netdev - Re: IP header identification field is zero, why?

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <4ACDAE64.5020101@gmail.com>
Date:	Thu, 08 Oct 2009 11:18:28 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	thomas yang <lampsu@...il.com>
CC:	netdev@...r.kernel.org
Subject: Re: IP header identification field is zero, why?

thomas yang a écrit :

> The IP ID for TCP is non-zero, but for UDP is zero,  strange.
> 
> I want to make the IP ID (not always zero) for UDP packets, what should I do?
> (I want to use 'IP header ID, flags, offset, protocol' to identify an
> IP packets)

As I said, you can connect() your udp socket, if you send/receive trafic to/from a given destination.

if (connected_sock)
	res = connect(sock, (struct sockaddr *)&addr, sizeof(addr));

(Only once)


Then, your sendto() can be faster (because no route lookup is performed)

   if (sendto(sock, buffer, psize, 0,
                  connected_socks ? NULL : (struct sockaddr *)&addr,
                                   sizeof(struct sockaddr_in)) != -1)

Then linux *will* generate an ID for each datagram.
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html