[PHP] Reverse DNS testing
I want to do a rDNS check on a admin entered host name to insure in-coming mail servers don't reject mail, sent by my app, because the rDNS doesn't exist or doesn't match. Here is the fundamental code: $host = $_SERVER['SERVER_NAME']; //site name shared or not $ip = gethostbyname($host); $hostName = gethostbyaddr($ip); //May be different on a shared host $ip2 = gethostbyname($hostName); The $ip works fine. However, one of the shared hosts I'm working with returns this instead of the original $host gethostbyaddr($ip)= 93.247.128.148-static.foo.com [foo is subs for actual] gethostbyname($hostName)= 93.247.128.148-static.foo.com It appears gethostbyname() is just returning $hostName because it is not legit. Using just the foo.com in gethostbyname() returns the host's server IP. Thus, the typical rDNS check fails for this site. Several online checks also report rDNS fails. Any suggestions how I can handle this? -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
Re: [PHP] Reverse DNS testing
On 07/12/2012 11:17 AM, Al wrote:
I want to do a rDNS check on a admin entered host name to insure
in-coming mail servers don't reject mail, sent by my app, because the
rDNS doesn't exist or doesn't match.
Here is the fundamental code:
$host = $_SERVER['SERVER_NAME']; //site name shared or not
$ip = gethostbyname($host);
$hostName = gethostbyaddr($ip); //May be different on a shared host
$ip2 = gethostbyname($hostName);
Throw in a filter_var() check with the FILTER_VALIDATE_IP flag?
if ( filter_var($hostName, FILTER_VALIDATE_IP) === TRUE ) {
# This is an IP
# do something
}
Or do a conditional check
if ( $hostName === $ip2 ) {
# no change...
# handle no resolution issue.
}
The $ip works fine.
However, one of the shared hosts I'm working with returns this instead
of the original $host
gethostbyaddr($ip)= 93.247.128.148-static.foo.com [foo is subs for actual]
gethostbyname($hostName)= 93.247.128.148-static.foo.com It appears
gethostbyname() is just returning $hostName because it is not legit.
Using just the foo.com in gethostbyname() returns the host's server IP.
Thus, the typical rDNS check fails for this site. Several online checks
also report rDNS fails.
Any suggestions how I can handle this?
--
Jim Lucas
http://www.cmsws.com/
http://www.cmsws.com/examples/
http://www.bendsource.com/
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Re: [PHP] Reverse DNS testing
On Jul 12, 2012, at 2:17 PM, Al wrote: I want to do a rDNS check on a admin entered host name to insure in-coming mail servers don't reject mail, sent by my app, because the rDNS doesn't exist or doesn't match. Here is the fundamental code: $host = $_SERVER['SERVER_NAME']; //site name shared or not $ip = gethostbyname($host); $hostName = gethostbyaddr($ip); //May be different on a shared host $ip2 = gethostbyname($hostName); The $ip works fine. However, one of the shared hosts I'm working with returns this instead of the original $host gethostbyaddr($ip)= 93.247.128.148-static.foo.com [foo is subs for actual] gethostbyname($hostName)= 93.247.128.148-static.foo.com It appears gethostbyname() is just returning $hostName because it is not legit. Using just the foo.com in gethostbyname() returns the host's server IP. Thus, the typical rDNS check fails for this site. Several online checks also report rDNS fails. Any suggestions how I can handle this? -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php It appears the RDNS for that ip has not been mapped to the server name do you have control of the DNS servers? can you check the dns config? -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
Re: [PHP] Reverse DNS testing
On 7/12/2012 3:09 PM, Jim Lucas wrote:
On 07/12/2012 11:17 AM, Al wrote:
I want to do a rDNS check on a admin entered host name to insure
in-coming mail servers don't reject mail, sent by my app, because the
rDNS doesn't exist or doesn't match.
Here is the fundamental code:
$host = $_SERVER['SERVER_NAME']; //site name shared or not
$ip = gethostbyname($host);
$hostName = gethostbyaddr($ip); //May be different on a shared host
$ip2 = gethostbyname($hostName);
Throw in a filter_var() check with the FILTER_VALIDATE_IP flag?
if ( filter_var($hostName, FILTER_VALIDATE_IP) === TRUE ) {
# This is an IP
# do something
}
Or do a conditional check
if ( $hostName === $ip2 ) {
# no change...
# handle no resolution issue.
}
The $ip works fine.
However, one of the shared hosts I'm working with returns this instead
of the original $host
gethostbyaddr($ip)= 93.247.128.148-static.foo.com [foo is subs for actual]
gethostbyname($hostName)= 93.247.128.148-static.foo.com It appears
gethostbyname() is just returning $hostName because it is not legit.
Using just the foo.com in gethostbyname() returns the host's server IP.
Thus, the typical rDNS check fails for this site. Several online checks
also report rDNS fails.
Any suggestions how I can handle this?
I have some additional tests already. Left them out of this dialog to just
focus on the essential problem. I check the syntax and stuff before it gets to
this code
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Re: [PHP] Reverse DNS testing
On 7/12/2012 3:58 PM, David OBrien wrote: On Jul 12, 2012, at 2:17 PM, Al wrote: I want to do a rDNS check on a admin entered host name to insure in-coming mail servers don't reject mail, sent by my app, because the rDNS doesn't exist or doesn't match. Here is the fundamental code: $host = $_SERVER['SERVER_NAME']; //site name shared or not $ip = gethostbyname($host); $hostName = gethostbyaddr($ip); //May be different on a shared host $ip2 = gethostbyname($hostName); The $ip works fine. However, one of the shared hosts I'm working with returns this instead of the original $host gethostbyaddr($ip)= 93.247.128.148-static.foo.com [foo is subs for actual] gethostbyname($hostName)= 93.247.128.148-static.foo.com It appears gethostbyname() is just returning $hostName because it is not legit. Using just the foo.com in gethostbyname() returns the host's server IP. Thus, the typical rDNS check fails for this site. Several online checks also report rDNS fails. Any suggestions how I can handle this? -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php It appears the RDNS for that ip has not been mapped to the server name do you have control of the DNS servers? can you check the dns config? Unfortunately, the website is on a typical shared, low cost host. So, I can't get to the DNS record and the outfit's tech support won't help. So, I'm trying to do a reasonable work around in case I run into this issue again on another shared host. -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
