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Bug #895

closed

response: rst packet bug

Added by Victor Julien over 10 years ago. Updated over 10 years ago.

Status:
Closed
Priority:
Normal
Assignee:
Target version:
Affected Versions:
Effort:
Difficulty:
Label:

Description

Reported privately:

In the function "RejectSendLibnet11L3IPv4TCP", why add 1 to ack?
It breaks the TCP protocol.
    /* build the package */
    if ((libnet_build_tcp (
                    lpacket.sp,            /* source port */
                    lpacket.dp,            /* dst port */
                    lpacket.seq,           /* seq number */
                    lpacket.ack+1,           /* ack number */
                    TH_RST|TH_ACK,         /* flags */
                    lpacket.window,        /* window size */
                    0,                     /* checksum */
                    0,                     /* urgent flag */
                    LIBNET_TCP_H,          /* header length */
                    NULL,                  /* payload */
                    0,                     /* payload length */
                    c,                     /* libnet context */
                    0)) < 0)               /* libnet ptag */

Actions #1

Updated by Victor Julien over 10 years ago

The rst stuff is not in good shape. In my tests the observations in the private report are correct. The +1 doesn't make sense.

A few other things:
- rst seems unreliable even fixing this ticket
- rst is not sent out of the monitor interface. In my test eth0 is normally connected, eth1 is the (ip-less) monitor interface. RST seem to be coming from eth0 (at least they have the mac from eth0).

Not sure why the +1 was added. It was part of a FreeBSD/IPFW patch.

Actions #2

Updated by Eric Leblond over 10 years ago

Ipv6 reset is also missing.

Actions #3

Updated by Eric Leblond over 10 years ago

  • % Done changed from 0 to 80
Actions #4

Updated by Eric Leblond over 10 years ago

  • Status changed from Assigned to Closed
  • % Done changed from 80 to 100
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