Invalid argument error on Linux for `lo` interface

[fujiapple852]

Running:

trip www.bitwizard.nl -p udp -I lo -m stream

On Linux results in error:

Invalid argument (os error 22)

Note that lo is the loopback interface:

$ ip link show
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 9001 qdisc fq_codel state UP mode DEFAULT group default qlen 1000
    link/ether 02:42:54:20:f1:44 brd ff:ff:ff:ff:ff:ff
3: docker0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN mode DEFAULT group default
    link/ether 02:42:cc:3c:6a:10 brd ff:ff:ff:ff:ff:ff

[fujiapple852]

Perhaps we should filter out loopback from the list of interfaces?