topic Re: HOSTNAME/LENGTH in Operating System - HP-UX

HOSTNAME/LENGTH

Nobody's Hero — Tue, 13 Aug 2002 14:10:42 GMT

Can someone tell me what the max limit is for a UNIX hostname and where that is defined?

Thanks,
RPM

Re: HOSTNAME/LENGTH

Jeff Schussele — Tue, 13 Aug 2002 14:14:11 GMT

Hi Robert,

Although the max length for an HP hostname is 64 chars, due to the limitations of UUCP & the uname command, it's STRONGLY recommended to keep it <= 8.

The hostname length is not defined in a config file anywhere that I'm aware of other than being hardcoded in a library somewhere.

Rgds,
Jeff

Re: HOSTNAME/LENGTH

Pete Randall — Tue, 13 Aug 2002 14:15:14 GMT

Though you can have longer, 8 characters is the realistic limit. You invite all kinds of problems exceeding 8.

Pete

Re: HOSTNAME/LENGTH

James R. Ferguson — Tue, 13 Aug 2002 14:15:39 GMT

Hi Robert:

'hostname' and 'uname' should be the same and therefore cannot exceed 8-characters. The length of the 'uname' structure is defined in '/usr/include/sys/utsname.h'in '_SYS_NMLN' (see man 2 'uname'). Since this is a 9-character, null-terminated string, the maximum, safe, hostname size is eight (8).

Regards!

...JRF...

Re: HOSTNAME/LENGTH

Victor_5 — Tue, 13 Aug 2002 14:15:53 GMT

Generally, it is <=8.

Re: HOSTNAME/LENGTH

Pete Randall — Tue, 13 Aug 2002 14:18:37 GMT

Re: HOSTNAME/LENGTH

Sridhar Bhaskarla — Tue, 13 Aug 2002 14:20:51 GMT

Hi,

The max limit for nodename (uname -n) length is 8 which is UTSLEN -1 as defined in utsname.h. It is recommended to set hostname equal to nodename.

-Sri

Re: HOSTNAME/LENGTH

S.K. Chan — Tue, 13 Aug 2002 14:21:06 GMT

You already got the answer for it's max limit from the rest. it's defined in /usr/include/sys/utsname.h.
# cd /usr/include/sys
# grep SYS_NMLN utsname.h
Look for the string that says "define _SYS_NMLN"

Re: HOSTNAME/LENGTH

Sajid_1 — Tue, 13 Aug 2002 14:21:56 GMT

hello,

The answer for your question can be found from:
# man hostname
The max. limit will be defined in /usr/include/sys/param.h with the parameter - MAXHOSTNAMELEN. This is 64.

However, It is strongly recommended to keep your hostname up to 8 characters. Because the UUCP nodename is restricted to 8 characters and it automatically accepts the value from the set hostname.

Re: HOSTNAME/LENGTH

Sajid_1 — Tue, 13 Aug 2002 14:23:47 GMT

hello,

Read this document for more information about hostname set more than 8 characters:
http://support2.itrc.hp.com/service/cki/docDisplay.do?docLocale=en_US&docId=200000046860426

Doc ID - S3100000646

Re: HOSTNAME/LENGTH

Bill Hassell — Tue, 13 Aug 2002 14:57:18 GMT

The recommendations about hostname are valid. And you can indeed change the UUCP name by setting the variable: NODENAME= which is poorly documented (see /sbin/init.d/hostname). Usually, requests for long hostnames comes from a corporate naming convention.

However, there is a solution for both requirements: make HOSTNAME=NODENAME= and then create an alias in DNS (or /hosts) for the longer name. Now your machine can be known as:

max8char and also: nomax8chars4mymachine

Internal to HP-UX, the utilities will be happy with the 8char limit and externally, users can find your machine with the long name or the short name.