In modern desktops, the 10gbps network hardware DMAs the packet directly into the CPU's cache - actually bypassing memory. This is between 10 and 100 times faster than you can get through the OpenBSD kernel, even if you simply configured it to simply bridge two adapters with no inspection. I'm assuming 10 million concurrent TCP connections here, with 100,000 rules. In todays terms, it means it's relatively trivial to use a desktop system (quad-core, 3 GHz) to create a 10-gbps firewall that passes 30 million packets/second (bidirectional), at wire speed. I've been writing such apps for over 20 years, and have constantly struggled against disbelief as people simply cannot believe that machines can run this fast. It means networking can operating 10 times to even a 100 times faster than trying to move packets through the kernel. You have no comprehension of how fast this can be.
#Userspace netmap drivers#
These user-space ring-mode network drivers operate with essentially zero overhead. There needs to be a system whereby apps can request exclusive access to hardware resources, such as GPUs, FPGAs, hardware crypto accelerators, and of course, network adapters. Since single-purpose, single-application computers are the norm, "general purpose" operating systems need to be written to include that concept. While such machines do exist, most computers today are dedicated to a single purpose, such as supercomputer computations, or a domain controller, or memcached, or a firewall. Today's computers are no longer multi-purpose, multi-user machines. That today's operating-systems don't offer user-mode stacks is a flaw. User-mode isolation is a security feature. No matter how bad a user-mode TCP/IP stack is written, any vulnerabilities affect just that process, and not the integrity of the system. I've crashed the network stack on mainframes - the crash only affects the networking process and not the kernel or other apps. These things already put the networking stack in user space, for security reasons. Take "microkernels" like Hurd or IBM mainframes. That means it's going to repeat all the same mistakes of the past, such as "ping of death" when a packet reassembles to more then 65536 bytes. In addition, it ultimately means that the application is going to have to implement it's own TCP/IP stack. This violates many principles of a "general purpose operating system". The problem with things like netmap is that it means the network hardware no longer is a shareable resource, but instead must be reserved for a single application. There are projects similar to this known as "PF_RING" and "Intel DPDK". Netmap currently works on FreeBSD and Linux. What that means is the hardware delivers network packets directly to an application, bypassing the operating system's network stack.
"Netmap" is a user-space network ring-buffer. In practice, virtually nobody uses it, because it makes too many sacrifices in the name of security.
In theory, it's for those who care a lot about security. A lot of security-related projects get their start on OpenBSD. One variant of BSD focuses on security, called " OpenBSD". In our simple example we are going toĬreate a new Generic Netlink family named “DOC_EXMPL”.Even by OpenBSD standards, this rejection of 'netmap' is silly and clueless.īSD is a Linux-like operating system that powers a lot of the Internet, from Netflix servers to your iPhone. The first step is to define the family itself, which we do by creating an In order to help demonstrate these steps below is a simple example broken down Registering a Generic Netlink family is a simple four step process: define theįamily, define the operations, register the family, register the operations.
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