[question] Scapy and Linux policy routing

[rafajot]

I have a linux host with routing policy rules that determine the gateway depending on source IP. If I set the source IP in scapy, for example

ans, unas = sr(IP(dst="180.87.124.196", src='192.xxx.xxx.xxx', ttl=1)/ICMP()/"Rozowe misie zjadaja ptysie",timeout=0.8, iface='eth3:174')

the policy routing does not work. The packet is always sent to default GW. Some time ago I saw here #762 the question about issue with scapy and iptables. So the answer was "Scapy sends packet at a low level and they are not seen by netfilter. ". I guess in this specific case the answer is going to be similar, scapy cooks packet on a different kernel layer and that's why policy based routing does not work. Is that correct?

BTW: I'm just wondering if it can have something to do with: #614

[guedou]

Scapy has its own routing table. On Linux, its content is only based on /proc/net/route that only reflect the default routing table.

You can submit a PR that implements reading routes from another source =)

[rafajot]

oh, thanks for this cool suggestion ;-). Is there any chance that this feature will land somewhere on to do list at least into sort of category "lets implement it when we stop willing to see our wives and kids till late night"?

[p-l-]

@rafajot if that's useful and well coded, it will land!

[guedou]

It is now referenced in #399 =)

[schlomo]

FYI, on Linux the pyroute2 library works with policy routing as described in https://stackoverflow.com/a/28570512

But, that doesn't work on other OS which is why I came to scapy in the first place.