You're right, and I see my error. That is frustrating because I have no idea why it doesn't work with the offset specified then.<br><br><div class="gmail_quote">On Fri, Feb 24, 2012 at 4:10 AM, Luca Farflame Fabbro <span dir="ltr"><<a href="mailto:farflame@cybergames.it">farflame@cybergames.it</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="word-wrap:break-word"><div>Try this command</div>tcpdump -c 4 -nnvvvXS dst port 28960<div>where port is the port that you want to monitor</div>
<div>should be something like</div><div><br></div><div><div><font face="'Courier New'"> 0x0000: 4500 002b 35b3 0000 7511 179b b612 80ad E..+5...u.......</font></div><div><font face="'Courier New'"> 0x0010: c0a8 010c 7012 7120 0017 0000 ffff ffff ....p.q.........</font></div>
<div><font face="'Courier New'"> 0x0020: 6765 7473 7461 7475 730a 0000 0000 getstatus.....</font></div></div><div><div class="h5"><div><br></div><div>On Feb 24, 2012, at 9:54 AM, Geoff Goas wrote:</div>
<div><div><br><blockquote type="cite">That is strange, because if I use those values, it does not work. If I use "--from 31" alone, then it works. As soon as I change that to 32, it stops working. When I inspect the packets in Wireshark, the "getstatus" string starts at offset 48 if counting from 1. Would there be a way for iptables to print to log what it sees in the specified offset range?<br>
<br><div class="gmail_quote">On Fri, Feb 24, 2012 at 3:28 AM, Luca Farflame Fabbro <span dir="ltr"><<a href="mailto:farflame@cybergames.it" target="_blank">farflame@cybergames.it</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div style="word-wrap:break-word">It doesn't matter the length of the packet. <div>That rule will try to find the string "gestatus" starting at position 32 bytes from start of packet and searching for it at maximum at position 41.</div>
<div>The Q3 protocol for that command expects the string to be in that range.<br><div> <br><div><div><div>On Feb 24, 2012, at 1:11 AM, Geoff Goas wrote:</div><br></div><blockquote type="cite"><div>Is the offset range of 32-41 based on a 60-byte packet?<br>
<br><div class="gmail_quote">On Thu, Feb 23, 2012 at 10:34 AM, Marco Padovan <span dir="ltr"><<a href="mailto:evcz@evcz.tk" target="_blank">evcz@evcz.tk</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">
<div bgcolor="#FFFFFF" text="#000000">
iptables -A INPUT -p udp -m string --string "getstatus"
--algo bm --from 32 --to 41 -j DROP<br>
<br></div></blockquote></div></div><div>-- <br><i><b><font size="1"><span style="font-family:tahoma,sans-serif">Geoff Goas</span><br style="font-family:tahoma,sans-serif"><span style="font-family:tahoma,sans-serif">Systems Engineer</span></font></b></i><br>
<br>
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<br></blockquote></div><br><br clear="all"><br>-- <br><i><b><font size="1"><span style="font-family:tahoma,sans-serif">Geoff Goas</span><br style="font-family:tahoma,sans-serif"><span style="font-family:tahoma,sans-serif">Systems Engineer</span></font></b></i><br>
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<br></blockquote></div><br><br clear="all"><br>-- <br><i><b><font size="1"><span style="font-family:tahoma,sans-serif">Geoff Goas</span><br style="font-family:tahoma,sans-serif"><span style="font-family:tahoma,sans-serif">Systems Engineer</span></font></b></i><br>
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