FreeBSD 7.1-PRERELEASE Trouble

[Jeremy Chadwick]

On Mon, Sep 08, 2008 at 08:51:39AM -0700, Jeremy Chadwick wrote:
> On Mon, Sep 08, 2008 at 07:13:35PM +0400, Dmitry Rybin wrote:
> > PF doesn't block some IP!!!!
> > 
> > === pf.conf ===
> > 
> > ext_if="bge0"
> > table <dnsflood> { 78.107.71.38 89.179.195.34 }
> > 
> > block quick from <dnsflood>
> > pass out
> > pass in
> > === pf.conf ===
> > 
> > # pfctl -e -f /etc/pf.conf
> > 
> > # tcpdump -netxi bge0 host 89.179.195.34
> > 00:1a:a1:69:35:43 > 00:1c:c4:81:2f:9e, ethertype IPv4 (0x0800), length 69:
> > 89.179.195.34.2357 > 195.14.50.21.53: 35869+ A? emils.com. (27)
> >         0x0000:  4500 0037 3034 0000 3811 4089 59b3 c322
> >         0x0010:  c30e 3215 0935 0035 0023 0314 8c1d 0100
> >         0x0020:  0001 0000 0000 0000 0565 6d69 6c73 0363
> >         0x0030:  6f6d 0000 0100 01
> > 00:1c:c4:81:2f:9e > 00:00:0c:07:ac:00, ethertype IPv4 (0x0800), length 84:
> > 195.14.50.21.53 > 89.179.195.34.2357: 48025 ServFail 0/0/1 (42)
> >         0x0000:  4500 0046 84a8 0000 4011 0000 c30e 3215
> >         0x0010:  59b3 c322 0035 0935 0032 c7de bb99 8182
> >         0x0020:  0001 0000 0000 0001 0377 7777 0565 6d69
> >         0x0030:  6c73 0363 6f6d 0000 0100 0100 0029 1000
> >         0x0040:  0000 0000 0000
> > 00:1c:c4:81:2f:9e > 00:00:0c:07:ac:00, ethertype IPv4 (0x0800), length 73:
> > 195.14.50.21.53 > 89.179.195.34.2357: 22012 ServFail 0/0/0 (31)
> >         0x0000:  4500 003b 84a9 0000 4011 0000 c30e 3215
> >         0x0010:  59b3 c322 0035 0935 0027 3dbc 55fc 8182
> >         0x0020:  0001 0000 0000 0000 0377 7777 0565 6d69
> >         0x0030:  6c73 0363 6f6d 0000 0100 01
> > 00:1c:c4:81:2f:9e > 00:00:0c:07:ac:00, ethertype IPv4 (0x0800), length 69:
> > 195.14.50.21.53 > 89.179.195.34.2357: 35869 ServFail 0/0/0 (27)
> >         0x0000:  4500 0037 84ac 0000 4011 0000 c30e 3215
> >         0x0010:  59b3 c322 0035 0935 0023 8291 8c1d 8182
> >         0x0020:  0001 0000 0000 0000 0565 6d69 6c73 0363
> >         0x0030:  6f6d 0000 0100 01
> > 00:1a:a1:69:35:43 > 00:1c:c4:81:2f:9e, ethertype IPv4 (0x0800), length 73:
> > 89.179.195.34.2357 > 195.14.50.21.53: 48025+ A? www.emils.com. (31)
> >         0x0000:  4500 003b 3035 0000 3811 4084 59b3 c322
> >         0x0010:  c30e 3215 0935 0035 0027 58a1 bb99 0100
> >         0x0020:  0001 0000 0000 0000 0377 7777 0565 6d69
> >         0x0030:  6c73 0363 6f6d 0000 0100 01
> > 00:1c:c4:81:2f:9e > 00:00:0c:07:ac:00, ethertype IPv4 (0x0800), length 73:
> > 195.14.50.21.53 > 89.179.195.34.2357: 48025 ServFail 0/0/0 (31)
> >         0x0000:  4500 003b 84ae 0000 4011 0000 c30e 3215
> >         0x0010:  59b3 c322 0035 0935 0027 d81e bb99 8182
> >         0x0020:  0001 0000 0000 0000 0377 7777 0565 6d69
> >         0x0030:  6c73 0363 6f6d 0000 0100 01
> > 
> > tcpdump -netxi bge0 host 78.107.71.38
> > tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
> > listening on bge0, link-type EN10MB (Ethernet), capture size 96 bytes
> > 00:1a:a1:69:35:43 > 00:1c:c4:81:2f:9e, ethertype IPv4 (0x0800), length 94:
> > 78.107.71.38.37367 > 195.14.50.21.53: 38168+ A?
> > nc-71-51-232-31.dhcp.embarqhsd.net. (52)
> >         0x0000:  4500 0050 ae4f 4000 3b11 0699 4e6b 4726
> >         0x0010:  c30e 3215 91f7 0035 003c e6ca 9518 0100
> >         0x0020:  0001 0000 0000 0000 0f6e 632d 3731 2d35
> >         0x0030:  312d 3233 322d 3331 0464 6863 7009 656d
> >         0x0040:  6261 7271 6873 6403 6e65 7400 0001 0001
> > 00:1a:a1:69:35:43 > 00:1c:c4:81:2f:9e, ethertype IPv4 (0x0800), length 89:
> > 78.107.71.38.37368 > 195.14.50.21.53: 50276+ A?
> > 166.156.122.89.bl.spamcop.net. (47)
> >         0x0000:  4500 004b ae68 4000 3b11 0685 4e6b 4726
> >         0x0010:  c30e 3215 91f8 0035 0037 18d5 c464 0100
> >         0x0020:  0001 0000 0000 0000 0331 3636 0331 3536
> >         0x0030:  0331 3232 0238 3902 626c 0773 7061 6d63
> >         0x0040:  6f70 036e 6574 0000 0100 01
> > 
> > Add to pf.conf
> > block quick from 89.179.195.34 - same, doesn't work.
> > 
> > May be trouble in config?
> 
> Please show the output of "pfctl -s rules".

Also, you might want to ensure the entries in the table are getting hit:

pfctl -T show -t dnsflood -v

If the counters for Block are getting incremented, then the rule is
working.

What might be happening is pf has a state table entry which is allowing
the machine in table <dnsflood> to still continue sending packets to it,
on the same TCP/UDP socket as before.

You can verify this by using "pfctl -s state | grep ip"

To remove the states, use pfctl -k ip.

-- 
| Jeremy Chadwick                                jdc at parodius.com |
| Parodius Networking                       http://www.parodius.com/ |
| UNIX Systems Administrator                  Mountain View, CA, USA |
| Making life hard for others since 1977.              PGP: 4BD6C0CB |