From owner-freebsd-hackers Mon Jun 24 09:14:47 1996 Return-Path: owner-hackers Received: (from root@localhost) by freefall.freebsd.org (8.7.5/8.7.3) id JAA02817 for hackers-outgoing; Mon, 24 Jun 1996 09:14:47 -0700 (PDT) Received: from watermarkgroup.com (lor.watermarkgroup.com [38.246.139.30]) by freefall.freebsd.org (8.7.5/8.7.3) with SMTP id JAA02809 for ; Mon, 24 Jun 1996 09:14:42 -0700 (PDT) Received: from Kim.watermarkgroup.com by watermarkgroup.com (4.1/SMI-4.1) id AA07563; Mon, 24 Jun 96 12:14:09 EDT Message-Id: <31CEBECE.2D13@watermarkgroup.com> Date: Mon, 24 Jun 1996 12:14:07 -0400 From: Luoqi Chen Organization: The Watermark Group X-Mailer: Mozilla 3.0b3Gold (Macintosh; I; PPC) Mime-Version: 1.0 To: hackers@freebsd.org Subject: UDP still uses old address after pppd reconnects Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-hackers@freebsd.org X-Loop: FreeBSD.org Precedence: bulk This morning I reconnected to my ISP at a different IP address using pppd. And now at office I couldn't connect to one of my own udp server. Initially, I thought my ISP screwed up. But after a little more research, I believe this might be a bug with FreeBSD. Last night my IP address was ppp-2.ts-1.ptn.idt.net, this morning I connected at ppp-4.ts-1.ptn.idt.net. I wrote a little program sending UDP packet to its UDP echo port from office and watched the traffic through tcpdump, here is what I got, % tcpdump -l -i ppp0 port echo tcpdump: listening on ppp0 11:30:30.607374 lor.watermarkgroup.com.1751 > ppp-4.ts-1.ptn.idt.net.echo: udp 8 11:30:30.607674 ppp-2.ts-1.ptn.idt.net.echo > lor.watermarkgroup.com.1751: udp 8 This is only a problem for udp. I have no problem with tcp, tcp echo correctly sends back using ppp-4 address, and I can telnet to it just fine. By the way, I restarted inetd, it didn't help. I checked ifconfig, it showed correct address, % ifconfig ppp0 ppp0: flags=8051 mtu 1500 inet 169.132.64.4 --> 169.132.64.253 netmask 0xffffff00 One reason that might cause this behavior is that I setup an ipip tunnel between my machine at home and office. (Well, my ISP idt.net is not responding to my complaint that I can't connect to ftp.freebsd.org since I signed up. And I have to live with it before I find another cheap alternative. On the other hand, my company has a more decent connection through PSI net. This in fact has worked pretty well, until now). On my home PC, I setup a process listening to the /dev/tun. It wraps up all ip packets in udp and sends over to a sun at my office, where the packets are relay to the internet gateway throught /dev/nit. Incoming packets are picked up by the sun using arp proxy and sent back to my pc at home. This was done last Friday. I had not seen this problem prior to that. I restarted the tunnel process after I reestablished my ppp conntection, but it was not working now because of this udp problem. Anyone have any idea? -lq