Date: Wed, 26 Jun 2002 15:52:04 -0400 From: Anthony Volodkin <anthonyv@brainlink.com> To: Julian Elischer <julian@elischer.org> Cc: freebsd-net@freebsd.org Subject: Re: Forwarding UDP packets Message-ID: <3D1A1B64.402@brainlink.com> References: <Pine.BSF.4.21.0206261231580.64758-100000@InterJet.elischer.org>
next in thread | previous in thread | raw e-mail | index | archive | help
I use poptop+the pppd that is included with 4.6-RELEASE. On the XP
side, my friend just sets up a "Virtual Private Networking Connection"
using the native XP client.
Here are my /etc/ppp/options, if you wanted protocol info:
lock
debug
auth
proxyarp
+chap
+chapms
+chapms-v2
and the relevant portion of ppp.conf:
pptp:
enable chap
enable proxy
set ifaddr 192.168.1.100 192.168.2.200-192.168.2.205 255.255.255.0
>what method of doing pptp are you using?
>
>
>On Wed, 26 Jun 2002, Anthony Volodkin wrote:
>
>
>
>>Hi,
>>
>>Recently I've been faced with an odd problem. I setup a pptp link to my
>>network from my friend's XP machine. While the link functions fine
>>(both ends can ping each other, etc), there is one problem with it. I
>>cannot get any broadcast packets through the link. I receive them on
>>the tun0 interface, but no matter what I try i can't get them out of the
>>fxp0 interface. I cannot get them to go the other way either. I know
>>this is against standards, as they suggest routers should not forward
>>broadcast packets, but I would still like to have this ability.
>>
>>Did anyone ever write a patch of some sort or maybe found a tool that
>>does this type of thing?
>>(many people suggested natd, and after playing with that i was able to
>>redirect some bcast packets from tun0 to 1 host on my lan. I was not
>>able to do that in the other direction, however.)
>>
>>I've found an old post on the hackers list by Jonathan Chen that
>>included a patch to enable this kind of functionality. I applied it to
>>my 4.6-RELEASE kernel and it didn't do anything but add a sysctl
>>variable. Any help would be greatly appreciated.
>>
>>Here is that post:
>>
>>---------------------------------------------------
>>
>>On FreeBSD -CURRENT and -STABLE, packets to broadcast addresses are not
>>forwarded. For instance, if I have a FreeBSD router with interfaces
>>192.168.1.1 and 192.168.2.1, and I send packets from 192.168.1.2 to
>>192.168.2.255, the packets are dropped to the floor. IMO, this is wrong...
>>but I haven't consulted all the RFC's so I'm not sure if some standard out
>>there calls for it. In any case, the following patch creates a sysctl knob
>>to turn on or off this feature (since it can be considered a security risk
>>by some). I just want to ask around in case I turned out to be doing
>>something incredibly evil. Comments?
>>
>>-Jon
>>
>>Index: in.h
>>===================================================================
>>RCS file: /export/ncvs/src/sys/netinet/in.h,v
>>retrieving revision 1.55
>>diff -u -r1.55 in.h
>>--- in.h 2001/06/15 00:37:27 1.55
>>+++ in.h 2001/08/09 15:12:19
>>@@ -452,7 +452,8 @@
>> #define IPCTL_FASTFORWARDING 14 /* use fast IP forwarding code */
>> #define IPCTL_KEEPFAITH 15 /* FAITH IPv4->IPv6 translater ctl */
>> #define IPCTL_GIF_TTL 16 /* default TTL for gif encap packet */
>>-#define IPCTL_MAXID 17
>>+#define IPCTL_FORWARD_BROADCAST 18 /* forward broadcast packets */
>>+#define IPCTL_MAXID 18
>>
>> #define IPCTL_NAMES { \
>> { 0, 0 }, \
>>Index: ip_input.c
>>===================================================================
>>RCS file: /export/ncvs/src/sys/netinet/ip_input.c,v
>>retrieving revision 1.174
>>diff -u -r1.174 ip_input.c
>>--- ip_input.c 2001/06/23 17:17:58 1.174
>>+++ ip_input.c 2001/08/09 15:33:59
>>@@ -103,6 +103,10 @@
>> SYSCTL_INT(_net_inet_ip, IPCTL_FORWARDING, forwarding, CTLFLAG_RW,
>> &ipforwarding, 0, "Enable IP forwarding between interfaces");
>>
>>+int ipforward_broadcast = 0;
>>+SYSCTL_INT(_net_inet_ip, IPCTL_FORWARD_BROADCAST, forward_broadcast,
>>CTLFLAG_RW,
>>+ &ipforward_broadcast, 0, "Enable broadcast packets when forwarding
>>IP packets");
>>+
>> static int ipsendredirects = 1; /* XXX */
>> SYSCTL_INT(_net_inet_ip, IPCTL_SENDREDIRECTS, redirect, CTLFLAG_RW,
>> &ipsendredirects, 0, "Enable sending IP redirects");
>>@@ -1684,7 +1688,8 @@
>> }
>>
>> error = ip_output(m, (struct mbuf *)0, &ipforward_rt,
>>- IP_FORWARDING, 0);
>>+ IP_FORWARDING|
>>+ (ipforward_broadcast?IP_ALLOWBROADCAST:0), 0);
>> if (error)
>> ipstat.ips_cantforward++;
>> else {
>>
>>
>>--
>>Anthony Volodkin
>>
>>
>>To Unsubscribe: send mail to majordomo@FreeBSD.org
>>with "unsubscribe freebsd-net" in the body of the message
>>
>>
>>
>
>
>
To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-net" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?3D1A1B64.402>