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On Saturday 05 September 2009 11:56:09 Dale wrote: |
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> Hi, |
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> |
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> As some may know already, I recently got DSL. It's not a super fast |
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> connection by broadband standards but it does mean that my box may be |
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> easier to find for a hacker. So, I have a few questions about |
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> security. I think I am OK but want to make sure. |
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> |
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> 1: I have a good root password. It's not something someone would guess |
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> for sure. Nothing related to my history, birthdays or anything. It is |
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> still fairly easy for me to type tho. |
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Good. Also disable root login using sshd |
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> 2: I went to this link: https://www.grc.com/x/ne.dll?bh0bkyd2 |
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> According to that site my ports are in "stealth" mode which is good from |
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> what I understand. |
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That's Gibson. Sometimes he talks sense and has good ideas, but he always |
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rambles. Wheat and chaff. |
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Run "netstat -atnup" and see what's open. Apply brainpower to what you see. |
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Learn how to drive nmap and throw it at localhost. Apply brainpower to what |
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you see. |
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> 3: I have no servers running here. No Apache, MySql, or any of that. |
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> I also have turned off/stopped ssh since I have only one box at the |
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> moment. |
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no services running by default is a sane starting point for personal use. But |
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you will likely need *some* services, so deploy them one by one and audit each |
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one before taking it live. Start them only when you need them. |
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> 4: I'm currently using this kernel: 2.6.25-gentoo-r9 I plan to |
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> upgrade that in the next day or so. |
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Kernel bugs exist of course, but in terms of numbers, it's far easier for |
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someone to access your box using other routes. Like php. |
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Pay attention to kernel bugs but you also have to prioritize by risk factor, |
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so that one is correspondingly lower on the list. |
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> The DSL modem I am using is the Motorola 2210. It seems to be a gateway |
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> thing. I have no router at the moment but if I build a new rig I will |
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> be getting one then. Most likely a Linksys or something. I'll post |
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> here before getting one anyway. ;-) |
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> |
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> Am I missing anything? If you need more info, let me know. I just want |
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> to make sure no one can get into my box without me knowing about it and |
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> getting into mischief. |
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|
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By far the most common attack vector into home machines is users doing stupid |
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things with mail and dodgy links. This is how phishers work. So you need to |
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apply diligence in what you click and where you go. But, you are likely |
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exercising this already. |
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Top of my list is always to lock down things that give shell access. No |
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telnet, no root login, access for specific users only. I use "AllowGroups" in |
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sshd_config a lot - only that group's members may log in and one grep shows |
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you exactly who is in that group. |
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You deal with brute force attacks using packages like fail2ban and denyhosts. |
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The general idea is that if a certain number of failed attempts show up in the |
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logs in a short time, that IP is locked out for a few hours. |
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john the ripper is excellent at finding weak passwords. I don't know how much |
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benefit you will get - having only two users with passwords - but I use it |
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routinely on my servers. There's a certain satisfaction in attending security |
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forum meetings and telling some manager with a stick up his ass that you are |
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the one who trashed his access because you found his password in 38 seconds |
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:-) |
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-- |
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alan dot mckinnon at gmail dot com |
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