RE: How do you keep users from stealing other user's ip??
Hi Mark, The only way you can really lock it down is to statically assign everything (either with a DHCP server that has a table of mac addresses) and maintain an accurate list of mac addresses, and use managed switches that have filtering capabilities. We do this on bridged DSL networks (except for the managed switch part) and it's actually a lot easier to manage that most people think. What you have to do is when a new person hooks into the network, you give them a test IP address, you ping that, get their MAC for that, then hard code that into your DHCP server and tell them to switch over to DHCP to get their permanent address. Once they do that, hard- code the IP address and mac in the router ARP table, and install a filter on the switch port going to them that ignores any traffic that originates from a different MAC than the one that you probed from them. Ted -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Mark Jayson Alvarez Sent: Thursday, March 23, 2006 10:26 PM To: [EMAIL PROTECTED] Subject: How do you keep users from stealing other user's ip?? Good day, We are trying to reorganize our local area network and I need some tips on how you are managing your own lan... We have a vanilla pc router with interface facing our private lan and interface facing the Internet. One problem which we are experiencing right now is that any user from private lan can use any ip address he wants. If he boots his computer with a stolen ip address, the poor owner of that machine(not active at the moment) will give automatically up his ip address to this user. The same scenario for public ip addresses. Basically, we need to track down the users through their ip address.. But this is trivial as of now since anyone can use any ip he wants. Even if there is a solution out there to tie up his mac address to his ip address..(sort of checking the mac first before giving him an ip, possibly through dhcp..) still, users can just download applications which will enable him to change his mac address Now, where thinking about authenticating users before he is allowed to use a particular network service(internet proxy, mail etc.) because I guess it is a clever way of keeping the bad users from doing something bad within your network when after all, the reason why he is plugging his lancard to the network is to use a particular service. However, it still doesn't keep them from playing around and steal other ip addresses or mac addresses and thus denying network access to those legitimate owners. I'm thinking about tying dhcp with authentication, and freeradius comes to mind.. I just need some more tips from you. User's workstations are mixed Windows and *nixes. Some have laptops with wireless interfaces. Any idea how to handle this situations?? Thanks... - New Yahoo! Messenger with Voice. Call regular phones from your PC and save big. ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED] -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.1.385 / Virus Database: 268.3.1/292 - Release Date: 3/24/2006 ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED]
RE: How do you keep users from stealing other user's ip??
You make it sound like they are doing it on purpose. Could it be the lease duration is so short that the ips are going back into the pool before they are truly abandoned by the original user? If you look at the behavior of the MS DHCP server, the lease duration is 8 days (with standard 4 day renewal). If it takes 8 days for it to back into the pool, this should be more than enough time for a user to go home for the weekend, and hopefully get the same ip when they get back to work. I would suggest increasing the lease duration time and see if that stops users from stepping on each others dhcp leases (don't forget, in the typical dhcp-request conversation, the client asks hey, I had x.x.x.x last, is it still available for me? you want the server to be able to say sure). On my freebsd router, the DHCP server came with a 1 hour lease duration (which causes a 30 minute renewal.. IMO this is too fast). Second, you mentioned that users could just download software that would allow them to change their mac address. It sounds like some users have too high a rights assignment, if they are causing mischief like that. Cheers, jonathan -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Ted Mittelstaedt Sent: Sunday, March 26, 2006 4:06 AM To: Mark Jayson Alvarez; [EMAIL PROTECTED] Subject: RE: How do you keep users from stealing other user's ip?? Hi Mark, The only way you can really lock it down is to statically assign everything (either with a DHCP server that has a table of mac addresses) and maintain an accurate list of mac addresses, and use managed switches that have filtering capabilities. We do this on bridged DSL networks (except for the managed switch part) and it's actually a lot easier to manage that most people think. What you have to do is when a new person hooks into the network, you give them a test IP address, you ping that, get their MAC for that, then hard code that into your DHCP server and tell them to switch over to DHCP to get their permanent address. Once they do that, hard- code the IP address and mac in the router ARP table, and install a filter on the switch port going to them that ignores any traffic that originates from a different MAC than the one that you probed from them. Ted -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Mark Jayson Alvarez Sent: Thursday, March 23, 2006 10:26 PM To: [EMAIL PROTECTED] Subject: How do you keep users from stealing other user's ip?? Good day, We are trying to reorganize our local area network and I need some tips on how you are managing your own lan... We have a vanilla pc router with interface facing our private lan and interface facing the Internet. One problem which we are experiencing right now is that any user from private lan can use any ip address he wants. If he boots his computer with a stolen ip address, the poor owner of that machine(not active at the moment) will give automatically up his ip address to this user. The same scenario for public ip addresses. Basically, we need to track down the users through their ip address.. But this is trivial as of now since anyone can use any ip he wants. Even if there is a solution out there to tie up his mac address to his ip address..(sort of checking the mac first before giving him an ip, possibly through dhcp..) still, users can just download applications which will enable him to change his mac address Now, where thinking about authenticating users before he is allowed to use a particular network service(internet proxy, mail etc.) because I guess it is a clever way of keeping the bad users from doing something bad within your network when after all, the reason why he is plugging his lancard to the network is to use a particular service. However, it still doesn't keep them from playing around and steal other ip addresses or mac addresses and thus denying network access to those legitimate owners. I'm thinking about tying dhcp with authentication, and freeradius comes to mind.. I just need some more tips from you. User's workstations are mixed Windows and *nixes. Some have laptops with wireless interfaces. Any idea how to handle this situations?? Thanks... - New Yahoo! Messenger with Voice. Call regular phones from your PC and save big. ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED] -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.1.385 / Virus Database: 268.3.1/292 - Release Date: 3/24/2006 ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED] ___ freebsd-questions
Re: How do you keep users from stealing other user's ip??
Hi, Ok here's our problems. Mostly pertaining to tracking down who is this user eating up our bandwidth or who is this user flooding our network. 1. Users when they want to plug a machine to the network... let's say their own testbeds, they will choose whatever ip they want possibly stealing used ip's. 2. Users workstations are mixed Windows and *nixes. Most windows machines are getting infected with worm from time to time... Some of them are not so skillful enough to clean their own workstations. Given an unmanaged ip allocation, it would also be hard to trace which machines are causing the network congestion. 3. Some users with public workstations and testbeds are eating up bandwidth through file sharing...Still hard to trace this without proper ip allocation management. Erik Nørgaard [EMAIL PROTECTED] wrote: I once set up such a solution in a student house with about 120 users. People had their own private pcs so we couldn't just take away their admin rights on their own pc. Now, question to ask: - Are all users legitimate users? Do users have friends coming in and connect to the network? is it wired or do you have neighbors trying to use the net also? - What is the benefit of stealing another users ip? Do you have limitations on access such as download? Is it to hide behind another user? In our case we had a wired network, so all users was legitimate users, but we had a limitation on download so some users would try to use their neighbors ip to get more quota. What we did was: 1) Static ip assigned with dhcp - people wouldn't need to learn to configure their computer. 2) Static arp table on router, to spoof, one would have to spoof mac-address. 3) Require registration of all hosts owned by the user: To hold users accountable for their hosts. 4) Count traffic per host, up and download, this was done with ipfilter. 5) Make current usage visible, the users could always check their quota and knew when they hit the limit. That way they didn't get surprises and annoyed. This actually worked fine. It was sufficiently complicated to spoof that people wouldn't bother. A different and possibly better way around this would be to limit bandwidth for ports higher than 1023, this is where most file sharing takes place. You can do that with packet filter, I still haven't figured how to effectively implement traffic quotas on packet filter as accounting is not so easy. If your concerns are people trying to hide behind others identity, or unauthorized access such as if you have a wireless lan, then there are two good options: 1) Use authpf with packet filter. This requires the user to authenticate with the firewall to get access. No proxy needed. 2) Let each client establish a VPN to the router, this have the advantage of also encrypting traffic if you have a wireless or non-switched network. Cheers, Erik -- Ph: +34.666334818 web: www.locolomo.org S/MIME Certificate: www.daemonsecurity.com/ca/8D03551FFCE04F06.crt Subject ID: 9E:AA:18:E6:94:7A:91:44:0A:E4:DD:87:73:7F:4E:82:E7:08:9C:72 Fingerprint: 5B:D5:1E:3E:47:E7:EC:1C:4C:C8:3A:19:CC:AE:14:F5:DF:18:0F:B9 - New Yahoo! Messenger with Voice. Call regular phones from your PC and save big. ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED]
Re: How do you keep users from stealing other user's ip??
1. Users when they want to plug a machine to the network... let's 1. say their own testbeds, they will choose whatever ip they want 1. possibly stealing used ip's. Use DHCP, then users do not have to choose an IP, it is given to them. Plus it gives them all parameterstheyneed to configure their machineto acces the network (like netmask, gateway, DNS...) DHCP keeps logs of what IP wasassigne to what machine (for Windows you have the windows name of the machine) so you can track what is what down. If you are dealing with users that have little knowledge and not with hackers (and it seems to be your case) DHCPo will solve 90% of your problems. Olivier ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED]
Re: How do you keep users from stealing other user's ip??
Mark Jayson Alvarez wrote: Hi, Ok here's our problems. Mostly pertaining to tracking down who is this user eating up our bandwidth or who is this user flooding our network. 1. Users when they want to plug a machine to the network... let's say their own testbeds, they will choose whatever ip they want possibly stealing used ip's. 2. Users workstations are mixed Windows and *nixes. Most windows machines are getting infected with worm from time to time... Some of them are not so skillful enough to clean their own workstations. Given an unmanaged ip allocation, it would also be hard to trace which machines are causing the network congestion. 3. Some users with public workstations and testbeds are eating up bandwidth through file sharing...Still hard to trace this without proper ip allocation management. If the problem is that users choose occupied ips by accident rather than by bad will, then use dhcp. Windows users and novices will thank you for not having to deal with the configuration and you can say just plug it in and it works. If you want to make people aware of what it means to be on the network, register their hosts with mac address and have them sign a paper with your AUP. Track changes with arpwatch. Assign a segment of your address space to testbeds, tell people who want to experiment that they choose an ip in that segment. That segment should be blocked or only have access to limited services such as dns, ftp and http. Block all access to port 25 on internet to make sure that mail is sent through your mailserver. Require authentication for smtp. This means that at least you won't spread the viruses that infect the windows clients. Cheers, Erik -- Ph: +34.666334818 web: www.locolomo.org S/MIME Certificate: www.daemonsecurity.com/ca/8D03551FFCE04F06.crt Subject ID: 9E:AA:18:E6:94:7A:91:44:0A:E4:DD:87:73:7F:4E:82:E7:08:9C:72 Fingerprint: 5B:D5:1E:3E:47:E7:EC:1C:4C:C8:3A:19:CC:AE:14:F5:DF:18:0F:B9 ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED]
Re: How do you keep users from stealing other user's ip??
On Mar 23, 2006, at 11:25 PM, Mark Jayson Alvarez wrote: Good day, We are trying to reorganize our local area network and I need some tips on how you are managing your own lan... We have a vanilla pc router with interface facing our private lan and interface facing the Internet. One problem which we are experiencing right now is that any user from private lan can use any ip address he wants. If he boots his computer with a stolen ip address, the poor owner of that machine (not active at the moment) will give automatically up his ip address to this user. The same scenario for public ip addresses. Basically, we need to track down the users through their ip address.. But this is trivial as of now since anyone can use any ip he wants. Even if there is a solution out there to tie up his mac address to his ip address..(sort of checking the mac first before giving him an ip, possibly through dhcp..) still, users can just download applications which will enable him to change his mac address Now, where thinking about authenticating users before he is allowed to use a particular network service(internet proxy, mail etc.) because I guess it is a clever way of keeping the bad users from doing something bad within your network when after all, the reason why he is plugging his lancard to the network is to use a particular service. However, it still doesn't keep them from playing around and steal other ip addresses or mac addresses and thus denying network access to those legitimate owners. I'm thinking about tying dhcp with authentication, and freeradius comes to mind.. I just need some more tips from you. User's workstations are mixed Windows and *nixes. Some have laptops with wireless interfaces. Any idea how to handle this situations?? Why do you have bad users? (I assume this is some sort of company?) Set a policy and punish those that screw around. Most companies I have seen do not give admin privileges to the users so the user cannot change his IP or MAC address and if you force them to use DHCP you can also tie the MAC to the IP. This is not a technical problem per se but an administrative policy problem. Chad --- Chad Leigh -- Shire.Net LLC Your Web App and Email hosting provider chad at shire.net ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED]
Re: How do you keep users from stealing other user's ip??
Mark Jayson Alvarez wrote: Good day, We are trying to reorganize our local area network and I need some tips on how you are managing your own lan... We have a vanilla pc router with interface facing our private lan and interface facing the Internet. One problem which we are experiencing right now is that any user from private lan can use any ip address he wants. If he boots his computer with a stolen ip address, the poor owner of that machine(not active at the moment) will give automatically up his ip address to this user. The same scenario for public ip addresses. Basically, we need to track down the users through their ip address.. But this is trivial as of now since anyone can use any ip he wants. Even if there is a solution out there to tie up his mac address to his ip address..(sort of checking the mac first before giving him an ip, possibly through dhcp..) still, users can just download applications which will enable him to change his mac address Now, where thinking about authenticating users before he is allowed to use a particular network service(internet proxy, mail etc.) because I guess it is a clever way of keeping the bad users from doing something bad within your network when after all, the reason why he is plugging his lancard to the network is to use a particular service. However, it still doesn't keep them from playing around and steal other ip addresses or mac addresses and thus denying network access to those legitimate owners. I'm thinking about tying dhcp with authentication, and freeradius comes to mind.. I just need some more tips from you. User's workstations are mixed Windows and *nixes. Some have laptops with wireless interfaces. Any idea how to handle this situations?? I once set up such a solution in a student house with about 120 users. People had their own private pcs so we couldn't just take away their admin rights on their own pc. Now, question to ask: - Are all users legitimate users? Do users have friends coming in and connect to the network? is it wired or do you have neighbors trying to use the net also? - What is the benefit of stealing another users ip? Do you have limitations on access such as download? Is it to hide behind another user? In our case we had a wired network, so all users was legitimate users, but we had a limitation on download so some users would try to use their neighbors ip to get more quota. What we did was: 1) Static ip assigned with dhcp - people wouldn't need to learn to configure their computer. 2) Static arp table on router, to spoof, one would have to spoof mac-address. 3) Require registration of all hosts owned by the user: To hold users accountable for their hosts. 4) Count traffic per host, up and download, this was done with ipfilter. 5) Make current usage visible, the users could always check their quota and knew when they hit the limit. That way they didn't get surprises and annoyed. This actually worked fine. It was sufficiently complicated to spoof that people wouldn't bother. A different and possibly better way around this would be to limit bandwidth for ports higher than 1023, this is where most file sharing takes place. You can do that with packet filter, I still haven't figured how to effectively implement traffic quotas on packet filter as accounting is not so easy. If your concerns are people trying to hide behind others identity, or unauthorized access such as if you have a wireless lan, then there are two good options: 1) Use authpf with packet filter. This requires the user to authenticate with the firewall to get access. No proxy needed. 2) Let each client establish a VPN to the router, this have the advantage of also encrypting traffic if you have a wireless or non-switched network. Cheers, Erik -- Ph: +34.666334818 web: www.locolomo.org S/MIME Certificate: www.daemonsecurity.com/ca/8D03551FFCE04F06.crt Subject ID: 9E:AA:18:E6:94:7A:91:44:0A:E4:DD:87:73:7F:4E:82:E7:08:9C:72 Fingerprint: 5B:D5:1E:3E:47:E7:EC:1C:4C:C8:3A:19:CC:AE:14:F5:DF:18:0F:B9 ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED]
