Can lpd be configured not to do reverse DNS

[dirt]

I have an AIX print server configured to allow anyone to print to it. The hosts.lpd file contains a "+" entry. Despite this, the lpd daemon insists on doing a reverse DNS lookup to get a hostname. This causes problems with PC's using DHCP because reverse DNS is not very reliable on these.

Is it possible to configure lpd to not do reverse DNS and allow printing?

 

[Guest_imported]

i use

/etc/netsvc.conf
hosts=local

it uses /etc/hosts for gethostby* (like lpd does)
and gives nameserver address to sendmail, squid , .... who use more sophisticated resolvers

or use hosts=local,bind to get more popular resolver config which is not default in AIX ( it uses only BIND )...

 

[Yegolev]

My qdaemon does dns lookup on a supplied hostname, unless there is an entry in /etc/hosts, but what you are saying is that you are supplying an IP to your queue and it is looking up the name? I'm curious how you do this. Or maybe I misunderstand. IBM Certified -- AIX 4.3 Obfuscation

 

[dirt]

The problem that occurs is this:

1) A PC or laptop requests an IP address through DHCP when the user logs in first thing in the morning. It gets a randomly chosen IP address that the nameservers don't have a hostname associated with yet. The DHCP server sends this information to the dyanmic DNS nameserver system.

2) For some reason, dynamic DNS nameserver does not get IP to hostname mapping for the PC in question. i.e. if you do reverse DNS on the IP address obtained, the namserver responds "not found".

3) The PC user prints to AIX printserver.

4) The AIX lpd daemon receives a print job from PC. All it knows is IP address of the originating PC. It attempts to do a reverse DNS to get the hostname of the originating machine. Since the nameserve isn't in sync with the DHCP server, the reverse DNS lookup fails. The AIX lpd daemon refuses the request.

Since this printserver is set up to receive jobs from any machine, I'd like to have it not check the originating IP address. I've set up the "+" entry in /etc/hosts.lpd, but it still rejects the job if reverse DNS fails. I'd like to be able to configure the lpd daemon to not do reverse DNS at all, just accept the print request.

Part of the problem is that this works most of the time. If the DHCP to nameserver communication worked all the time, we would be OK. The current situation is that it frequently fails and DHCP PC users can't print. The problem would actually be worse, but the most common scenario is that the nameserver is far behind the DHCP server, and when a reverse DNS request comes in, the nameserver returns a hostname that was using the IP address in question earlier. Even though the hostname is incorrect, this satisfies the lpd daemon and the print job runs.

It seems that this can't be a unique problem and the there "should" be a way to configure lpd not to fail if reverse DNS fails.

The "real" problem is in the network infrastructure. I would like to see if we can work around this by configuring the AIX print server differently to ignore the problem.

The "ideal" solution would be to keep the dynamic DNS/DHCP stuff working right all the time, but, in the meantime, it would be a big service to the users to make printing work without depending on the dynamic DNS working.

 

[dirt]

The problem that occurs is this:

1) A PC or laptop requests an IP address through DHCP when the user logs in first thing in the morning. It gets a randomly chosen IP address that the nameservers don't have a hostname associated with yet. The DHCP server sends this information to the dyanmic DNS nameserver system.

2) For some reason, dynamic DNS nameserver does not get IP to hostname mapping for the PC in question. i.e. if you do reverse DNS on the IP address obtained, the namserver responds "not found".

3) The PC user prints to AIX printserver.

4) The AIX lpd daemon receives a print job from PC. All it knows is IP address of the originating PC. It attempts to do a reverse DNS to get the hostname of the originating machine. Since the nameserve isn't in sync with the DHCP server, the reverse DNS lookup fails. The AIX lpd daemon refuses the request.

Since this printserver is set up to receive jobs from any machine, I'd like to have it not check the originating IP address. I've set up the "+" entry in /etc/hosts.lpd, but it still rejects the job if reverse DNS fails. I'd like to be able to configure the lpd daemon to not do reverse DNS at all, just accept the print request.

Part of the problem is that this works most of the time. If the DHCP to nameserver communication worked all the time, we would be OK. The current situation is that it frequently fails and DHCP PC users can't print. The problem would actually be worse, but the most common scenario is that the nameserver is far behind the DHCP server, and when a reverse DNS request comes in, the nameserver returns a hostname that was using the IP address in question earlier. Even though the hostname is incorrect, this satisfies the lpd daemon and the print job runs.

It seems that this can't be a unique problem and the there "should" be a way to configure lpd not to fail if reverse DNS fails.

The "real" problem is in the network infrastructure. I would like to see if we can work around this by configuring the AIX print server differently to ignore the problem.

The "ideal" solution would be to keep the dynamic DNS/DHCP stuff working right all the time, but, in the meantime, it would be a big service to the users to make printing work without depending on the dynamic DNS working.

 

[dirt]

Does anyone have any ideas on how to make lpd daemon stil print if reverse DNS fails? Or any suggestion on the workaround?

 

[Yegolev]

No idea about a workaround. Personally I would use this as a big club to beat the network team over the head until it was fixed. Unless you are also the network team. =)

We use JetDirect so I am useless here. IBM Certified -- AIX 4.3 Obfuscation