A few basic questions about features from a NOOB -
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@Hollander:
Is it that easy to spoof your LAN-ip adress, from, say, Win7? For even kids?
:o
All it takes is access to the device manager where the settings for the network adapter device offers you a field where you can enter the MAC address you want to use instead of the pre-programmed one.
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@Hollander:
For even kids?
Especially for kids! They don't know it might be or should be difficult so they poke around until intil it's done. They've never known a computer that wasn't on the internet or a firewall that couldn't be eventually broken. Also they probably have a lot of friends who are also learning about this stuff and there's literally thousands of pages on the web explaining how to do it. Safer to assume kids know more than you! ;)
Steve
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Especially for kids! …
DHCP, with static mapping based on MAC, with "deny unknown clients", with static ARP. What would be the work-around to get internet access? :-\
EDIT: Cron job for killing states works apparently fine! However, it looks as if states for one of the users were already killed when the firewall went to "BLOCK"… strange...
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I'm not saying that it's impossible to lock down a computer to prevent 'unauthorised' internet access. It's easy enough to put a security policy on a Windows box to prevent users changing the MAC but how many home computers have that?
I'm just saying that most computer literate school age children have probably come up against some sort of web/connection filter at some point and those who are minded to do so have probably looked into ways to get around it. Someone they are friends with will have suggested finding the MAC of a local authorised machine from the ARP table and changing your MAC to it. That friend will then gain popularity for doing so. Everybody wins. Except the network admin/parents!It would be a mistake to assume that just because users are children they will not be familiar with basic networking. It's in their interests to keep you thinking they aren't. ;)
Steve
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@chemlud:
DHCP, with static mapping based on MAC, with "deny unknown clients", with static ARP. What would be the work-around to get internet access? :-\
Exactly what my thinking was and then running the CRON jobs. I am even thinking of VLAN-ing him to keep him completely separate and isolated. I already have him setup on a guest wifi network that is isolated from us. So, now I guess I have to buy a smart or managed switch. The $$$$ keeps flying away! lol
Kind of how it is setup on my DD-WRT router. Again, DD-WRT itself is 50/50 reliable and then there are fixes and new versions and then what was working doesn't work any more. lol I have a love/hate relationship with it. lol
I'm not saying that it's impossible to lock down a computer to prevent 'unauthorised' internet access. It's easy enough to put a security policy on a Windows box to prevent users changing the MAC but how many home computers have that?
I'm just saying that most computer literate school age children have probably come up against some sort of web/connection filter at some point and those who are minded to do so have probably looked into ways to get around it. Someone they are friends with will have suggested finding the MAC of a local authorised machine from the ARP table and changing your MAC to it. That friend will then gain popularity for doing so. Everybody wins. Except the network admin/parents!It would be a mistake to assume that just because users are children they will not be familiar with basic networking. It's in their interests to keep you thinking they aren't. ;)
Steve
Uhhhhh, YEP! lol Been through this. Trust me I am so freaking glad he is 19 now. From the time he was 14 it was a total battle royal. The parental software out there is a joke - Net Nanny, etc., I tried them all! The kids go to forums or chat and learn from each other how to hack it and bypass it. And the sw companies move like molasses when it comes to fixing their bugs. I spent 3 solid months playing email ping pong with Net Nanny actually helping them fix their own darn bugs and I just had had enough. By the time he was 17, I had to go to the extreme level. I literally had the machine locked down and frozen with Deep Freeze by Faronics with only his game folders and a homework folder on a separate isolated HD being the only things on his PC that he could alter. And it worked too! He was so pissed you could see the hate! lol I even had the BIOS locked with a password too.
So now he is a 19 yr old college freshman about to become a sophomore and a full summer ahead of him and I am not going to deal with him PCing into the wee small hours. I will pull the router plug out if I have to and that is in a steel locked cabinet that he definitely can't get to. lol Hence, why I drool over something rock solid and automated to save me the stress.
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Agreed, a separate interface is the way go for real security.
Then put a super cheap switch between the router and the hostile machine. Power that switch from via timer. Done! ;)Steve
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@chemlud:
@Hollander:
Useful, John, thank you for this suggestion ;D
But, as always, I don't understand it: you first kill the states, then they are re-restablished by the system, then you have to kill them again via a cronjob? But won't they be established again then?
Or more fundamentally: shouldnt the firewall schedule take care of this automatically? As in: this is not a bug, it is a feature'? ( ;D )
If you kill the states after a scheduled "end of internet access" the states can't be re-established…
Lately I checked for states after "end of internet" and after the subsequent Cron job to kill all states and found for one of the IPs active states 1.5 hours after the end of internet… How can that happen? :o
I would like to monitor the states via email report, but unfortunately there is no log for the states and I don't know the command to be executed to post the current states of the box.... Can anybody help me out, please? :)
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I showed you the command to list states for an IP, or all of them pfctl -ss
You may need to kill both sides of the state.. When you kill the states, what do you show with the -ss for your host your worried about? You may need to use the -k twice, etc.
I would suggest you read the man on pfctl, I would of assumed that would of been step one after I gave the command example ;)
http://www.openbsd.org/cgi-bin/man.cgi?query=pfctl&sektion=8
NAME
pfctl - control the packet filter (PF) deviceSYNOPSIS
pfctl [-deghnPqrvz] [-a anchor] [-D macro=value] [-F modifier] [-f file]
[-i interface] [-K host | network] [-k host | network | label | id]
[-L statefile] [-o level] [-p device] [-S statefile]
[-s modifier [-R id]] [-t table -T command [address …]]
[-x level] -
Yess, I must confess I started with Linux/BSD last fall, so I'm far from pro… Should invest a little more time, but currently it is a little bit too much around here. I'll do my very best :D
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Huh? From your title of the thread we understand your not a pro ;)
Given a command, with examples that showed listing of states doesn't seem too far reaching to think the person with the interest the function would breeze over the doc for the command given..
I would think the same thing be it a linux/bsd command or a windows cmd.. If I say told you to release your dhcp lease you could use ipconfig /releaseall
Wouldn't you look up the command ipconfig? Not like gave you example pfctl and then expected you to recompile your kernel ;)
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cough I didn't start this thread, I actually hijacked it. cough, cough ::)
… but the pfctl does nicely what it is supposed to do with the mail report. Unfortunately the mail report allows eMails only at full hours (no minutes to be added to the job...). (edit: me idi**, found the jobs in Cron to edit the time of execution ;)). However, very nice indeed!
And I compiled my kernel with the router at the same time :P
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It's absolutely fascinating:
20:00 firewall turns off internet (block rule all IPs and all ports with schedule)
20:02 all states are gone (pfctl -ss | grep <ip>via mail report, and checked by hand)however, as pidgin, thunderbird and firefox are still open on this particular computer:
20:04 states (more than a dozen) to google (993) and to one of these infamous game servers (443) are up again (in both directions):
re2 tcp 74.125.136.16:993 <- 10.xxx.xxx.xxx:38268 ESTABLISHED:ESTABLISHED
re1 tcp 10.xxx.xxx.xxx:38268 -> 83.xxx.xxx.xxx:40101 -> 74.125.136.16:993 ESTABLISHED:ESTABLISHEDor
re2 tcp 216.66.6.120:443 <- 10.xxx.xxx.xxx:37596 ESTABLISHED:ESTABLISHED
re1 tcp 10.xxx.xxx.xxx:37596 -> 83.xxx.xxx.xxx:44266 -> 216.66.6.120:443 ESTABLISHED:ESTABLISHED…for example...
The Cron job to kill all states for this particular local IP doesn't change anything, all states present (again?) 5 minutes after the pfctl -k <ip>command.
Only killing each and every state at once apparently really ends the game(s), so to say.</ip></ip>
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… Or you could issue a pfctl -f state
Which would kill all states - if possible target just his IP.. so doesn't break your connections.
Actually, the correct command to kill all states is
pfctl -F state
(there is an error at the man page for pfctl at openBSD, there it is "states", which actually doesn't work… :-D )
http://www.openbsd.org/cgi-bin/man.cgi?query=pfctl&sektion=8
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The pf in FreeBSD has moved significantly away from that in OpenBSD. Also the pf in pfSense is different to that in the base FreeBSD version so even this page may not be entirely correct. But, yes 'F' appears correct. :)
Steve
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I found the easiest way to avoid all the hassle with killed connections and existing states etc was to take the other approach.
make an alias for IP addresses you want to block called blocked
make a schedule for the hours you want it to work named limitsFirewall rules, LAN tab,
first rule is the antilockout rule
second rule says when the controlled devices ARE allowed on,
allow source blocked schedule limits
third rule is
allow source!blockedworks very well.
PS its trivial to get an app to change the mac address, so its not exactly fullproof. I told my kid that its his reminder , not designed to be full proof.
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…today I found some states (I think it was one of these game IPs) 1.5 hours after the block kicked in and a subsequent pfctl -F state.
I don't believe any longer in any of those firewalls, rules, whatsoever. An open browser is apparently enough to restart the states, no idea how that works...
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Try what I do. I know it works because right on the hour, he walks out of his room and gets a snack every day. If the game he was playing was still working, he would be still in there!.
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"1.5 hours after the block kicked in and a subsequent pfctl -F state."
Your sure your command ran and cleared the states? If pfctl -f or -F, clears the states and your rules don't allow traffic then something is clearly not right in the rules or the states were not cleared would be my guess.
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I have a Cron job to do pfctrl -F state 1 min after the block rule kicks in (allow rules didn't work either and I had to have more than one, due to the general limitations on ports/IPs). An eMail Service says 1 h later:
"This is a periodic report from your firewall
Current report: states >NAME< 21:00
Command output: states (pfctl -ss | grep 10.zzz.yyy.xxx)"
i.e. there are no states, which I checked by hand several times. But half an hour later I found 6-8 states to this notorious ivony.com IP (216.66.6.120). Unfortunately I killed them and took no screenshot in advance…
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Can you post up your rules so we can take a look at what they are and what your trying to do.. I thought you wanted to block his access completely.. Off the top if your saying new states are being created when your trying block them, then your rules are not correct for what your trying to do.
