Dear Borja, Thank you for your offer, but I already found out what I wanted for fixed source IP address and several seconds delays (that firewalls are ok with it). For "real" research much more would need to be done, but I don't have enough time and resources for it now. Just in case someone is interested in conducting this kind of research, IMO it would be interesting to open delay host to all internet and point ATLAS probes to it, then vary delay time and try to find out delays at which firewalls start to close connections prematurely. Then repeat it for TCP and (especially interesting) UDP, but AFAIU current probes can only send TCP/UDP test packets to anchors, therefore it would require coordination with ATLAS people. (I did not study literature, so maybe it has already been done recently.) -- With Best Regards, Marat Khalili On 29/05/17 09:47, Borja Marcos wrote:
On 26 May 2017, at 14:17, Marat Khalili <mkh@rqc.ru> wrote:
Annika, Borja, thank you for the suggestions. I'll consider purpose-building such host, but still hope to stumble upon existing one (some remote observatory on a satellite link probably…) An example creating a 20 second delay.
# ipfw pipe 10 config delay 9999
Now we create a couple of firewall rules. I will give this “royal treatment” to betweeen “pinger” and “pingee”
# ipfw add 121 pipe 10 icmp from x.y.z.t to me # ipfw add 122 pipe 10 icmp from me to x.y.z.t
(Adding delay to both the ping and the ping ack so that the maximum delay I can get is 20000 ms)
And testing:
64 bytes from a.b.c.d: icmp_seq=259 ttl=60 time=20000.069 ms
If you need it, give me the IP addresses from which you intend to do the tests and the delay you need and I can create a ping target on my test server in Amazon’s EC2.
Cheers,
Borja.