I wish to display the TCP flags as a column in the display window. I add a new column from the Preferences but there is no field type for TCP flags (or more likely - I can't find it). How do I display the TCP flag as a column? Microsoft Network Monitor has an option for this (but can't display the time as seconds since epoch 01-01-1970 which I need). Are there any other .cap file viewers which will allow me to display both these columns?
We can add a custom column and put tcp.flags as the field name.
Related
I am using wireshark to decode gsm packets. Wireshark picks up all communication at that frequency and decodes it.
Overview of the packets obtained.
Now in the system information 5 packet, we have the required parameter.Details of system information 5 packet
I wish to write a code such that if there is only a single value in the last entry of the packet i.e. the neighbour list, an alert inform of a pop up message or something is generated.
These packets have to captured and processed in real time.
I have installed pyshark but cant figure out how to move forward.
Please help
I can only give a partial answer, which is how to detect if there's only a single value or not. My suggestion is to use tshark and then post-process the data using another tool, such as wc. For example:
tshark -i lo -Y "gsm_a.rr.arfcn_list" -T fields -e gsm_a.rr.arfcn_list | wc -w
If the result is 1, then there's only 1 entry in the list.
How you generate an alert from this, I'm not sure.
According to this link:
https://learn.microsoft.com/en-us/microsoft-edge/devtools-guide/network
Edge can do a maximum of 6 simultaneous TCP connections per hostname.
In IE it was possible to change this. Can I change this for Edge and where is the registry can this be found (this is how it was done in IE)?
Try to follow steps below to disable the connection limit.
(1) Type Regedit in Run window to open registry editor.
(2) navigate to location below.
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\Tcpip\Parameters
(3) Add new DWORD(32 bit) value.
(4) Name it as EnableConnectionRateLimiting
(5) Double click on it and set it value to 0.
Note:- User can also set the maximum desired limit for connections.
I previously posted a question entitled "Writing a Wireshark Dissector to Count Number of TCP Flows." I got some feedback to use Lua/Tap instead so I set out to write one but I need assistance with the code. I currently have the following functions that a tap must have:
Listener.new,
listener.packet,
listener.draw,
listener.reset.
To get a better understanding of what I want to do, please review my previous question here:
Writing a Wireshark dissector to count number of TCP flows
My new question is, would I need to write a code to do the equivalent of the tshark's command:
tshark -r 1min.pcap -q -n -z conv,tcp
in Lua/Tap to extract the statistics information first before I proceed to write code to count the TCP flows? Or all I need to do is write a code in Lua/Tap to to extract the TCP flow count. In either case, can someone help me with the code? I've search the web but can't find an example close to what I'm looking for so I can customize to suit what I'm trying to achieve. Thanks.
I don't have time to write code for you, but here's some information copied from an edit I made to the answer to your other question:
The C structure passed to TCP taps for each packet is:
/* the tcp header structure, passed to tap listeners */
typedef struct tcpheader {
guint32 th_seq;
guint32 th_ack;
gboolean th_have_seglen; /* TRUE if th_seglen is valid */
guint32 th_seglen;
guint32 th_win; /* make it 32 bits so we can handle some scaling */
guint16 th_sport;
guint16 th_dport;
guint8 th_hlen;
guint16 th_flags;
guint32 th_stream; /* this stream index field is included to help differentiate when address/port pairs are reused */
address ip_src;
address ip_dst;
/* This is the absolute maximum we could find in TCP options (RFC2018, section 3) */
#define MAX_TCP_SACK_RANGES 4
guint8 num_sack_ranges;
guint32 sack_left_edge[MAX_TCP_SACK_RANGES];
guint32 sack_right_edge[MAX_TCP_SACK_RANGES];
} tcp_info_t;
So, for C-language taps, the "data" argument to the tap listener's "packet" routine points to a structure of that sort.
For Lua taps, the "tapinfo" table passed as the third argument to the tap listener's "packet" routine is described as "a table of info based on the Listener's type, or nil.". For a TCP tap, the entries in the table include all the fields in that structure except for sack_left_edge and sack_right_edge; the keys in the table are the structure member names.
The th_stream field identifies the connection; each time the TCP dissector finds a new connection, it assigns a new value. As the comment indicates, "this stream index field is included to help differentiate when address/port pairs are reused", so that if a given connection is closed, and a later connection uses the same endpoints, the two connections have different th_stream values even though they have the same endpoints.
So you'd have a table using the th_stream value as a key. The table would store the endpoints (addresses and ports) and counts of packets and bytes in each direction. For each packet passed to the listener's "packet" routine, you'd look up the th_stream value in the table and, if you don't find it, you'd create a new entry, starting the counts off at zero, and use that new entry; otherwise, you'd use the entry you found. You'd then figure out whether the packet was going from A to B or B to A, and increase the appropriate packet count and byte count.
You'd also keep track of the time stamp. For the first packet, you'd store the time stamp for that packet. For each packet, you'd look at the time stamp and, if it's one minute or more later than the stored time stamp, you'd:
dump out the statistics from the table of connections;
empty out the table of connections;
store the new packet's time stamp, replacing the previous stored time stamp.
I have a very large tcpdump file that I split into 1 minute intervals. I am able to use tshark to extract TCP statistics for each of the 1 minute files using a loop code and save the results as a CSV file so I can perform further analysis in Excel. Now I want to be able to count the number of TCP flows in each 1 minute file for all the 1 minute files and save the data in a CSV file. A TCP flow here represents group of packets going from a specific source to a specific destination. Each flow has statistics such as source IP, dest IP, #pcakets from A->B, #bytes from A->B, #packets from B->A, #bytes from B->A, total packets, total bytes, etc. And I just want to count the number of TCP flows in each of the 1 minute files. From what I’ve read so far, it seems I need to create a dissector to do that. Can anyone give me pointers or code on how to get started? Thanks.
Tshark has a command to dump all of the necessary information: tshark -qz conv,tcp -r FILE. This writes one line per flow (plus a header and footer) so to count the flows just count the lines and subtract the header/footer.
Not a dissector, but a tap. See the Wireshark README.tapping document, and see the TShark iousers tap for a, sadly, not at all simple example in C.
It's also possible to write taps in Lua; see, for example, the Lua/Taps page in the Wireshark Wiki and the Lua Support in Wireshark section of the Wireshark User's Manual.
The C structure passed to TCP taps for each packet is:
/* the tcp header structure, passed to tap listeners */
typedef struct tcpheader {
guint32 th_seq;
guint32 th_ack;
gboolean th_have_seglen; /* TRUE if th_seglen is valid */
guint32 th_seglen;
guint32 th_win; /* make it 32 bits so we can handle some scaling */
guint16 th_sport;
guint16 th_dport;
guint8 th_hlen;
guint16 th_flags;
guint32 th_stream; /* this stream index field is included to help differentiate when address/port pairs are reused */
address ip_src;
address ip_dst;
/* This is the absolute maximum we could find in TCP options (RFC2018, section 3) */
#define MAX_TCP_SACK_RANGES 4
guint8 num_sack_ranges;
guint32 sack_left_edge[MAX_TCP_SACK_RANGES];
guint32 sack_right_edge[MAX_TCP_SACK_RANGES];
} tcp_info_t;
So, for C-language taps, the "data" argument to the tap listener's "packet" routine points to a structure of that sort.
For Lua taps, the "tapinfo" table passed as the third argument to the tap listener's "packet" routine is described as "a table of info based on the Listener's type, or nil.". For a TCP tap, the entries in the table include all the fields in that structure except for sack_left_edge and sack_right_edge; the keys in the table are the structure member names.
The th_stream field identifies the connection; each time the TCP dissector finds a new connection, it assigns a new value. As the comment indicates, "this stream index field is included to help differentiate when address/port pairs are reused", so that if a given connection is closed, and a later connection uses the same endpoints, the two connections have different th_stream values even though they have the same endpoints.
So you'd have a table using the th_stream value as a key. The table would store the endpoints (addresses and ports) and counts of packets and bytes in each direction. For each packet passed to the listener's "packet" routine, you'd look up the th_stream value in the table and, if you don't find it, you'd create a new entry, starting the counts off at zero, and use that new entry; otherwise, you'd use the entry you found. You'd then figure out whether the packet was going from A to B or B to A, and increase the appropriate packet count and byte count.
You'd also keep track of the time stamp. For the first packet, you'd store the time stamp for that packet. For each packet, you'd look at the time stamp and, if it's one minute or more later than the stored time stamp, you'd:
dump out the statistics from the table of connections;
empty out the table of connections;
store the new packet's time stamp, replacing the previous stored time stamp.
Is there a way to capture only the data layer and disregard the upper layers in wireshark? If not, is there a different packet dump utility that can do this? PREFERABLY 1 file per packet!
What I am looking for: A utility that dumps only the data (the payload) layer to a file.
This is programming related...! What I really want to do is to compare all of the datagrams in order to start to understand a third party encoding/protocol. Ideally, and what would be great, would be a hex compare utility that compares multiple files!
You should try right-clicking on a packet and select "Follow TCP Stream". Then you can save the TCP communication into a raw file for further processing. This way you won't get all the TCP/IP protocoll junk.
There is a function to limit capture size in Wireshark, but it seems that 68bytes is the smallest value. There are options to starting new files after a certain number of kilo, mega, gigabytes, but again the smallest is 1-kilobyte, so probably not useful.
I would suggest looking at the pcap library and rolling your own. I've done this in the past using the PERL Net::Pcap library, but it could easily be done it other languages too.
If you have Unix/Linux available you might also look into tcpdump. You can limit amount of data captured with -s. For example "-s 14" would typically get you the Ethernet header, which I assume is what you mean by the datalink layer. There are also options for controlling how often files are created by specifying file size with -C. So theoretically if you set the file size to the capture size, you'll get one file per packet.
Using tshark I was able to print data only, by decoding as telnet and printing field telnet.data
tshark -r file.pcap -d tcp.port==80,telnet -T fields -e telnet.data
GET /test.js HTTP/1.1\x0d\x0a,User-Agent: curl/7.35.0\x0d\x0a,Host: 127.0.0.1\x0d\x0a,Accept: */*\x0d\x0a,\x0d\x0a
HTTP/1.1 404 Not Found\x0d\x0a,Server: nginx/1.4.6 (Ubuntu)\x0d\x0a,Date: Fri, 15 Jan 2016 11:32:58 GMT\x0d\x0a,Content-Type: text/html\x0d\x0a,Content-Length: 177\x0d\x0a,Connection: keep-alive\x0d\x0a,\x0d\x0a,<html>\x0d\x0a,<head><title>404 Not Found</title></head>\x0d\x0a,<body bgcolor=\"white\">\x0d\x0a,<center><h1>404 Not Found</h1></center>\x0d\x0a,<hr><center>nginx/1.4.6 (Ubuntu)</center>\x0d\x0a,</body>\x0d\x0a,</html>\x0d\x0a
Not perfect but it was good enough for what I needed, I hope it helps some one.