Dummynet and fragments

Alvaro Saurin saurin at dcs.gla.ac.uk
Mon Dec 5 07:50:32 PST 2005


On 5 Dec 2005, at 14:41, Spadge wrote:

> Alvaro Saurin wrote:
>
>> The problem comes here: if I 'ping'  between these two machines,   
>> everything is fine, but if I 'ping' with a packet size of, ie,  
>> 2000,  no packets arrive at the receiver. Does it have to do with  
>> fragmented  packets? Do I have to include any other rule for  
>> dealing with fragments?
>
> 65100      0        0 deny log logamount 5000 ip from any to any frag
>
> Does this not effectively kill all frags? Are your unreceived  
> packets showing up in the log? And if not, are you sure that it's  
> BSD4 that's losing them, and not ubuntu3?
>
> Here's how my firewall handles frags:
>
> # Allow IP fragments to pass through
> /sbin/ipfw add pass all from any to any frag
>
> You may also want to set up something similar to handle ICMP.
>
> I've not used dummynet pipes in ages, I wonder if setting a larger  
> queue would help with my disconnect problems, or whether I really  
> do just need to give up and reinstall the entire OS.

Thank you, you're right, but adding something like 'pass all from any  
to any frag' does not put the IICMP packets through the dummynet  
pipe. I am not specially interested in 'ping's, but it happens the  
same for UDP traffic...

The problem is that, if I put ICMP/UDP/etc traffic through a pipe, it  
doesn't work when packets are fragmented. And letting fragments out  
of the pipe does not improve things...

Any idea? Thanks.

Alvaro

-- 
Alvaro Saurin <alvaro.saurin at gmail.com> <saurin at dcs.gla.ac.uk>





More information about the freebsd-net mailing list