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Intermittant "WARNING: Mac address to reach destination not found. Using broadcast." on windows 10.
Brief description
When using Automaton.send() or even getmacbyip(), it intermittently fails to acquire the mac address for the default gateway despite it being visible in the windows ARP table using arp -a.
Scapy version
2.4.5rc1.dev162
Python version
3.9.0 (tags/v3.9.0:9cf6752, Oct 5 2020, 15:34:40) [MSC v.1927 64 bit (AMD64)]
Operating system
Windows 10
Additional environment information
10.0.0.10 -> SW -> 10.0.0.250 -> PublicIP -> 1.1.1.1
See a Gist here of what I am running and a good vs bad output. https://gist.github.com/0xKate/c5757a92f8a937142b78630621c8be7d
How to reproduce
On average 1/10 times getmacbyip() will return None. On average 1/10 times Automaton.send() will "WARNING: Mac address to reach destination not found"
route = conf.route.route("0.0.0.0")
gw_hwaddr = getmacbyip(route[2])
print(gw_hwaddr)
Actual result
Scapy Version: 2.4.5rc1.dev162 Python Version: 3.9.0 (tags/v3.9.0:9cf6752, Oct 5 2020, 15:34:40) [MSC v.1927 64 bit (AMD64)]
[18:40:33:951611] Local
Iface: \Device\NPF_{_-5E428F13573A}
IP: 10.0.0.10
MAC: 4c:_:_:_:_:78
---------- Scapy conf.route ----------
Network Netmask Gateway Iface Output IP Metric
0.0.0.0 0.0.0.0 10.0.0.250 Killer E2500 Gigabit Ethernet Controller 10.0.0.10 25
10.0.0.0 255.255.255.0 0.0.0.0 Killer E2500 Gigabit Ethernet Controller 10.0.0.10 281
10.0.0.10 255.255.255.255 0.0.0.0 Killer E2500 Gigabit Ethernet Controller 10.0.0.10 281
10.0.0.255 255.255.255.255 0.0.0.0 Killer E2500 Gigabit Ethernet Controller 10.0.0.10 281
224.0.0.0 240.0.0.0 0.0.0.0 Killer E2500 Gigabit Ethernet Controller 10.0.0.10 281
255.255.255.255 255.255.255.255 0.0.0.0 Killer E2500 Gigabit Ethernet Controller 10.0.0.10 281
---------- Windows arp -a ----------
['10.0.0.250', '00:_:_:_:_:19', 'dynamic']
['10.0.0.255', 'ff:ff:ff:ff:ff:ff', 'static']
[18:44:20:458746] Getting Mac by ip...
[18:44:22:460377] Scapy getmacbyip: None
[18:44:22:460377] Scapy's getmacbyip() Failed to get arp entry for 10.0.0.250.
10.0.0.250 exists inside windows arp table, hwaddr of: 00:_:_:_:_:19
[18:44:22:524113] BEGIN
WARNING: Mac address to reach destination not found. Using broadcast.
[18:44:24:533194] 10.0.0.10 > 1.1.1.1 icmp
[18:44:27:533442] TIMEOUT
[18:44:27:533442] RETRYING 10.0.0.10 > 1.1.1.1 icmp
[18:44:27:559796] ICMP 1.1.1.1 > 10.0.0.10 echo-reply 0
[18:44:28:561234] 10.0.0.10 > 1.1.1.1 icmp
[18:44:28:583723] ICMP 1.1.1.1 > 10.0.0.10 echo-reply 0
[18:44:29:586249] 10.0.0.10 > 1.1.1.1 icmp
[18:44:29:611411] ICMP 1.1.1.1 > 10.0.0.10 echo-reply 0
[18:44:30:613542] 10.0.0.10 > 1.1.1.1 icmp
[18:44:30:636495] ICMP 1.1.1.1 > 10.0.0.10 echo-reply 0
[18:44:30:636495] END
Process finished with exit code 0
Expected result
[18:46:04:866248] Getting Mac by ip...
[18:46:04:870180] Scapy getmacbyip: 00:_:_:_:_:19
[18:46:04:870180] BEGIN
[18:46:04:873591] 10.0.0.10 > 1.1.1.1 icmp
[18:46:04:897557] ICMP 1.1.1.1 > 10.0.0.10 echo-reply 0
[18:46:05:899327] 10.0.0.10 > 1.1.1.1 icmp
[18:46:05:923340] ICMP 1.1.1.1 > 10.0.0.10 echo-reply 0
[18:46:06:925417] 10.0.0.10 > 1.1.1.1 icmp
[18:46:06:959108] ICMP 1.1.1.1 > 10.0.0.10 echo-reply 0
[18:46:07:961328] 10.0.0.10 > 1.1.1.1 icmp
[18:46:07:983304] ICMP 1.1.1.1 > 10.0.0.10 echo-reply 0
[18:46:07:983304] END
Process finished with exit code 0
Related resources
It may be worth noting that Scapy is generating an unnecessary ARP request since the entry is already accessible in the windows ARP table.
The other thing I notice is getmacbyip() tends to timeout after 2 seconds despite the ARP request it generated being answered within 0.000177 seconds.
For main issue: I had the same issue, when I'm connected over cable to my router using switch in the meantime, even as sudo on linux to my own router :) For additional thing about unnecessary ARP request - Scapy have it's own route tables etc, so that's the reason for that :) About timeout after 2s, even if answer is there - It's evidently a bug.
Okay that makes sense. Thanks. I'm deploying to raspbery pi linux for now and its working great.
i got no freaking idea what the heck you guys said the only thing i know is that i have the problem: "Mac address to reach destination not found. Using broadcast." and i have no freaking idea how to fix it
Scapy mainly is developed targeting Linux it's awesome that it works on windows at all.
Even python asyicio runs different on windows then on Linux. It's just not the main platform scapy is developed for.
If I had to guess: It's probably some kind of race condition with one of the libraries exclusively on Windows because it only happens to me when arp requests are answered incredibly fast.
I closed the issue because most of the scapy docs suggested to use Linux if it's not working right on windows. I did that and have not had an issue and since.