I cannot install DirectAdmin on my FRESH CentOS 6.0 64bit server without getting installation errors.
Here is what I did straight off the bat:
SSH'd into my NEW server.
Ran the following commands:
[CODE]
yum update -y
yum -y install gcc gcc-c++ flex
wget http://www.directadmin.com/setup.sh
chmod 755 setup.sh
sh setup.sh
[/CODE]

It goes through its prompts:
[CODE]
You now have 2 options for your apache/php setup.
1: customapache: end-of-life software. Apache 1.3, php 4, frontpage. Do not use. No support.
2: custombuild 1.1: newer software (recommended). Apache 2.x, php 4, 5, or both in cli and/or suphp. Defaults to php 5.2
3: custombuild 1.2: simlar to 1.1, newer default versions. Apache 2.x, php 5, 6, or both in cli and/or suphp. Defaults to php 5.3[/CODE]

I selected option 2
It then prompts:
[CODE]Would you like the default settings of apache 2.2 and php 5.2 cli? (y/n):[/CODE]
At first I selected NO and chose to install will CGI and Apache 2.4 but got errors, so I REINSTALLED my server and simply let DirectAdmin do its default setup.
So on this question:
[CODE]Would you like the default settings of apache 2.2 and php 5.2 cli? (y/n):/CODE]
I selected - y
It takes about 5 minutes before I am prompted with this error:
[CODE]
In file included from /usr/include/krb5.h:8,
from /usr/include/openssl/kssl.h:72,
from /usr/include/openssl/ssl.h:165,
from ssl_toolkit_compat.h:33,
from ssl_private.h:60,
from ssl_engine_dh.c:31:
/usr/include/krb5/krb5.h:2601:24: error: et/com_err.h: No such file or directory
In file included from /usr/include/krb5.h:8,
from /usr/include/openssl/kssl.h:72,
from /usr/include/openssl/ssl.h:165,
from ssl_toolkit_compat.h:33,
from ssl_private.h:60,
from ssl_engine_io.c:30:
/usr/include/krb5/krb5.h:2601:24: error: et/com_err.h: No such file or directory
In file included from /usr/include/krb5.h:8,
from /usr/include/openssl/kssl.h:72,
from /usr/include/openssl/ssl.h:165,
from ssl_toolkit_compat.h:33,
from ssl_private.h:60,
from ssl_engine_kernel.c:31:
/usr/include/krb5/krb5.h:2601:24: error: et/com_err.h: No such file or directory
In file included from /usr/include/krb5.h:8,
from /usr/include/openssl/kssl.h:72,
from /usr/include/openssl/ssl.h:165,
from ssl_toolkit_compat.h:33,
from ssl_private.h:60,
from ssl_engine_init.c:29:
/usr/include/krb5/krb5.h:2601:24: error: et/com_err.h: No such file or directory
In file included from /usr/include/krb5.h:8,
from /usr/include/openssl/kssl.h:72,
from /usr/include/openssl/ssl.h:165,
from ssl_toolkit_compat.h:33,
from ssl_private.h:60,
from ssl_engine_config.c:29:
/usr/include/krb5/krb5.h:2601:24: error: et/com_err.h: No such file or directory
In file included from /usr/include/krb5.h:8,
from /usr/include/openssl/kssl.h:72,
from /usr/include/openssl/ssl.h:165,
from ssl_toolkit_compat.h:33,
from ssl_private.h:60,
from mod_ssl.c:27:
/usr/include/krb5/krb5.h:2601:24: error: et/com_err.h: No such file or directory
In file included from /usr/include/krb5.h:8,
from /usr/include/openssl/kssl.h:72,
from /usr/include/openssl/ssl.h:165,
from ssl_toolkit_compat.h:33,
from ssl_private.h:60,
from ssl_engine_mutex.c:31:
/usr/include/krb5/krb5.h:2601:24: error: et/com_err.h: No such file or directory
In file included from /usr/include/krb5.h:8,
from /usr/include/openssl/kssl.h:72,
from /usr/include/openssl/ssl.h:165,
from ssl_toolkit_compat.h:33,
from ssl_private.h:60,
from ssl_engine_log.c:30:
/usr/include/krb5/krb5.h:2601:24: error: et/com_err.h: No such file or directory
make[3]: *** [ssl_engine_dh.lo] Error 1
make[3]: *** Waiting for unfinished jobs....
make[3]: *** [ssl_engine_mutex.lo] Error 1
make[3]: *** [ssl_engine_io.lo] Error 1
make[3]: *** [ssl_engine_log.lo] Error 1
make[3]: *** [ssl_engine_init.lo] Error 1
make[3]: *** [ssl_engine_kernel.lo] Error 1
make[3]: *** [mod_ssl.lo] Error 1
make[3]: *** [ssl_engine_config.lo] Error 1
make[3]: Leaving directory `/usr/local/directadmin/custombuild/httpd-2.2.22/modules/ssl'
make[2]: *** [all-recursive] Error 1
make[2]: Leaving directory `/usr/local/directadmin/custombuild/httpd-2.2.22/modules/ssl'
make[1]: *** [all-recursive] Error 1
make[1]: Leaving directory `/usr/local/directadmin/custombuild/httpd-2.2.22/modules'
make: *** [all-recursive] Error 1
*******************************************
*******************************************

Cannot find /usr/local/bin/php
Please recompile php with custombuild, eg:
cd /usr/local/directadmin/custombuild
./build all d

This appears to be a 64-bit system.
a common cause of http/php compile failures is mentioned here:
http://help.directadmin.com/item.php?id=213

If you're running CentOS (not freebsd or debian) and applies to you, then type:

ln -sf /usr/lib64/libexpat.so /usr/lib/libexpat.so
ln -sf /usr/lib64/libm.so /usr/lib/libm.so
ln -sf /usr/lib64/libssl.so /usr/lib/libssl.so
cd /usr/local/directadmin/custombuild
./build all d

*******************************************
*******************************************
[/CODE]

I really would like to use DirectAdmin again as I pay for it and use it on all my servers.
DirectAdmin works when I install it on the same server with CentOS 5.8 just not with 6.0 :\