#134 Slirp built-in DNS broken by 0.7.3-2

v0.7.x (release)
Henry N.
Paul Rouse

The built-in DNS on in slirp appears to have been broken by the update 0.7.3-2 to colinux-slirp-net-daemon.exe to fix bug 1995862 ("udp forwarded packets over slirp have incorrect source ip").

The issue is that the reply packets to the DNS requests now appear to come from the real DNS server, rather than the virtual one on

With the original 0.7.3 release tcpdump gives:
11:44:02.799135 IP > 38764+ A? sourceforge.net. (33)
11:44:02.809134 IP > 38764 1/0/0 A (49)

With the updated slirp daemon tcpdump shows:
11:49:45.149746 IP > 23720+ A? sourceforge.net. (33)
11:49:45.149746 IP > 23720 1/0/0 A (49)
11:49:45.149746 IP > ICMP udp port 32776 unreachable, length 85

Surely the original behaviour is what you want in the special case of DNS on

I am using a static configuration for the slirp interface, giving explicitly as the DNS server, and the address is the real DNS server which Windows is using.


  • Henry N.

    Henry N. - 2008-08-17
    • assigned_to: nobody --> henryn
  • Paul Rouse

    Paul Rouse - 2008-08-18

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    Thank you -- yes, that solves the DNS problem.

    I don't have a test for Bug #1995862 (that was someone else's) so I won't comment on that.

  • Henry N.

    Henry N. - 2008-08-19

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    File colinux-slirp-net-daemon-0.7.3-3.zip is available on SF now.

  • Henry N.

    Henry N. - 2008-08-19
    • status: open --> closed

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