My scapy (1.0.4-1) cannot be invoked from the command line without crashing :-
$ scapy -h
/usr/bin/scapy:3101: Warning: 'with' will become a reserved keyword in Python
2.6
/usr/bin/scapy:3103: Warning: 'with' will become a reserved keyword in Python
2.6
INFO: Can't import PyX. Won't be able to use psdump() or pdfdump()
Traceback (most recent call last):
File "/usr/bin/scapy", line 10647, in <module>
class Conf(ConfClass):
File "/usr/bin/scapy", line 10693, in Conf
route = Route()
File "/usr/bin/scapy", line 1911, in __init__
self.resync()
File "/usr/bin/scapy", line 1915, in resync
self.routes = read_routes()
File "/usr/bin/scapy", line 2234, in read_routes
ifreq = ioctl(s, SIOCGIFADDR,struct.pack("16s16x",iff))
IOError: [Errno 99] Cannot assign requested address
I have one interface up, and one interface unconfigured (no cable present at
boot time)
$ ifconfig
eth0 Link encap:Ethernet HWaddr <DELETED>
UP BROADCAST MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)
Interrupt:9 Base address:0x2c00
eth1 Link encap:Ethernet HWaddr <DELETED>
inet addr:<DELETED> Bcast:<DELETED> Mask:255.255.255.192
inet6 addr: <DELETED>/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:474 errors:0 dropped:0 overruns:0 frame:0
TX packets:233 errors:0 dropped:0 overruns:0 carrier:0
collisions:25 txqueuelen:1000
RX bytes:214769 (209.7 KiB) TX bytes:22745 (22.2 KiB)
Interrupt:11 Base address:0x8800
/proc/net/route doesn't seem to offer any differentiation between eth0
and eth1 ... I have no idea if this is correct/valid or not.
$ cat /proc/net/route
Iface Destination Gateway Flags RefCnt Use Metric Mask
MTU Window IRTT
eth1 <DELETED> 00000000 0001 0 0 0
C0FFFFFF 0 0 0
eth0 0000FEA9 00000000 0001 0 0 0
0000FFFF 0 0 0
eth1 0000FEA9 00000000 0001 0 0 1000
0000FFFF 0 0 0
eth1 00000000 <DELETED> 0003 0 0 0
00000000 0 0 0
eth0 00000000 00000000 0001 0 0 1000
00000000 0 0 0
(This seems to be the same as the output of netstat)
$ netstat -rn
Kernel IP routing table
Destination Gateway Genmask Flags MSS Window irtt Iface
<DELETED> 0.0.0.0 255.255.255.192 U 0 0 0 eth1
169.254.0.0 0.0.0.0 255.255.0.0 U 0 0 0 eth0
169.254.0.0 0.0.0.0 255.255.0.0 U 0 0 0 eth1
0.0.0.0 <DELETED> 0.0.0.0 UG 0 0 0 eth1
0.0.0.0 0.0.0.0 0.0.0.0 U 0 0 0 eth0
scapy tests each interface for the flag RTF_UP (around line 2232)
for l in f.readlines()[1:]:
iff,dst,gw,flags,x,x,x,msk,x,x,x = l.split()
if int(flags,16) & RTF_UP == 0:
continue
ifreq = ioctl(s, SIOCGIFADDR,struct.pack("16s16x",iff))
The ioctl call on that last line fails on my eth0. As mentioned above,
if I manually give eth0 an address, the ioctl call will work ...
$ sudo ifconfig eth0 10.10.10.10
$ scapy -h
/usr/bin/scapy:3101: Warning: 'with' will become a reserved keyword in Python
2.6
/usr/bin/scapy:3103: Warning: 'with' will become a reserved keyword in Python
2.6
INFO: Can't import PyX. Won't be able to use psdump() or pdfdump()
Usage: scapy.py [-s sessionfile]
So somehow we have to convince scapy to leave the unconfigured interface
alone.
It looks like the udev attribute {carrier} is the right thing to query
$ udevinfo -p /sys/class/net/eth0 -a|grep carrier
ATTR{carrier}=="0"
$ udevinfo -p /sys/class/net/eth1 -a|grep carrier
ATTR{carrier}=="1"
but how can scapy (upstream) know that it is in a udev environment?
I see from dmesg that there is a test for the link state of an interface :-
ADDRCONF(NETDEV_UP): eth0: link is not ready
This message comes via netdevice.h in the kernel, and that's getting
beyond me, sorry.
The workaround is to make sure that you don't have any unconfigured interfaces
when you want to run scapy.
I've logged this issue onto the scapy upstream ticketing,
http://trac.secdev.org/scapy/ticket/40
--
[feisty] scapy crashes using any version of python
https://bugs.launchpad.net/bugs/96753
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