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TCP: Treason uncloaked!


I am having redhat linux 7.2 server . while typing the dmesg in the shell i am getting the following message.

# dmesg

TCP: Treason uncloaked! Peer shrinks window 2070208664:2070208728. Repaired.
TCP: Treason uncloaked! Peer shrinks window 2070208664:2070208728. Repaired.
TCP: Treason uncloaked! Peer shrinks window 2811533730:2811533794. Repaired.

That server is co-located server that is remote host.

I am trying to access the websites in my client system which is hosted in the server.

The problem is the site is not clear. some times it is displaying well. some times not clear.

It is displaying with <tag> <html>

What is the solution. Any ideas ?

Kindly help me in this regard.


Loganathan Natarajan
Loganathan Natarajan
1 Solution
I'd say there's two different issues here and they probably aren't related. The TCP errors would tend to point to a problem with the ssh client/system you are using. If I understand your problem with the web site it sounds like some of the data that you expect to be rendered by a browser is showing up as the raw HTML code. That would point to a problem with the HTML pages themselves, or if they are being generated by a scripting language (PHP, Perl, etc) with the code that generates the page.
The reason Linux is printing such messages is because your client guy is shrinking the TCP Window to 0, and the server has something to retransmit. There is something seriously wrong with your client's  stack. Which Stack/OS are you using on he client side, and which browser?

That could explain your browser showing some html tags as the server fails to send the whole page across and based on what browser you are using it is failing to parse it out.
As my predecessors have said, the error means a broken stack on the client side. Or maybe an (pretty silly) attack.
Or a new firewall policy from your ISP or a broken device along the way (although I think this is quite unlikely).

1. do you find any other errors linked to the TCP/IP stack ? Something about wrong checksums ?
2. Are you using any mobile devices ? Some of those seem to have funny ideas about TCP/IP.
3. Do you recognize the IP ( ?
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The IP does not appear to be a valid registered IP to anyone, and it is not an 'internal network ip' as far as I'm aware, therefore, I'd treat this particular incident suspiciously.

Unfortunately, I can't reproduce this error, even with a RedHat 7.2 Server available to me.

I suspect that this message was as a result of an attempted attack on your sshd. As a result of the number of packets being sent, you attempts to access anything else were messes with, and unable to complete. Therefore I recommend:

a.  Check whether you have sshd running. If you don't need it, then get rid of it.
b. If you do need sshd, then check version number (rpm -q sshd), and go here:


Check whether your sshd needs to be updated, and update as required.


Of course if you are not using sshd - just bloke port 22 with your firwall:)
> .. then check version number (rpm -q sshd),
please don't rely on rpm (or packages anyhow) but use
   sshd -V
to get the real version.
Think secure, not guessing ;-)
The client is "shrinking the TCP Window to 0" and it cause the problem. So, what to do to prevent this issue ?
logudotcom, could you please explain your grading
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Just to comment on pjedmond's remark that you should treat this suspiciously... I'm not so sure.

 -- the original IP address is a _valid_ IP address, with a registered operator in India.
so it's not as suspicious as a packet coming from an unallocated source.

inetnum: -
netname:      SPACENET
descr:        HCL Comnet, Internmet Service Provider on VSATs, India
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