q) Help! Im getting the error message refusing to run with writable anonymous

root

A) vsftpd is protecting against dangerous configurations The cause of this

message is usually dodgy ownership of the ftp home directory The home

directory should NOT be owned by the ftp user itself Neither should it

be writable by the ftp user A way to fix this is:

chown root ~ftp; chmod w ~ftp

Q) Help! Im getting the error message str_getpwnam

A) The most likely cause of this is that the nobody user does not exist on

your system vsftpd needs this user to run bits of itself with no privilege

Q) Help! Local users cannot log in

A) There are various possible problems

A) By default vsftpd disables any logins other than anonymous logins Put

local_enable=YES in your /etc/nf to allow local users to log in

A) vsftpd tries to link with PAM (Run ldd vsftpd and look for libpam to

find out whether this has happened or not) If vsftpd links with PAM then

you will need to have a PAM file installed for the vsftpd service There is

a sample one for RedHat systems included in the RedHat directory put it

under /etc/pamd

A) If vsftpd didnt link with PAM then there are various possible issues Is

the users shell in /etc/shells? If you have shadowed passwords does your

system have a shadowh file in the include path?

A) If you are not using PAM then vsftpd will do its own check for a valid

user shell in /etc/shells You may need to disable this if you use an invalid

shell to disable logins other than FTP logins Put check_shell=NO in your

/etc/nf

Q) Help! Uploads or other write commands give me Unknown command

A) By default write commands including uploads and new directories are

disabled This is a security measure To enable writes put write_enable=YES

in your /etc/nf

Q) Help! What are the security implications referred to in the

chroot_local_user option?

A) Firstly note that other ftp daemons have the same implications It is a

generic problem

The problem isnt too severe but it is this: Some people have FTP user

accounts which are not trusted to have full shell access If these

accounts can also upload files there is a small risk A bad user now has

control of the filesystem root which is their home directory The ftp

daemon might cause some config file to be read eg /etc/some_file With

chroot() this file is now under the control of the user vsftpd is

careful in this area But the systems libc might want to open locale

config files or other settings

Q) Help! Uploaded files are appearing with permissions rw

A) Depending on if this is an upload by a local user or an anonymous user

use local_umask or anon_umask to change this For example use

anon_umask= to give anonymously uploaded files permissions

rwrr Note that the before the is important

Q) Help! How do I integrate with LDAP users and logins?

A) Use vsftpds PAM integration to do this and have PAM authenticate against

an LDAP repository

Q) Help! Does vsftpd do virtual hosting setups?

A) Yes If you integrate vsftpd with xinetd you can use xinetd to bind to

several different IP addresses For each IP address get xinetd to launch

vsftpd with a different config file This way you can get different behaviour

per virtual address

A) Alternatively run as many copies as vsftpd as necessary in standalone

mode Use listen_address=xxxx to set the virtual IP

Q) Help! Does vsftpd support virtual users?

A) Yes via PAM integration Set guest_enable=YES in /etc/nf This

has the effect of mapping every nonanonymous successful login to the local

username specified in guest_username Then use PAM and (eg) its pam_userdb

module to provide authentication against an external (ie non/etc/passwd)

repository of users

Note currently there is a restriction that with guest_enable enabled local

users also get mapped to guest_username

There is an example of virtual users setup in the EXAMPLE directory

Q) Help! Does vsftpd support different settings for different users?

A) Yes in a very powerful way Look at the setting user_config_dir in the

manual page

Q) Help! Can I restrict vsftpd data connections to a specific range of ports?

A) Yes See the config settings pasv_min_port and pasv_max_port

Q) Help! Im getting the message OOPS: chdir

A) If this is for an anonymous login check that the home directory for the

user ftp is correct If you are using the config setting anon_root check

that is correct too

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