Date: Sat, 19 Aug 2000 02:25:26 -0700 (PDT) From: markm68k@yahoo.com To: freebsd-gnats-submit@FreeBSD.org Subject: misc/20712: errant traceroute output from behind natd Message-ID: <20000819092526.0749637B43F@hub.freebsd.org>
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>Number: 20712 >Category: misc >Synopsis: errant traceroute output from behind natd >Confidential: no >Severity: serious >Priority: high >Responsible: freebsd-bugs >State: open >Quarter: >Keywords: >Date-Required: >Class: sw-bug >Submitter-Id: current-users >Arrival-Date: Sat Aug 19 02:30:02 PDT 2000 >Closed-Date: >Last-Modified: >Originator: Mark Miller >Release: 4.1-RELEASE >Organization: >Environment: FreeBSD myhost 4.1-RELEASE FreeBSD 4.1-RELEASE #7: Mon Aug 14 21:32:29 PDT 2000 me@myhost:/usr/src/sys/compile/MYHOST i386 >Description: When running traceroute from a computer which is connected to a FreeBSD 4.1-RELEASE box via a natd alias internal interface, the output report is not correct. This is the output of traceroute to www.freebsd.org: traceroute to freefall.freebsd.org (216.136.204.21), 30 hops max, 40 byte packets 1 freefall.freebsd.org (216.136.204.21) 4.164 ms 3.092 ms 3.053 ms 2 freefall.freebsd.org (216.136.204.21) 34 ms 31.441 ms 33.467 ms 3 freefall.freebsd.org (216.136.204.21) 27.402 ms 19.899 ms 19.829 ms 4 freefall.freebsd.org (216.136.204.21) 19.527 ms 37.497 ms 21.049 ms 5 freefall.freebsd.org (216.136.204.21) 20.22 ms 33.82 ms 30.611 ms 6 freefall.freebsd.org (216.136.204.21) 21.973 ms 21.07 ms 32.729 ms 7 freefall.freebsd.org (216.136.204.21) 38.95 ms 22.33 ms 21.103 ms 8 freefall.freebsd.org (216.136.204.21) 23.571 ms 21.945 ms 22.781 ms 9 freefall.freebsd.org (216.136.204.21) 33.078 ms 32.007 ms 35.327 ms 10 freefall.freebsd.org (216.136.204.21) 48.748 ms 32.419 ms 33.242 ms 11 freefall.freebsd.org (216.136.204.21) 32.552 ms 31.183 ms 33.039 ms 12 freefall.freebsd.org (216.136.204.21) 33.113 ms 36.89 ms 35.685 ms 13 freefall.freebsd.org (216.136.204.21) 31.588 ms 35.64 ms 37.114 ms 14 freefall.freebsd.org (216.136.204.21) 34.84 ms 46.235 ms 42.252 ms Some testing has resulted in the following conclusions: 1. Problems are very likely related to the natd code. 2. It appears to be limited to udp traffic. 3. It corrupts any icmp packets sent in response to a udp packet by changing the source of the icmp to be the destination of the udp packet. >How-To-Repeat: 1. install FreeBSD 4.1-RELEASE 2. configure an "open" firewall 3. configure natd with a single NIC, and an alias internal interface. 4. run "traceroute www.freebsd.org" from a different computer connected via natd to the freebsd box. 5. watch the errant output from traceroute. >Fix: unknown. >Release-Note: >Audit-Trail: >Unformatted: To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-bugs" in the body of the message
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