whats the frequency of the letter d in:
q: apache: allow from domain without using reverse lookup i want to allow access to a folder from a domain name instead of ip address in apache. now, allow from accepts domains as arguments, but i think it also does a reverse dns lookup to cross check (which is good but too strict for me). is there a way to configure apache not to do the reverse dns check (for that particular allow from directive).
((basically, i want to allow access only from my pc, which has a dynamic ip address. i have mapped it to a domain using dyndns - however the reverse lookup of  my dynamic ip  will not resolve to the domain)).
alternately, if someone can suggest a free service that also configures reverse dns lookup for my dynamic ip (dont know if its possible in first place), that would do the trick as well.
thanks!
jp

a: short answer is no, as apaches allow from must do a reverse and forward dns lookup:
this configuration will cause apache to perform a double reverse dns lookup on the client ip address, regardless of the setting of the hostnamelookups directive. it will do a reverse dns lookup on the ip address to find the associated hostname, and then do a forward lookup on the hostname to assure that it matches the original ip address. only if the forward and reverse dns are consistent and the hostname matches will access be allowed.
my recommendation would be to put some sort of authentication on that particular directory instead of trying to restrict by hostname.

a: update: if you have an apache version >= 2.4.19, you can use
require forward-dns yourhost.example.com

this does not do a reverse lookup. and of course, it then requires full host names. see apaches docs on require forward-dns for details.
for older apache versions:
normally, you cannot use allow from with dynamic hosts (for which the reverse dns generally points to your isp). but i wanted that anyway for some pages which were not worth protecting with authentication. so this is my workaround.
my server is configured to first use the /etc/hosts file before dns. this is done by adding order hosts,bind to /etc/host.conf:
# cat /etc/host.conf 
order hosts,bind
multi on

i have a cron job updating the hosts file every 15 minutes with my current dynamic external ips. in my case, i have my own subdomain on my own dns, and want to update several hosts. the update script i call from cron is:
#!/bin/sh
## update /etc/hosts with our dynamic hosts

# dig ends the domain name with a dot, so we need it
domain=dyn.example.com.

die() {
    echo $1 1>&2
    exit 1;
}

tmpfile=$(mktemp /tmp/hosts.xxxxx)
cp -a /etc/hosts $tmpfile || die cannot copy /etc/hosts to $tmpfile

perl -i -ne print unless /\q$domain\e\s/ $tmpfile || die cannot remove $domain from $tmpfile

dig -t axfr $domain | \
  perl -lne /^(\s+)\s+\d+\s+in\s+a\s+(\s+)/ && print $2 $1 >> $tmpfile \
  || die cannot add $domain entries to $tmpfile

mv $tmpfile /etc/hosts || die error cannot mv $tmpfile to /etc/hosts

if you have a single host to update, your script can be much simpler than that.

user
The passage contains one hundred and eleven "d"s.
assistant