--- Begin Message ---On Nov 4, 2020, at 9:18 PM, Vaughan Wickham <v...@zen.net.au> wrote: > Version: libpcap version 1.5.3That's an older version (CentOS, proudly trailing-edge!), and only returns interfaces that the program can open. Capturing on Linux generally requires, at minimum, the CAP_NET_RAW privilege, and finding devices might also require CAP_NET_ADMIN; root privilege will also work. As such, you program will, by default, not be able to open *any* capture device, so: 1) if you were using a sufficiently more recent of libpcap, which return interfaces that the program doesn't have sufficient privileges to open (so that the user gets a "permission denied" error when trying to capture, which is somewhat clear about the underlying problem, rather than just not seeing any devices), you'd get "eth0" but then you'd get an error trying to open it (presumably that's why you're calling pcap_lookupdev()); 2) you need to give your program sufficient privileges. So try doing sudo setcap cap_net_raw,cap_net_admin+eip {your program} and then running the program. ("cap_net_admin" might not be necessary with 1.5.1.)
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