JEFF@MITVMA.MIT.EDU (Jeff Harrington) (03/01/91)
Hi,
I've been getting complaints about my SMTP rejecting mail from sites
with a underscore in its host name. If I read RFC 821 correctly, names
may consist of letters, digits, and hyphens. Has this been liberalized
recently?
The site in question is: its_gate.cc.uow.edu.au
Thanks,
Jeffdmbarton@ralvmm.vnet.ibm.com ("Daniel M. Barton") (03/03/91)
> Hi, > I've been getting complaints about my SMTP rejecting mail from sites > with a underscore in its host name. If I read RFC 821 correctly, names > may consist of letters, digits, and hyphens. Has this been liberalized > recently? > The site in question is: its_gate.cc.uow.edu.au > > Thanks, > Jeff RFC 821 and 822 weren't very clear on what characters a hostname could contain. RFC 952, "DOD Internet Host Table Specification" clarifies what characters are legal. The legal characters are letters, numbers, and the hyphen, and the hostname must begin with a letter, and end with a letter or digit. The exact syntax is: <hname> ::= <name>*("."<name>) <name> ::= <let>(*(let-or-digit-or-hyphen>)<let-or-digit>> Note: I used parentheses instead of square brackets (none on my terminal...) Daniel ======================================================================== Daniel M. Barton TCP/IP Development IBM Research Triangle Park, NC Internet: dmbarton@ralvmm.vnet.ibm.com dmbarton%ralvmm@vnet.ibm.com
braden@ISI.EDU (03/03/91)
RFC-1123 (Section 2.1) points you to RFC-952, and then liberalizes the syntax to allow "3COM.COM". Bob Braden
emv@ox.com (Ed Vielmetti) (03/03/91)
underscores are found in some hostnames managed by merit on behalf of the nsfnet, e.g. ann_arbor.mi.nss.nsf.net, 129.140.17.77. until these names are changed, it's hard to argue that underscores are illegal, just ill-advised. --Ed emv@ox.com please ignore the goofy From: line in the header.
VANCE@TGV.COM (Icarus) (03/04/91)
>underscores are found in some hostnames managed by merit on behalf of >the nsfnet, e.g. ann_arbor.mi.nss.nsf.net, 129.140.17.77. until these >names are changed, it's hard to argue that underscores are illegal, >just ill-advised. Doing something in broad daylight doesn't make it legal. If we want to expand the allowable characters in host names (which I think is quite reasonable), then let's move on that. RFC 1123 (Host Requirements) explicitly relaxes the restriction of the first character in a host/domain name being a letter (now allows numbers as well), but it does NOT add an underscore to the valid set of characters. Until a change is "officially" made, using underscores in hostnames is a mistake, and can cause problems for some hosts. Regards, -----Stuart
08071TCP@MSU.BITNET (Doug Nelson) (03/08/91)
>underscores are found in some hostnames managed by merit on behalf of >the nsfnet, e.g. ann_arbor.mi.nss.nsf.net, 129.140.17.77. until these >names are changed, it's hard to argue that underscores are illegal, >just ill-advised. Ed, the existence of a counter-example is a wonderful way to disprove theory, but hardly the way to invalidate an RFC.... Just because Merit uses such names doesn't make them legal. Doug Nelson Michigan State University