Nmap Development mailing list archives
Re: libpcap bug workaround for localhost? (Re: pcap_dispatch() returns outgoing packet despite pcap_setfilter)
From: Fyodor <fyodor () insecure org>
Date: Sat, 29 Jan 2005 21:54:48 -0800
On Fri, Jan 14, 2005 at 04:05:56PM +0100, Martin Ma?ok wrote:
void set_pcap_filter(... [..] if (o.debugging) log_write(LOG_STDOUT, "Packet capture filter (device %s): %s\n", target->device, buf); /* Due to apparent bug in libpcap */ if (islocalhost(target->v4hostip())) buf[0] = '\0'; [..] OK, so, at least, the order of those commands should be reversed. Second, what is (was?) the bug? It seems to work good on my localhost, is this workaround still needed?
OK, I've reversed the order for the next version so that the debug message is correct. I don't remember the exact bugs I was seeing when placing a filter on localhost, but I do recall that it was a pain to track down :). So I'm not ready to remove that workaround yet. Nmap generally assumes that it may get superfluous packets back anyway and so it checks them again itself. So the libpcap filters are simply for efficiency -- allowing some of that filtering to be done earlier. Cheers, Fyodor --------------------------------------------------------------------- For help using this (nmap-dev) mailing list, send a blank email to nmap-dev-help () insecure org . List archive: http://seclists.org
Current thread:
- pcap_dispatch() returns outgoing packet despite pcap_setfilter Martin Mačok (Jan 09)
- libpcap bug workaround for localhost? (Re: pcap_dispatch() returns outgoing packet despite pcap_setfilter) Martin Mačok (Jan 14)
- Re: libpcap bug workaround for localhost? (Re: pcap_dispatch() returns outgoing packet despite pcap_setfilter) Fyodor (Jan 29)