Re: no ip forged-source-address
"daniel" == Daniel Senie <dts@senie.com> writes: daniel> If the government or other large buyers require network-wide daniel> ingress filtering in any supplier they buy from (something I daniel> suggested to the folks at eBay, Schwab, etc. in our phone daniel> calls after the attacks a few years ago), or if there were daniel> legal incentive, there might be a chance ISPs would find a daniel> financial motive to implement BCP 38. As it is, there's no daniel> incentive, so the path of least resistance is to do nothing. I find it interesting that you suggest that the legal incentive should be toward having the ISPs come up with a magic solution and not toward having the customers do egress filtering at the edge(s) of their network and actually perform something resembling security on the hosts on their networks. After all, it is not usually a security failing of the ISP that causes a DoS or DDoS attack, but utter incompetence or neglect by someone at the edge of the network. The problem is that it's those same people who have the money needed to keep the ISPs in business. Unless all ISPs decided to hold the customers responsible, they'd just move to another ISP. I'm not saying I don't think ISPs should filter where feasible, I'm just saying that if we're going to hold someone responsible, it should be the people who are responsible, not the people who are convenient. but my opinions are probably worthless, Michael
At 12:09 PM 10/30/2002, you wrote:
"daniel" == Daniel Senie <dts@senie.com> writes:
daniel> If the government or other large buyers require network-wide daniel> ingress filtering in any supplier they buy from (something I daniel> suggested to the folks at eBay, Schwab, etc. in our phone daniel> calls after the attacks a few years ago), or if there were daniel> legal incentive, there might be a chance ISPs would find a daniel> financial motive to implement BCP 38. As it is, there's no daniel> incentive, so the path of least resistance is to do nothing.
I find it interesting that you suggest that the legal incentive should be toward having the ISPs come up with a magic solution and not toward having the customers do egress filtering at the edge(s) of their network and actually perform something resembling security on the hosts on their networks.
What I suggested was a financial OR legal incentive.
After all, it is not usually a security failing of the ISP that causes a DoS or DDoS attack, but utter incompetence or neglect by someone at the edge of the network.
That's a question of perspective. Arguably both the ISP and the end user are responsible. The ISP is often in the role of managing the CPE router, and thereby has control over the router where ingress/egress filtering is most easily implemented with simple access control lists.
The problem is that it's those same people who have the money needed to keep the ISPs in business. Unless all ISPs decided to hold the customers responsible, they'd just move to another ISP.
Or unless customers refuse to buy from anyone who doesn't do ingress filtering, resulting in a financial incentive for the ISP.
I'm not saying I don't think ISPs should filter where feasible, I'm just saying that if we're going to hold someone responsible, it should be the people who are responsible, not the people who are convenient.
I find it interesting that some ISPs have no trouble taking care of ingress filtering, while others bellyache about how hard and expensive it is. Another nanog participant commented ATT implemented this starting in 1995. A UUNet person was the most vocal opponent to the draft that became RFC 2267 (over concern that the Cisco 7000's in use then would not handle the load). Six years later, ATT's network seems to do OK. Did UUNet ever do anything about it? Buy gear sized properly to do it? UUNet gives away 2610's with leased lines. Do they come pre-configured to do ingress filtering even? The question for the ISP is how it will defend itself when summoned to court. The ISP had the tools to ensure spoof attacks could not come from its network, yet chose not to. The customer likely would also face the negligence charge. The plaintiff would be the customer of another ISP whose business was severely injured. The question is whether you want to, in court, tell the judge "my customer was an idiot. Blame them, it's not my fault." You might even get away with it, but I suspect you would lose your customer base pretty quickly thereafter. The S in ISP stands for SERVICE. You're providing a service to your customers. Helping those customers stay out of trouble, whether it's by selling them a firewall service, or managing their CPE router, or just providing ingress filtering, is part of what service is about. I'm not surprised that major backbone providers still complain about ingress filtering. I am a bit surprised no lawsuits have get cited BCP 38.
I was trying to keep my mouth shut... but alas that was too tough ;( First, the ip addresses used in the attack are completely disconnected from the problem of the attack. If you get attacked, its really not relevant what ips are used, spoofed or not someone needs to stop it for you. The real problem that needs to be addressed is 'how to make the attacks stop' in the first place. Anyway, on to the comments :) On Wed, 30 Oct 2002, Daniel Senie wrote:
At 12:09 PM 10/30/2002, you wrote:
"daniel" == Daniel Senie <dts@senie.com> writes:
daniel> If the government or other large buyers require network-wide daniel> ingress filtering in any supplier they buy from (something I daniel> suggested to the folks at eBay, Schwab, etc. in our phone daniel> calls after the attacks a few years ago), or if there were daniel> legal incentive, there might be a chance ISPs would find a daniel> financial motive to implement BCP 38. As it is, there's no daniel> incentive, so the path of least resistance is to do nothing.
I find it interesting that you suggest that the legal incentive should be toward having the ISPs come up with a magic solution and not toward having the customers do egress filtering at the edge(s) of their network and actually perform something resembling security on the hosts on their networks.
What I suggested was a financial OR legal incentive.
After all, it is not usually a security failing of the ISP that causes a DoS or DDoS attack, but utter incompetence or neglect by someone at the edge of the network.
That's a question of perspective. Arguably both the ISP and the end user are responsible. The ISP is often in the role of managing the CPE router, and thereby has control over the router where ingress/egress filtering is most easily implemented with simple access control lists.
Wow, this is an overreaching assumption you are making. There are quite a few ISP's that manage a small minority of their customers. I'd think that number at UUNET, for example, manages less than 1% of its customer CPE. Sprint is apparently managing a bit more, given that almost all sprintlink customers I talked to have managed cpe... ATT I don't know about for this argument. The point here is that assuming that "all isps manage their customer's cpe" isn't safe.
I'm not saying I don't think ISPs should filter where feasible, I'm just saying that if we're going to hold someone responsible, it should be the people who are responsible, not the people who are convenient.
I find it interesting that some ISPs have no trouble taking care of ingress filtering, while others bellyache about how hard and expensive it is. Another nanog participant commented ATT implemented this starting in 1995. A UUNet person was the most vocal opponent to the draft that became RFC 2267 (over concern that the Cisco 7000's in use then would not handle the load). Six years later, ATT's network seems to do OK. Did UUNet ever do anything about it? Buy gear sized properly to do it? UUNet gives away 2610's with leased lines. Do they come pre-configured to do ingress filtering even?
Yes, this has been part of the standard customer router config for sometime now... Technically its 'egress' not 'ingress' filters, but the same effect is in place.
The question for the ISP is how it will defend itself when summoned to court. The ISP had the tools to ensure spoof attacks could not come from its network, yet chose not to. The customer likely would also face the
This is entirely NOT the case. The 'tools' being 'urpf' works in limited cases, there are some spectacular failures though. Access-lists on INGRESS at the ISP, except in small ISP examples are a massive scale problem.. not to mention the functionality issues :)
participants (3)
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Christopher L. Morrow -
Daniel Senie -
Michael Lamoureux