Change #208555

Comments

linux: fix check for mac80211 phydev.
If pcap_create() is passed an invalid interface name, have
pcap_can_set_rfmon() fail with PCAP_ERROR_NO_SUCH_DEVICE rather than
reporting "this doesn't support monitor mode", and have an attempt to
enter monitor mode in pcap_activate() return PCAP_ERROR_NO_SUCH_DEVICE
rather than PCAP_ERROR_RFMON_NOTSUP.

This fixes a bug wherein tcpdump, when pased an interface index as an
argument to -i, and also passed -I, would report that the device can't
support monitor mode, even if that index corresponds to a device that
*can* support monitor mode, rather than attempting to open the device
and put the device into monitor mode.  (Given that on some OSes an
interface can have a purely-numeric name, when given a numeric argument
to -i, it first tries to open it as a device and, if that gets a "no
such device" error, it tries to interpret it as a device index.  And,
given that Linux systems can have device names such as wlx0013eff12e78,
Windows isn't the only OS in which ugly long device names make device
indices convenient alternatives to device names.)

Changed files

• pcap-linux.c