Re: Syn flood crashed my LAN
Agreed about ubnt vs tplink vs cisco... most use either broadcom or marvel chipsets Stuart I was sugesting based on rated performance of the chipsets in the datasheets of the managed switch... as opposed to a cheap un managed one the other thing i for got to mention which was part of my advice was that the ability to check counters on each interface can indicate where the packets are being dropped are the being dropped beween switch ports or on the open bas firewall etc On 12 Feb 2018 1:59 PM, "Stuart Henderson"wrote: > On 2018-02-12, Tom Smyth wrote: > > Regards D-Link... I would recommend that you use > > a decent managed switch (based on Tech Specs as opposed > > to Branding, > > you can pick up cost effective ubnt edgeswitches or > > Tplink (fully managed Switches) which would offer linerate switching > > or if you want to have a branded switch get one second hand for best > value > > They're all use one of a couple of pretty similar switch chips anyway. > > Without doing more to figure out *how* it broke I don't think it's possible > to say that one brand is going to react better than another. > > >
Re: Syn flood crashed my LAN
On 2018-02-12, Tom Smythwrote: > Regards D-Link... I would recommend that you use > a decent managed switch (based on Tech Specs as opposed > to Branding, > you can pick up cost effective ubnt edgeswitches or > Tplink (fully managed Switches) which would offer linerate switching > or if you want to have a branded switch get one second hand for best value They're all use one of a couple of pretty similar switch chips anyway. Without doing more to figure out *how* it broke I don't think it's possible to say that one brand is going to react better than another.
Re: Syn flood crashed my LAN
From my seat, he learned that his configuration of PF lacks SYN flooding protection. He also learned that he needs a managed switch: cisco SF and SG series are affordable and deliver ddos protection. Sent from ProtonMail Mobile On Mon, Feb 12, 2018 at 07:22, Bruno Flueckigerwrote: > On 12.02.18 01:26, Martin Hanson wrote: > Hi, > > I have a home network that > is segmented into 3 different zones using a NIC with 4 ports sitting on an > OpenBSD firewall/dhcp server. One port is connected to the Internet (ISP > router) and each of the three others has a D-Link DGS-1005D switch connected > to each. > > So.. > > LAN1 = 192.168.1.0 > LAN2 = 192.168.2.0 > LAN3 = > 192.168.3.0 > > Learning more about networking I wanted to test a SYN flood > so I set up a couple of boxes on LAN1 and LAN3 to flood a box on LAN2. I used > "hping3" with the "S" and "flood" options. > > Running a regular ping in a > terminal I could see how the response time decreased and eventually the box > began to loose packages. > > However after a while it seemed like the entire > internal network went down. > > No box on any LAN could get an IP address > from the DHCP server on the OpenBSD box. > > I eventually rebooted the > OpenBSD box, but that didn't immediately help, and only after powering down > the switches and powering the switches on again, everything worked again. > > > I have been looking through the PF documentation to see if PF somehow blocks > SYN flooding, but I am not using synproxy on any rules. > > What could cause > such a "melt down" of the entire network because of a SYN flood to a box? > > > I suspect that the D-Link switches are pretty bad and maybe are the cause of > the problem? > > I eventually will try again to see if I can determine what's > causing the "melt down", but I want to know if anyone perhaps has experienced > similar results during some testing? > > Many thanks in advance. > > Kind > regards, > > Martin You run a denial of service attack against your home > network. As a result your network denials service. Sounds like you have > proven that syn flooding is an effective denial of service attack in your > network. Yes, your switches cannot handle the amount of traffic you putting > on them. No, your switches are not the problem. Your syn flooding of the > network is causing the problem. Cheers, Bruno -- I really hope this whole > thing works, I won't be able to test everything beforehand
Re: Syn flood crashed my LAN
Regards D-Link... I would recommend that you use a decent managed switch (based on Tech Specs as opposed to Branding, you can pick up cost effective ubnt edgeswitches or Tplink (fully managed Switches) which would offer linerate switching or if you want to have a branded switch get one second hand for best value By the way... if you are doubting the switch (and you dont have tech specs of the switch or you cant monitor it .. or get counters off it ... then there is no doubt ... :) Regards, Tom Smyth On 12 February 2018 at 00:26, Martin Hansonwrote: > Hi, > > I have a home network that is segmented into 3 different zones using a NIC > with 4 ports sitting on an OpenBSD firewall/dhcp server. One port is > connected to the Internet (ISP router) and each of the three others has a > D-Link DGS-1005D switch connected to each. > > So.. > > LAN1 = 192.168.1.0 > LAN2 = 192.168.2.0 > LAN3 = 192.168.3.0 > > Learning more about networking I wanted to test a SYN flood so I set up a > couple of boxes on LAN1 and LAN3 to flood a box on LAN2. I used "hping3" with > the "S" and "flood" options. > > Running a regular ping in a terminal I could see how the response time > decreased and eventually the box began to loose packages. > > However after a while it seemed like the entire internal network went down. > > No box on any LAN could get an IP address from the DHCP server on the OpenBSD > box. > > I eventually rebooted the OpenBSD box, but that didn't immediately help, and > only after powering down the switches and powering the switches on again, > everything worked again. > > I have been looking through the PF documentation to see if PF somehow blocks > SYN flooding, but I am not using synproxy on any rules. > > What could cause such a "melt down" of the entire network because of a SYN > flood to a box? > > I suspect that the D-Link switches are pretty bad and maybe are the cause of > the problem? > > I eventually will try again to see if I can determine what's causing the > "melt down", but I want to know if anyone perhaps has experienced similar > results during some testing? > > Many thanks in advance. > > Kind regards, > > Martin > -- Kindest regards, Tom Smyth Mobile: +353 87 6193172 The information contained in this E-mail is intended only for the confidential use of the named recipient. If the reader of this message is not the intended recipient or the person responsible for delivering it to the recipient, you are hereby notified that you have received this communication in error and that any review, dissemination or copying of this communication is strictly prohibited. If you have received this in error, please notify the sender immediately by telephone at the number above and erase the message You are requested to carry out your own virus check before opening any attachment.
Re: Syn flood crashed my LAN
Martin, Depending on the type of box you have and amount of Ram on your box (throw Resources at the problem and hope that the resources > than the attack I would look at PF Limits and increase the maximum amount of states in the firewall it is 1 by default...which is on the low side(in my humble opinion) check man pf.conf for more details on limits There have been a number of improvements to syn flood handling made by henning so you can try -current if you want to see further improvements Regards, Tom Smyth On 12 February 2018 at 00:26, Martin Hansonwrote: > Hi, > > I have a home network that is segmented into 3 different zones using a NIC > with 4 ports sitting on an OpenBSD firewall/dhcp server. One port is > connected to the Internet (ISP router) and each of the three others has a > D-Link DGS-1005D switch connected to each. > > So.. > > LAN1 = 192.168.1.0 > LAN2 = 192.168.2.0 > LAN3 = 192.168.3.0 > > Learning more about networking I wanted to test a SYN flood so I set up a > couple of boxes on LAN1 and LAN3 to flood a box on LAN2. I used "hping3" with > the "S" and "flood" options. > > Running a regular ping in a terminal I could see how the response time > decreased and eventually the box began to loose packages. > > However after a while it seemed like the entire internal network went down. > > No box on any LAN could get an IP address from the DHCP server on the OpenBSD > box. > > I eventually rebooted the OpenBSD box, but that didn't immediately help, and > only after powering down the switches and powering the switches on again, > everything worked again. > > I have been looking through the PF documentation to see if PF somehow blocks > SYN flooding, but I am not using synproxy on any rules. > > What could cause such a "melt down" of the entire network because of a SYN > flood to a box? > > I suspect that the D-Link switches are pretty bad and maybe are the cause of > the problem? > > I eventually will try again to see if I can determine what's causing the > "melt down", but I want to know if anyone perhaps has experienced similar > results during some testing? > > Many thanks in advance. > > Kind regards, > > Martin > -- Kindest regards, Tom Smyth Mobile: +353 87 6193172 The information contained in this E-mail is intended only for the confidential use of the named recipient. If the reader of this message is not the intended recipient or the person responsible for delivering it to the recipient, you are hereby notified that you have received this communication in error and that any review, dissemination or copying of this communication is strictly prohibited. If you have received this in error, please notify the sender immediately by telephone at the number above and erase the message You are requested to carry out your own virus check before opening any attachment.
Re: Syn flood crashed my LAN
Try -current[0]. I think henning will be glad to hear how his new toy works in the field. martijn@ [0] https://marc.info/?l=openbsd-cvs=151796069324365=2 On 02/12/18 01:26, Martin Hanson wrote: > Hi, > > I have a home network that is segmented into 3 different zones using a NIC > with 4 ports sitting on an OpenBSD firewall/dhcp server. One port is > connected to the Internet (ISP router) and each of the three others has a > D-Link DGS-1005D switch connected to each. > > So.. > > LAN1 = 192.168.1.0 > LAN2 = 192.168.2.0 > LAN3 = 192.168.3.0 > > Learning more about networking I wanted to test a SYN flood so I set up a > couple of boxes on LAN1 and LAN3 to flood a box on LAN2. I used "hping3" with > the "S" and "flood" options. > > Running a regular ping in a terminal I could see how the response time > decreased and eventually the box began to loose packages. > > However after a while it seemed like the entire internal network went down. > > No box on any LAN could get an IP address from the DHCP server on the OpenBSD > box. > > I eventually rebooted the OpenBSD box, but that didn't immediately help, and > only after powering down the switches and powering the switches on again, > everything worked again. > > I have been looking through the PF documentation to see if PF somehow blocks > SYN flooding, but I am not using synproxy on any rules. > > What could cause such a "melt down" of the entire network because of a SYN > flood to a box? > > I suspect that the D-Link switches are pretty bad and maybe are the cause of > the problem? > > I eventually will try again to see if I can determine what's causing the > "melt down", but I want to know if anyone perhaps has experienced similar > results during some testing? > > Many thanks in advance. > > Kind regards, > > Martin >
Re: Syn flood crashed my LAN
On 12.02.18 01:26, Martin Hanson wrote: > Hi, > > I have a home network that is segmented into 3 different zones using a NIC > with 4 ports sitting on an OpenBSD firewall/dhcp server. One port is > connected to the Internet (ISP router) and each of the three others has a > D-Link DGS-1005D switch connected to each. > > So.. > > LAN1 = 192.168.1.0 > LAN2 = 192.168.2.0 > LAN3 = 192.168.3.0 > > Learning more about networking I wanted to test a SYN flood so I set up a > couple of boxes on LAN1 and LAN3 to flood a box on LAN2. I used "hping3" with > the "S" and "flood" options. > > Running a regular ping in a terminal I could see how the response time > decreased and eventually the box began to loose packages. > > However after a while it seemed like the entire internal network went down. > > No box on any LAN could get an IP address from the DHCP server on the OpenBSD > box. > > I eventually rebooted the OpenBSD box, but that didn't immediately help, and > only after powering down the switches and powering the switches on again, > everything worked again. > > I have been looking through the PF documentation to see if PF somehow blocks > SYN flooding, but I am not using synproxy on any rules. > > What could cause such a "melt down" of the entire network because of a SYN > flood to a box? > > I suspect that the D-Link switches are pretty bad and maybe are the cause of > the problem? > > I eventually will try again to see if I can determine what's causing the > "melt down", but I want to know if anyone perhaps has experienced similar > results during some testing? > > Many thanks in advance. > > Kind regards, > > Martin You run a denial of service attack against your home network. As a result your network denials service. Sounds like you have proven that syn flooding is an effective denial of service attack in your network. Yes, your switches cannot handle the amount of traffic you putting on them. No, your switches are not the problem. Your syn flooding of the network is causing the problem. Cheers, Bruno -- I really hope this whole thing works, I won't be able to test everything beforehand