Re: Two NSE questions

[Fyodor <fyodor () insecure org>]

On Sat, Aug 29, 2009 at 08:46:39PM -0500, Ron wrote:
> First, I need to set my source port to UDP/68 for these transactions. I 
> don't see any way to do that using the connect() function. I realize 
> that UDP/68 is reserved so r00t is required, but -sU requires root anyways.

This is supported by Nsock, but there may not currently be an NSE
binding for using this feature.  Ncat supports this (try ncat -u -p 68
scanme.nmap.org).  In Nsock, I think you basically just call this
function:

/* Sets the local address to bind to before connect() */
int nsi_set_localaddr(nsock_iod nsi, struct sockaddr_storage *ss, size_t sslen);

The local address and/or port number can be specified in the
sockaddr_storage.  Here is how ncat does it:

    if (srcport != -1) {
        if (o.listen)
            bye("-l and -p are incompatible.  Specify the address and port to bind to like you would a host to connect 
to.");

        if (srcaddr.storage.ss_family == AF_UNSPEC)
            srcaddr.storage.ss_family = o.af;
        if (o.af == AF_INET) {
            srcaddr.in.sin_port = htons((unsigned short) srcport);
            if (!srcaddrlen)
                srcaddrlen = sizeof(srcaddr.in);
        }
#ifdef HAVE_IPV6
        else {
            srcaddr.in6.sin6_port = htons((unsigned short) srcport);
            if (!srcaddrlen)
                srcaddrlen = sizeof(srcaddr.in6);
        }
#endif
    }

Cheers,
-F

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