net-pf Modules

How many times have we all seen an error message like modprobe: can't locate module net-pf-5 at boot time, and wondered what it meant? I used to get this all the time when I chose to leave Appletalk support out of my kernel. Something (in my Red Hat system, at least) tried to access it anyway, and kerneld (or kmod these days) tried to load the corresponding module.

It's easy enough just to make these errors go away, by putting a line like alias net-pf-5 off into /etc/conf.modules. But what if it was something important? How do I know that net-pf-5 corresponds to something as useless (to me) as Appletalk? Fortunately, David Yaffe found a handy list of these numbers hiding in the kernel sources, in /usr/src/linux/include/linux/socket.h. For those of you who don't feel like digging around in there, here it is, in a friendlier format. The comments are taken verbatim from the source.

Module Alias Description Comment
net-pf-1 UNIX Unix domain sockets
net-pf-2 INET Internet IP Protocol
net-pf-3 AX25 Amateur Radio AX.25
net-pf-4 IPX Novell IPX
net-pf-5 APPLETALK AppleTalk DDP
net-pf-6 NETROM Amateur Radio NET/ROM
net-pf-7 BRIDGE Multiprotocol Bridge
net-pf-8 ATMPVC ATM PVCs
net-pf-9 X25 Reserved for X.25 project
net-pf-10 INET6 IP version 6
net-pf-11 ROSE Amateur Radio X.25 PLP
net-pf-12 DECnet Reserved for DECnet project
net-pf-13 NETBEUI Reserved for 802.2LLC project
net-pf-14 SECURITY Security callback pseudo AF
net-pf-15 KEY PF_KEY key management API
net-pf-16 NETLINK  
net-pf-17 PACKET Packet family
net-pf-18 ASH Ash
net-pf-19 ECONET Acorn Econet
net-pf-20 ATMSVC ATM SVCs
net-pf-22 SNA Linux SNA Project (nutters!)
net-pf-23 IRDA IRDA sockets