Wireshark mailing list archives

Re: Transport name resolution


From: Anders Broman <a.broman () bredband net>
Date: Mon, 16 Sep 2013 21:44:34 +0200

Jeff Morriss skrev 2013-09-16 21:17:
On 09/16/13 14:57, Guy Harris wrote:

On Sep 16, 2013, at 7:20 AM, Anders Broman <anders.broman () ericsson com> wrote:

In serv_name_lookup() we call getservbyport() for ports not resolved in the IANA port list the function Seems quite expensive so my question is does it add any value or can I remove it?

At least on UN*Xes, getservbyport() does one or more of:

1) look in /etc/services, which is probably based on a (possibly-out-of-date) version of, err, umm, the IANA port list;

2) query some network service to do a lookup - and that service is probably using its own database, based on a (possibly-out-of-date) version of, err, umm, the IANA port list.

... possibly with some modifications for local use. But I imagine the number of people who actually go through the trouble to run a customized service database to be sufficiently few that it's not worth slowing everyone else down for.
I got rid of getservbyport() and added reading of the local services file perhaps the read should be removed again? I'm also wondering if service name resolution should be defaulted to off, I'm not convinced it's that useful.

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

Regards
Anders

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