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Tshark LUA Script

asked 2021-02-14 01:03:28 +0000

moraist gravatar image

updated 2021-02-16 20:32:52 +0000

cmaynard gravatar image

I am trying to run a Lua script (filtcols.lua) from tshark in the same way as I do from the Wireshark GUI (filtcols.info contains "string"), but I am getting a syntax error. How can I do that in the tshark?

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filtcols is a work around for fields that are available in tshark but not in wireshark.

Any reason for not using the _ws.col fields in tshark?

$ tshark -r captureFile.pcap -T fields -e _ws.col.Protocol -e _ws.col.Info

Chuckc gravatar imageChuckc ( 2021-02-14 03:50:06 +0000 )edit

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answered 2021-02-16 22:00:37 +0000

cmaynard gravatar image

As Chuck mentions, the filtcols.lua script shouldn't be needed with tshark; however, if you really want to use it, then the following modified version of the filtcols.lua script does seem to work with tshark too. I'll let Chuck decide if it's worth updating on the Wireshark wiki or not, since it's his creation and I only tweaked it.

-- filtcols.lua
-- similar to _ws.col.protocol in tshark

local filtcols_info =
{
    version = "1.0.1",
    author = "Chuck Craft",
    description = "Support filtering on Protocol and Info columns",
}

set_plugin_info(filtcols_info)

-- we create a "protocol" for our tree
local filtcols_p = Proto("filtcols","Filterable Protocol/Info columns")

-- we create our fields
local col_protocol_field = ProtoField.string("filtcols.protocol", "Protocol column")
local col_info_field = ProtoField.string("filtcols.info", "Info column")

-- we add our fields to the protocol
filtcols_p.fields = { col_protocol_field, col_info_field }

-- variables to persist across all packets
local pkt_data = {} -- indexed per packet

pkt_data.protocol = {}
pkt_data.info = {}

-- let's do it!
function filtcols_p.dissector(tvb, pinfo, tree)

    -- Protocol Column
    local cols_protocol = tostring(pinfo.cols.protocol)
    if cols_protocol ~= "(protocol)" then
        --print (" Frame: " .. pinfo.number .. "; Protocol: " .. cols_protocol)
        if pkt_data.protocol[pinfo.number] == nil then
            pkt_data.protocol[pinfo.number] = cols_protocol
        end
    end
    tree:add(col_protocol_field, pkt_data.protocol[pinfo.number])

    -- Info Column
    local cols_info = tostring(pinfo.cols.info)
    if cols_info ~= "(info)" then
        --print (" Frame: " .. pinfo.number .. "; Info: " .. cols_info .. "\n")
        if pkt_data.info[pinfo.number] == nil then
            pkt_data.info[pinfo.number] = cols_info
        end
    end
    tree:add(col_info_field, pkt_data.info[pinfo.number])
end

-- then we register filtcols_p as a postdissector
register_postdissector(filtcols_p)
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Asked: 2021-02-14 01:03:28 +0000

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Last updated: Feb 16