Re: "dnet: Failed to open device" errors on AIX, as root

[David Fifield <david () bamsoftware com>]

On Wed, Nov 21, 2012 at 09:19:37PM -0500, Ben Lentz wrote:
> > This is difficult to diagnose because we can't reproduce it. The reason
> > it fails only for on-link targets is because it's trying to do ARP scan,
> > which requires sending via an Ethernet handle, which is the part that's
> > failing. As a workaround, you can try the --send-ip option.
> >
> > Here are some other things you can try:
> >
> > Do you have /dev/bpf* devices?
> >
> > Try running "sudo truss nmap --route-dst 10.0.17.1" and sending us the
> > truss log. This will show if there is a system call that is failing and
> > causing the error.
>
> Thanks for your reply, David!
>
> - Using --send-ip looks like it's able to work around this
> problem... I am able to complete scans on the system using --send-ip
> against the local 10.0.17.0/24 network.
> - My AIX 6.1 TL7 SP5 does appear to have /dev/bpf[0-3], as character
> devices, owned by root.system (0:0), with permission mode 0400.
> - I will attach the gzipped truss output from the following two commands:

Thanks for this output. I think I see what the bug is; in short, it
looks like a known bug in AIX.

"BIND TO AF_NDD ADDRESS INCORRECTLY FAILS WITH EEXISTS"
http://www-01.ibm.com/support/docview.wss?uid=isg1IZ76058
http://www-01.ibm.com/support/docview.wss?uid=isg1IZ67350

The important part of the truss output is

10485844: 95158519: socket(23, 2, 1)                    = 3
10485844: 95158519: bind(3, 0x2FF2024C, 36)             Err#17 EEXIST
10485844: 95158519: close(3)                            = 0

which corresponds to this code in in libdnet-stripped/src/eth-ndd.c:

        if ((e->fd = socket(AF_NDD, SOCK_DGRAM, NDD_PROT_ETHER)) < 0)
                return (eth_close(e));
        sa.sndd_8022_family = AF_NDD;
        sa.sndd_8022_len = sizeof(sa);
        sa.sndd_8022_filtertype = NS_ETHERTYPE;
        sa.sndd_8022_ethertype = ETH_TYPE_IP;
        sa.sndd_8022_filterlen = sizeof(struct ns_8022);
        strlcpy(sa.sndd_8022_nddname, device, sizeof(sa.sndd_8022_nddname));
        if (bind(e->fd, (struct sockaddr *)&sa, sizeof(sa)) < 0)
                return (eth_close(e));

It looks like there is an update for the problem that you may be able to
install. Short of that, I don't think there's anything we can do, so I
hope the --send-ip workaround is good enough.

David Fifield
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