TCP MSS Issue Post: 302882525

6 More Discussions You Might Find Interesting

1. Cybersecurity

Tcp/ip

!HELLO , What is the maximum number of hosts on a TCP/IP internet? plz can u help me. :rolleyes:

2. Programming

How to set the MSS programatically.

I'm sending a SYN packet and now I want to specify the MSS (The maximum segment size option in a TCP packet ) through it. How can I do that? Also, I'm not getting a SYN-ACK back from the remote host. TCPDUMP tells me that my packet is good and is a SYN. Then, why don't I get back the SYN-ACK? I...

3. Linux

Security issue with TCP SYN packets on Linux

Hi all, A security scanner has been done on a linux server and have found that The remote host does not discard RCP SYN packets which have the FIN flag set. It tells that I need to request a patch which I haven't found yet. I have Red Hat Linux release 7.0 (Guinness) Kernel 2.2.16-22...

4. IP Networking

Tcp\ip

I have written a TCP/IP client and server program. The client sends a message to the server and then the server sends a file back to the client. The client reads the buffer and stores it another file in the client side. I need to know what are the various exceptions that I need to handle in...

5. IP Networking

Could a tcp issue be causing a null pointer exception?

The client's app gets a 'suspend error' which they say is due to a null pointer exception. Application people say nothing's wrong with the app. Network people say the network's fine. I'm supposed to see what's wrong with the system to be causing this error. I checked the NIC card settings, which...

6. Solaris

Too much TCP retransmitted and TCP duplicate on server Oracle Solaris 10

I have problem with oracle solaris 10 running on oracle sparc T4-2 server. Os information: 5.10 Generic_150400-03 sun4v sparc sun4v Output from tcpstat.d script TCP bytes: out outRetrans in inDup inUnorder 6833763 7300 98884 0...

LEARN ABOUT ULTRIX

synos

synos(1)							Mail Avenger 0.8.3							  synos(1)

NAME

       synos - guess operating system from TCP SYN fingerprint

SYNOPSIS

       synos [--mtu mtu] [--db path] syn-fingerprint

DESCRIPTION

       synos takes a SYN fingerprint, in the format described for the CLIENT_SYNFP environment variable in the avenger(1) man page, and outputs a
       guess as to the type of the client operating system.  synos makes use of the OpenBSD SYN fingerprint database (which is also repackaged
       with Mail Avenger).

   OPTIONS
       --mtu val
	   Certain operating systems set the initial TCP window size based on the maximum transmission unit, or MTU, of the network.  For such
	   operating systems, synos usually checks the window size using both the client's MSS option plus 40 bytes (for TCP and IP headers), or a
	   hard-coded MTU, which defaults to 1,500 bytes.  If either value works, the fingerprint is considered to match the operating system.
	   You can change the value 1,500 by specifying this option.  A value of 0 tells synos to use only the value derived from the MSS option.

       --db file
	   Specifies an alternate location for the SYN fingerprint database.

FILES

       /usr/local/share/pf.os
	   Default location of SYN fingerprint database.

SEE ALSO

       avenger(1), asmtpd(8)

       The Mail Avenger home page: <http://www.mailavenger.org/>.

       The OpenBSD home page: <http://www.openbsd.org/>.

BUGS

       The operating system type is determined by heuristics that are not always reliable.  Moreover, not all operating systems can be
       distinguished.  The database may not even contain a client's particular operating system and version.

       It is not hard to fool synos deliberately by changing TCP socket options or injecting raw packets onto the network.

AUTHOR

       David Mazieres

Mail Avenger 0.8.3						    2012-04-05								  synos(1)