Wireshark dissector plugin for EPICS CA and PVA protocols

Tested with wireshark 1.2.11, 1.8.2, 1.10.8, 2.2.6, 2.6.0, and 3.4.10. Works on RHEL 7.4 (wireshark 1.10.14).

Using

Only the file ca.lua is needed. Then start wireshark with

wireshark -X lua_script:/path/to/ca.lua

and/or

wireshark -X lua_script:/path/to/pva.lua

More than one -X argument may be passed to load both plugins.

Status

The pva.lua plugin decodes PVA traffic on standard (TCP/5075 and UDP/5076) and non-standard ports.

The ca.lua plugin does general decoding of CA UDP and TCP traffic on the standard ports (5064 and 5065). It does TCP segment reassembly for large messages.

The CA protocol provides no easy way to distinguish client and server messages without observing the start of the connection. Thus this plugin can not fully decode all messages. Currently only some messages are fully decoded. Others decode with only generic field names.

Reporting bugs

Bug reports are welcome (and patches more so).

Send to "Michael Davidsaver" [email protected] or open a github issue. Please include repository revision, as well as wireshark and lua versions.

If possible, please include a (filtered) packet capture file which will trigger the error.

Note that the PVA dissector triggers bug 10233 with wireshark 1.12.1, which is known to be fixed with 2.0.

Setup

To automatically load the CA and/or PVA dissectors instead of using the -X argument.

On RHEL systems, the wireshark config directory is at /usr/share/wireshark/. If the file /usr/share/wireshark/init.lua doesn't exist, install the package wireshark-devel.

Edit /etc/wireshark/init.lua and remove or comment out the line about disabling LUA support ("disable_lua = true"). You may also need to change the line "run_user_scripts_when_superuser = false" depending on how you run wireshark.

Next copy the file ca.lua from this repository to /etc/wireshark/.

Then add either or both lines to the end of init.lua.

dofile("ca.lua")
dofile("pva.lua")

If all goes well the string "Loaded CA" and/or "Loaded PVA" will be printed to the console when wireshark starts.

To install this for a single user create $HOME/.wireshark/init.lua with a single line "dofile("ca.lua")" and place ca.lua in this directory.

tshark

Dissectors may also be used with the CLI interface tshark. For example, the following prints all CA decode information in test/cabeacon.cap.

tshark -r test/cabeacon.cap \
 -X lua_script:ca.lua \
 -PO ca \
 'ca'

And with PVA:

tshark -r test/pva-beacon.pcapng.gz \
 -X lua_script:ca.lua \
 -PO pva \
 'pva'

Note that both decoders can be loaded simultaneously:

tshark \
 ...
 -X lua_script:ca.lua \
 -X lua_script:pva.lua \
 -PO ca,pva \
 'ca || pva'