Date: Fri, 22 Feb 2013 19:19:02 GMT From: Alex Gingerich <alexg@g4.net> To: freebsd-gnats-submit@FreeBSD.org Subject: ports/176358: /net/freebsd-tftp Incorrect TFTP Behavior with Secondary IP Address Message-ID: <201302221919.r1MJJ21o069713@red.freebsd.org> Resent-Message-ID: <201302221920.r1MJK0Ih084637@freefall.freebsd.org>
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>Number: 176358
>Category: ports
>Synopsis: /net/freebsd-tftp Incorrect TFTP Behavior with Secondary IP Address
>Confidential: no
>Severity: non-critical
>Priority: low
>Responsible: freebsd-ports-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Fri Feb 22 19:20:00 UTC 2013
>Closed-Date:
>Last-Modified:
>Originator: Alex Gingerich
>Release: FreeBSD 9.0-RELEASE
>Organization:
G4 Communications
>Environment:
FreeBSD ns1.fibercast.net 9.0-RELEASE FreeBSD 9.0-RELEASE #0: Tue Jan 3 07:15:25 UTC 2012 root@obrian.cse.buffalo.edu:/usr/obj/usr/src/sys/GENERIC i386
>Description:
Initially, I noticed a quirk when using the default TFTP server. This is on a machine that has two IP addresses. They are configured as follows:
ifconfig_rl0=" inet 192.168.20.19 netmask 255.255.255.240"
ifconfig_rl0_alias0="192.168.20.18 netmask 255.255.255.240"
The first quirk I noticed, was that when a TFTP request comes in to 192.168.20.18, the tftp server sends the response out 192.168.20.19. This causes an inability to fetch from TFTP via the 192.168.20.18 address in NAT environments.
That in itself seems to be a bit of a problem... However, the behavior gets a little stranger when specifying RFC2348 blocksizes.
When I specify a blocksize of 1448, and request a file from 192.168.20.18, the TFTP server responds from 192.168.20.19, and immediatly starts sending the file in the first response packet.
However, when I specify a blocksize of 1448, but request from 192.168.20.19, the tftp server sends back an OACK in the first packet, waits for an acknowledgement from the client, and then begins sending a file.
>How-To-Repeat:
1) Set up a machine with two IP addresses, in the same subnet, on the same interfaces, and TFTP configured.
2) Get a TFTP file from both the primary and alias IP, both with and without the blocksize option.
3) Compare the resulting packet captures.
>Fix:
Patch attached with submission follows:
No. Time Source Destination Protocol Info
268 222.919651 10.100.1.34 192.168.20.18 TFTP Read Request, File: 7by2.cfg\000, Transfer type: octet\000, blksize\000=1448\000
Frame 268: 72 bytes on wire (576 bits), 72 bytes captured (576 bits)
Ethernet II, Src: Cabletro_0c:92:1a (00:e0:63:0c:92:1a), Dst: RealtekS_bb:a3:a1 (00:e0:4c:bb:a3:a1)
Internet Protocol, Src: 10.100.1.34 (10.100.1.34), Dst: 192.168.20.18 (192.168.20.18)
User Datagram Protocol, Src Port: 57202 (57202), Dst Port: tftp (69)
Trivial File Transfer Protocol
No. Time Source Destination Protocol Info
269 222.942042 192.168.20.19 10.100.1.34 UDP Source port: 58753 Destination port: 57202
Frame 269: 60 bytes on wire (480 bits), 60 bytes captured (480 bits)
Ethernet II, Src: RealtekS_bb:a3:a1 (00:e0:4c:bb:a3:a1), Dst: Cabletro_0c:92:1a (00:e0:63:0c:92:1a)
Internet Protocol, Src: 192.168.20.19 (192.168.20.19), Dst: 10.100.1.34 (10.100.1.34)
User Datagram Protocol, Src Port: 58753 (58753), Dst Port: 57202 (57202)
Data (15 bytes)
0000 00 06 62 6c 6b 73 69 7a 65 00 31 34 34 38 00 ..blksize.1448.
No. Time Source Destination Protocol Info
270 222.948184 10.100.1.34 192.168.20.19 UDP Source port: 57202 Destination port: 58753
Frame 270: 60 bytes on wire (480 bits), 60 bytes captured (480 bits)
Ethernet II, Src: Cabletro_0c:92:1a (00:e0:63:0c:92:1a), Dst: RealtekS_bb:a3:a1 (00:e0:4c:bb:a3:a1)
Internet Protocol, Src: 10.100.1.34 (10.100.1.34), Dst: 192.168.20.19 (192.168.20.19)
User Datagram Protocol, Src Port: 57202 (57202), Dst Port: 58753 (58753)
Data (4 bytes)
0000 00 04 00 00 ....
No. Time Source Destination Protocol Info
271 222.965259 192.168.20.19 10.100.1.34 UDP Source port: 58753 Destination port: 57202
Frame 271: 122 bytes on wire (976 bits), 122 bytes captured (976 bits)
Ethernet II, Src: RealtekS_bb:a3:a1 (00:e0:4c:bb:a3:a1), Dst: Cabletro_0c:92:1a (00:e0:63:0c:92:1a)
Internet Protocol, Src: 192.168.20.19 (192.168.20.19), Dst: 10.100.1.34 (10.100.1.34)
User Datagram Protocol, Src Port: 58753 (58753), Dst Port: 57202 (57202)
Data (80 bytes)
0000 00 03 00 01 03 01 01 04 1f 01 01 01 02 04 00 6a ...............j
0010 cf c0 03 04 00 1f 40 00 04 01 02 05 04 00 00 00 ......@.........
0020 00 06 02 00 00 07 01 00 12 01 01 06 10 7d 52 14 .............}R.
0030 b8 27 c7 58 a6 90 4a 62 55 70 4a fb 8d 07 10 7c .'.X..JbUpJ....|
0040 13 52 63 04 7d ce 11 37 84 01 e1 62 41 8f 85 ff .Rc.}..7...bA...
No. Time Source Destination Protocol Info
272 222.970211 10.100.1.34 192.168.20.19 UDP Source port: 57202 Destination port: 58753
Frame 272: 60 bytes on wire (480 bits), 60 bytes captured (480 bits)
Ethernet II, Src: Cabletro_0c:92:1a (00:e0:63:0c:92:1a), Dst: RealtekS_bb:a3:a1 (00:e0:4c:bb:a3:a1)
Internet Protocol, Src: 10.100.1.34 (10.100.1.34), Dst: 192.168.20.19 (192.168.20.19)
User Datagram Protocol, Src Port: 57202 (57202), Dst Port: 58753 (58753)
Data (4 bytes)
0000 00 04 00 01 ....
No. Time Source Destination Protocol Info
274 235.567120 10.100.1.34 192.168.20.19 TFTP Read Request, File: 7by2.cfg\000, Transfer type: octet\000, blksize\000=1448\000
Frame 274: 72 bytes on wire (576 bits), 72 bytes captured (576 bits)
Ethernet II, Src: Cabletro_0c:92:1a (00:e0:63:0c:92:1a), Dst: RealtekS_bb:a3:a1 (00:e0:4c:bb:a3:a1)
Internet Protocol, Src: 10.100.1.34 (10.100.1.34), Dst: 192.168.20.19 (192.168.20.19)
User Datagram Protocol, Src Port: 56802 (56802), Dst Port: tftp (69)
Trivial File Transfer Protocol
No. Time Source Destination Protocol Info
275 235.589588 192.168.20.19 10.100.1.34 TFTP Option Acknowledgement, blksize\000=1448\000
Frame 275: 60 bytes on wire (480 bits), 60 bytes captured (480 bits)
Ethernet II, Src: RealtekS_bb:a3:a1 (00:e0:4c:bb:a3:a1), Dst: Cabletro_0c:92:1a (00:e0:63:0c:92:1a)
Internet Protocol, Src: 192.168.20.19 (192.168.20.19), Dst: 10.100.1.34 (10.100.1.34)
User Datagram Protocol, Src Port: 30673 (30673), Dst Port: 56802 (56802)
Trivial File Transfer Protocol
No. Time Source Destination Protocol Info
276 235.595595 10.100.1.34 192.168.20.19 TFTP Acknowledgement, Block: 0
Frame 276: 60 bytes on wire (480 bits), 60 bytes captured (480 bits)
Ethernet II, Src: Cabletro_0c:92:1a (00:e0:63:0c:92:1a), Dst: RealtekS_bb:a3:a1 (00:e0:4c:bb:a3:a1)
Internet Protocol, Src: 10.100.1.34 (10.100.1.34), Dst: 192.168.20.19 (192.168.20.19)
User Datagram Protocol, Src Port: 56802 (56802), Dst Port: 30673 (30673)
Trivial File Transfer Protocol
No. Time Source Destination Protocol Info
277 235.596053 192.168.20.19 10.100.1.34 TFTP Data Packet, Block: 1 (last)
Frame 277: 122 bytes on wire (976 bits), 122 bytes captured (976 bits)
Ethernet II, Src: RealtekS_bb:a3:a1 (00:e0:4c:bb:a3:a1), Dst: Cabletro_0c:92:1a (00:e0:63:0c:92:1a)
Internet Protocol, Src: 192.168.20.19 (192.168.20.19), Dst: 10.100.1.34 (10.100.1.34)
User Datagram Protocol, Src Port: 30673 (30673), Dst Port: 56802 (56802)
Trivial File Transfer Protocol
No. Time Source Destination Protocol Info
278 235.601436 10.100.1.34 192.168.20.19 TFTP Acknowledgement, Block: 1
Frame 278: 60 bytes on wire (480 bits), 60 bytes captured (480 bits)
Ethernet II, Src: Cabletro_0c:92:1a (00:e0:63:0c:92:1a), Dst: RealtekS_bb:a3:a1 (00:e0:4c:bb:a3:a1)
Internet Protocol, Src: 10.100.1.34 (10.100.1.34), Dst: 192.168.20.19 (192.168.20.19)
User Datagram Protocol, Src Port: 56802 (56802), Dst Port: 30673 (30673)
Trivial File Transfer Protocol
>Release-Note:
>Audit-Trail:
>Unformatted:
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