Re: [9front] [PITCH] ip/null

[Jacob Moody <moody@posixcafe.org>]

On 12/11/23 13:17, hiro wrote:
> is your example more fine-grained than routing tables?
> in that case i misread the example.

My example was not, but ipmux allows you to index
arbitrarily in to the ip data portion to do matching.

> 
> On 12/11/23, Jacob Moody <moody@posixcafe.org> wrote:
>> Indeed, but right now ipmux is the only tool we have for doing any
>> filtering more fine grained then routing tables as far as I know.
>>
>> I would like our own pf-like but that would require going back to
>> the drawing board.
>>
>> On 12/11/23 13:05, hiro wrote:
>>> it would be good if it wouldn't need to get all the way to userland
>>> before being dropped.
>>>
>>> On 12/11/23, Jacob Moody <moody@posixcafe.org> wrote:
>>>> This as obsoleted by cinap's aux/dial(1).
>>>> It functionally works the same here except you would
>>>> need an explicit direction to /dev/null.
>>>>
>>>> ie.
>>>>
>>>> aux/dial
>>>> 'ipmux!ifc=my.external.ip;dst=192.168.0.0&255.255.0.0|10.0.0.0&255.0.0.0'
>>>>>
>>>> /dev/null
>>>>
>>>> On 12/11/23 12:54, unobe@cpan.org wrote:
>>>>> FWIW, I haven't seen anyone else comment on this, but I like it.
>>>>>
>>>>> Quoth Jacob Moody <moody@mail.posixcafe.org>:
>>>>>> As I play around more with 9front as my router, I found myself
>>>>>> reaching
>>>>>> for some
>>>>>> kind of 'firewall'. I find that we already have a pretty good
>>>>>> interface
>>>>>> in the kernel
>>>>>> in the form of ipmux. But there isn't too many ways of making use of
>>>>>> it
>>>>>> as is. I hacked up
>>>>>> something quick to just drop packets matching a filter on to the
>>>>>> floor.
>>>>>> If others find it
>>>>>> useful I can make up a man page and present again with a bit more
>>>>>> polish.
>>>>>>
>>>>>> Some examples:
>>>>>> # Drop inbound private range
>>>>>> ip/null
>>>>>> 'ifc=my.external.ip;dst=192.168.0.0&255.255.0.0|10.0.0.0&255.0.0.0'
>>>>>>
>>>>>> # google verboden
>>>>>> ip/null 'ifc=my.internal.ip;dst=8.8.8.8;src=192.168.0.0&255.255.0.0'
>>>>>>
>>>>>> thanks,
>>>>>> moody
>>>>>>
>>>>>> --- /dev/null
>>>>>> +++ b//sys/src/cmd/ip/null.c
>>>>>> @@ -1,0 +1,36 @@
>>>>>> +#include <u.h>
>>>>>> +#include <libc.h>
>>>>>> +
>>>>>> +void
>>>>>> +usage(void)
>>>>>> +{
>>>>>> +	fprint(2, "usage: %s filter\n", argv0);
>>>>>> +	exits("usage");
>>>>>> +}
>>>>>> +
>>>>>> +void
>>>>>> +main(int argc, char **argv)
>>>>>> +{
>>>>>> +	char buf[64 * 1024];
>>>>>> +	int fd;
>>>>>> +
>>>>>> +	ARGBEGIN{
>>>>>> +	default:
>>>>>> +		usage();
>>>>>> +		break;
>>>>>> +	}ARGEND
>>>>>> +	if(argc < 1)
>>>>>> +		usage();
>>>>>> +
>>>>>> +	fd = dial(smprint("ipmux!%s", argv[0]), nil, nil, nil);
>>>>>> +	if(fd < 0)
>>>>>> +		sysfatal("dial: %r");
>>>>>> +
>>>>>> +	for(;;)
>>>>>> +		switch(read(fd, buf, sizeof buf)){
>>>>>> +		case -1:
>>>>>> +			sysfatal("read: %r");
>>>>>> +		case 0:
>>>>>> +			return;
>>>>>> +		}
>>>>>> +}
>>>>>
>>>>
>>>>
>>
>>