Can't ftp to server after new of DNS

[Anders Dahlgren]

Hi,

We recently replaced our DNS-server and updated /etc/resolv.conf. After the change it's no longer possible to ftp to the server. If we add the client to the hosts file it fill work. Both the server and clients has entrys in the DNS, both A- and PTR-records.

From syslog after a connection attempt:
Nov 4 11:22:17 server inetd[6819]: ftp/tcp: Connection from unknown (x.x.x.x) at Fri Nov 4 11:22:17 2005
Nov 4 11:22:17 server ftpd[6819]: getpeername (ftpd): Invalid argument
Nov 4 11:22:17 server inetd[6820]: registrar/tcp: Connection from server (y.y.y.y) at Fri Nov 4 11:22:17 2005

Any suggestion what we've done wrong?
Best regards
/Anders

[Arunvijai_4]

Can you able to ping from your client to server ? You may need to update your routing table.

-Arun

[Anders Dahlgren]

Yes, I can ping.

It's a name resolution problem. If I add the client to /etc/hosts file it works and I get connected.

It worked with our old DNS-server. As far as I know the only thing that has changed is the DNS and the config in /etc/resolv.conf.

[Steven E. Protter]

There is probably a problem with the dns record.

testtools

dig
nslookup

host

These command may show you a DNS problem which needs correction.

Otherwise /etc/resolv.conf is the suspect.

SEP

[Arunvijai_4]

# nslookup What does it give ?

I think, you have problem with DNS entries.

-Arun

[Muthukumar_5]

Hope this is the problem with resolvation.

Start check as,

# /etc/nsswitch.conf
hosts: entries

# /etc/hosts -- files
# /etc/resolv.conf -- dns

Post this information as,

# nsquery hosts "files"
# nsquery hosts "files"
# nsquery hosts "dns"
# nsquery hosts "dns"

It will answer your question. May be DNS is not having reverse resolvation record for your hostname.

-Muthu

[Ivan Ferreira]

It seems that you server cannot resolve the names. Is there a firewall between the server and the DNS server?

Maybe you need to update your firewall rules to allow the FTP server access to the DNS server.

Also, in your DNS server, verify that an allow-query option is not preventing the FTP server to query it.

[Sameer_Nirmal]

Hi,
I guess with the new DNS server , there might be in changes with domain naming convention which will affect the host in the domain ( fully qualified host name in domain ). Verify if there is domain mis-match or changes and ensure you have appropriate changes in the /etc/resolv.conf

When you put the full name of your DNS server in the /etc/hosts file, the resolution would work as it
name-ip resolution is done locally and ftp would the IP address directly for the remote host.

Now when you are trying to use resolver for remote DNS , the resolver query is returned with unresolved query from the DNS. The ftpd is showing that error because it can't get the IP address of the host ( whoes name is supposed to be resolved by the DNS server )

So there may be problem at the DNS server side . Saying that the client configuration is not correct or it is not added at all.

Verify the db.domain and db.net files at DNS server side.