Underscore in Host field
Duane D. Weaver
Does FAL allow for the use of the underscore character in the host
portion of the address?
How about ver 2?
**************
Duane D. Weaver
LISTSERV Postmaster
Senior Systems Programmer
VM Support Group
Ohio State University
Daniel M. Barton
>
> Does FAL allow for the use of the underscore character in the host
> portion of the address?
>
> How about ver 2?
>
Underscores are not allowed in TCP/IP hostnames, here are the rules
from RFC 952. Note: hostnames can now start with a numeric character
(such a "3com"), this rule was amended in RFC 1123. I'd recommend you
not use underscores as many TCP/IP implementations (including FAL),
explicitly check a hostname to see if its legal or not.
ASSUMPTIONS
1. A "name" (Net, Host, Gateway, or Domain name) is a text string up
to 24 characters drawn from the alphabet (A-Z), digits (0-9), minus
sign (-), and period (.). Note that periods are only allowed when
they serve to delimit components of "domain style names". (See
RFC-921, "Domain Name System Implementation Schedule", for
background). No blank or space characters are permitted as part of a
name. No distinction is made between upper and lower case. The first
character must be an alpha character. The last character must not be
a minus sign or period. A host which serves as a GATEWAY should have
"-GATEWAY" or "-GW" as part of its name. Hosts which do not serve as
Internet gateways should not use "-GATEWAY" and "-GW" as part of
their names. A host which is a TAC should have "-TAC" as the last
part of its host name, if it is a DoD host. Single character names
or nicknames are not allowed.
Eric Thomas
said:
> 1. A "name" (Net, Host, Gateway, or Domain name) is a text string up
> to 24 characters drawn from the alphabet (A-Z), digits (0-9), minus
> sign (-), and period (.).
24 characters? I wonder how much of Germany that leaves out ;-) This RFC
(1985) must be outdated. RFC822 certainly allows underscores in
hostnames, so if anyone complains, it should be the name server.
Eric
Mike Friedman (510) 642-1410
>
> ... RFC822 certainly allows underscores in
>hostnames, so if anyone complains, it should be the name server.
>
one to do? We have this problem here also: dozens of campus workstations
have underscores in their names, and FAL's MAKESITE always truncates them.
Daniel M. Barton
> On Mon, 6 Apr 1992 16:00:12 EDT "Daniel M. Barton"
> <DMBA...@RALVMM.VNET.IBM.COM said:
>
> > 1. A "name" (Net, Host, Gateway, or Domain name) is a text string up
> > to 24 characters drawn from the alphabet (A-Z), digits (0-9), minus
> > sign (-), and period (.).
>
> 24 characters? I wonder how much of Germany that leaves out ;-) This RFC
> (1985) must be outdated. RFC822 certainly allows underscores in
> hostnames, so if anyone complains, it should be the name server.
>
> Eric
Here is the relavant section from RFC 1123, I forgot to mention in my
previous append that names longer than 24 characters must be supported.
This does state that RFC 952 obsoletes all previous RFCs, and this is
an ammendment to RFC 952. Please avoid underscores, they aren't legal!
2.1 Host Names and Numbers
The syntax of a legal Internet host name was specified in RFC-952
[DNS:4]. One aspect of host name syntax is hereby changed: the
restriction on the first character is relaxed to allow either a
letter or a digit. Host software MUST support this more liberal
syntax.
Host software MUST handle host names of up to 63 characters and
SHOULD handle host names of up to 255 characters.
Daniel
=====-=====-=====-=====-=====-=====-=====-=====-=====-=====-=====-=====-=====
Daniel M. Barton Internet: dmba...@ralvmm.vnet.ibm.com
TCP/IP Development dmbarton%ral...@vnet.ibm.com
IBM Research Triangle Park, NC USA
Marty Hoag
>>
>Unfortunately, I believe, RFC821 disagrees with RFC822 on this. So what is
>one to do? We have this problem here also: dozens of campus workstations
>have underscores in their names, and FAL's MAKESITE always truncates them.
One of the most frustrating things about trying to set any sorts of
standards when using the RFCs is that each one RFC821, RFC822, RFC1034/1035
have somewhat different definitions of "host name" or whatever. The DNS
folks see their system as a distributed database and thus try to be the
least restrictive.
One needs to look at the "intersection" of the sets of usable domain
names for the various services they want to use. I suppose if
a user wants to use e-mail then "letter-digit-hyphen" describes the
characters in the domain name.
Maybe we need yet another RFC describing "safe" names according to the
various RFCs. Of course the same folks with improper names probably don't
bother checking RFCs anyway... As we say in these parts - Uff da!
Marty