On 09/16/13 16:04, Guy Harris wrote:

On Sep 16, 2013, at 12:44 PM, Anders Broman <[email protected]> wrote:

I got rid of getservbyport() and added reading of the local services file 
perhaps the read should be removed again?

"Local services file" as in "/etc/services" on UN*X and its equivalent on Windows 
(C:\winnt\system32\drivers\etc\services?), or "local services file" as in "the services file that's distributed as 
part of Wireshark"?  We should continue to use the latter; the aforementioned "modifications for local use" could 
be made to that file as well.

I'm also wondering if service name resolution should be defaulted to off, I'm 
not convinced it's that useful.

Using the IANA port list is the reason why we get people asking why, for example, they're 
seeing "dssiapi" traffic on their network, just because something happens to be 
using port 1265.  (I picked that example somewhat at random, but we *do* get that asked 
at times.)

Should we, instead, look the port number up in the "tcp.port" or "udp.port" (or 
"sctp.port") dissector table and, if it finds a dissector handle, look up the short name of the 
protocol for that dissector handle and use that?  That means that:

        1) we're using the name Wireshark uses elsewhere for the protocol (e.g., "DNS" 
rather than "domain");

        2) if we don't have a dissector registered for that port, we don't show 
a protocol name (which is arguably a feature rather than a bug, as the traffic 
isn't necessarily for the protocol linked with the port number given in the 
IANA list, and this means that if we're not going to dissect the traffic as 
that protocol we're probably not going to claim it's that protocol, which I see 
as a Good Thing).

If we decide to have it default off perhaps we shouldn't default to write
User Datagram Protocol, Src Port: 60000 (60000), Dst Port: 13868 (13868) but 
rather
User Datagram Protocol, Src Port: 60000 , Dst Port: 13868

Yes, and the same applies for network addresses, if we're not already doing 
that.

Defaulted to off (i.e., a preference) or off by code?

If we have a preference (for services or network addresses) I think keeping the same format:

User Datagram Protocol, Src Port: 60000 (60000), Dst Port: 13868 (13868)

is actually a good thing because then tshark output parsers don't have to worry about whether or not the preference is set.

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