[DRBD-user] Error with numeric hostnames

Philipp Marek philipp.marek at linbit.com
Thu Nov 12 07:05:27 CET 2015

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.

Hi Jeffrey,

> We're using DRBD with heartbeat and we're seeing an error if we configure 
> a host with an all-numeric hostname.
> ---------------------------------
> Starting DRBD resources:
> //etc/drbd.conf:37: Parse error: 'TK_STRING | '('' expected.
> 	but got '123456' (TK 281)
> ---------------------------------
> Line 37 of the drbd.conf file is the "on <host> {" line.  In this case, the hostname being used is "123456".
> This seems like a bug to me, but I haven't found reference to anyone else 
> having the problem, so I thought I'd see if there's a solution that I'm 
> missing.  Seems to me that the parse_hosts() function should accept 

Yeah, right, basically.

The workaround is to enclose the hostname in quotes, as in

    on "123456" {

To be honest, this is the first time I've ever heard of a full-numeric 
hostname; I guess that quite some other things might go wrong this way, 
because IPv4 addresses don't *have* *to* have the dots in them:

    # getent hosts 123456      123456

This is using the inet_pton() function (inet_aton() works the same),
so I don't think we want to support purely numeric hostnames.

If we ever allow to use DNS names in the DRBD configuration files' 
"address" items, should "address 123456:1234" be parsed as IPv4 or via 
host name lookup? Would you risk that your definition "1234567" suddenly 
gets mapped to a 123457.com domain, as soon as someone added that one, 
"just because" your resolv.conf contains "search .com"?

I've seen similar problems with programs that wrote IP addresses via
"%03d.%03d.%03d.%03d" - the leading zeroes make the digits get interpreted 
as octal numbers...

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