I'm not shy to admit that I'm new to security, but I am making my best attempt at keeping my servers safe. I'm running vsftpd and I've read that passive mode should be used instead of active mode (or PORT mode) instead due to securtity issues. The only problem I have with this is that in order to use passive mode, I need extra ports open on my router.
This is assuming that only forwarding used ports to the server is a good idea (ports 21, 22, 80, 110 ...). All of the others I deny. However, if I have to now forward around 1000 ports to my server, that might not have a service attached, in order to use passive mode?
Is this correct? Wouldn't this be a security issue to worry about? Would I have to put my linux machine past the router and setup a linux firewall to protect my server? Are unused ports open to the public a security hazard?
-M
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Or, to summarize, Passive is solves security problems for the client but creates them for the server.
The bottom line is that FTP was one of the first IP based user-level applications, and it's more than showing its age.
Aside from scp/sftp, you might also consider HTTP or HTTP/S. Yes, you can use HTTP to upload files. There are some good Perl scripts floating around for automating this if you search for them.
>only alow anonymous read-only access
I got this.
>only accounts whose usernames & passwords don't correspond to Linux accounts
I have this as well.
>FTP sessions must be chrooted into FTP only directories
And I am chrooting them into their own directories.
I don't currently have the machine on a local firewall (as it is the only machine on the local network), but perhaps it should be something I implement anyway. I will also check out Tripwire for some added security.
Thanks for the help,
-M
I am running Proftp, and shorewall firewall with the help of webmin. what you can do is set up a range of ports on the ftp server:
PassivePorts 60000 62000
And include this range in the firewall rules
60000:62000
You also need a ftp client that can let you target these port
http://www.smartftp.com
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by: jleviePosted on 2003-09-12 at 20:30:19ID: 9350582
For passive mode to work to a server behind a firewall ports 21/TCP & 1024-63553/TCP must be open for inbound connections. There's a complete discussion of how ACTIVE & PASSIVE modes work at http://slacksite.com/other
If using a secure protocol isn't an option, my recommendation is that the FTP server only alow anonymous read-only access or that it be configured with FTP only accounts whose usernames & passwords don't correspond to Linux accounts. And all of those FTP sessions must be chrooted into FTP only directories. I'd further recommend that an FTP server be especially hardened, that it run a very restrictive local host based IPtables firewall, and that it have a properly configured copy of Tripwire running.