LDAP Setup on linux for Zimbra

harshgrover
harshgrover used Ask the Experts™
on
okie, so i am a newbie on Linux.

I have two servers that i am configuring. Both the servers are in different networks for now, i.e., they are being hosted by different vendors

Server 1:
    DNS server, the domain name is configured for its IP. Has a few opensource applications like mysql etall running on it. Currently, our mail also runs out of that box. We are using sendmail.

Server 2:
    I am trying to install Zimbra on this server, but LDAP authentication keeps on failing. I checked server 1, and the LDAP port (389) is disabled. what do i need to  do, to get the ldap authentication working, and also open up the port 389 on server1?

Server1 is running on Linux enterprise
Server2 is running on CentOS

Just to add a note to this peculiar setup, i am trying to phase out server1. I would get a second new server with the new vendor, but i wanted the mail to be up and running before i phase out the 1st server.


Thanks,
Gary.
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Kerem ERSOYPresident

Commented:
hi,

Is LDAP port active when you querried the Server 2? If it is that wthis may be a problem with the default Firewall which is built over Centos.

Author

Commented:
yep...the port for LDAP is active on server2, however, its closed on server 1
President
Commented:
Ok, then it means that your firewall is blocking the address.

As a quick fix. Go to the teminal in server2 and type this command:

iptables -F RH-Firewall-1-INPUT

and then:

iptables -L

it must disply something similar to that:

Chain INPUT (policy ACCEPT)
target     prot opt source               destination        
RH-Firewall-1-INPUT  all  --  anywhere             anywhere            

Chain FORWARD (policy ACCEPT)
target     prot opt source               destination        
RH-Firewall-1-INPUT  all  --  anywhere             anywhere            

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination        

Chain RH-Firewall-1-INPUT (2 references)
target     prot opt source               destination

edit /etc/sysconfig/iptables:

add this line :
-A RH-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp --dport 389 -j ACCEPT

just before:

-A RH-Firewall-1-INPUT -j REJECT --reject-with icmp-host-prohibited
COMMIT

save and exit. issue these commands:

service iptables restart



Kerem ERSOYPresident

Commented:
now your firewall allows LDAP traffic.

And the quickfix in the beginning just disables the firewall altogether! This is ok for tests but then ad thenecessary rule and restart as I indicated on the following  example.

Cheers,
K.

Author

Commented:
hey Kerem,
    Thanks for the update :). I'll have to wait till the evening to try this out though. i dont have access to the remote servers from work :)...
Kerem ERSOYPresident

Commented:
:) usually I'd expect the opposite but OK :)

Author

Commented:
hehe...i know...this is wierd...but this is not for work ;)...this is some gig that i am working on :)

Author

Commented:
hey Bro,
    i modified the iptables on my domain, but i still dont see 389 to be open.

    i did a nmap and it still does not show up in the list of open ports. do i need to reboot the system?

Thanks,
Gary

Author

Commented:
increasing the points to 250 :(

Author

Commented:
just to clarify the configuration again.


Server1: Enterprise Linux

Server2: CentOS

Install of zimbra: being done on Server2.

server2 tries to connect to server1 for LDAP.

LDAP port is open on server2, but it does not show up as an open port on server1 (Linux) when i do Nmap on the same.

not really sure what's going wrong here.
Kerem ERSOYPresident

Commented:
Hi,

in fact last time I'verespondedn you, I had thought that you were accessing the ldap port from the CentOS system via telnet localhost 389, but you were not able to reach it from the lold redhat system telnet <centos_IP> 389. Is it really the case ?

or you can not access to LDAP system from neither CentOS or Old RHEL ? Please Log-on to the centos system. type:
netstat -anpt | grep :389

Post the output here. Please Also sendme the output of the command:
iptables -L
 

Author

Commented:
ah...i guess i was not really clear on the issue then :(...

LDAP starts on the centOS system, and works fine. however, its not initialized on the Linux enterprise server. when i do nmap, i dont see port 389 open on the linux enterprise server. i want to open the ldap port on the linux server
nociSoftware Engineer
Distinguished Expert 2018

Commented:
Is the slapd process actualy started on the RHEL server?
'ps ax | grep slapd'

if so, what does 'netstat -antp | grep slapd' show?
it might be port 389 ( would seem strange wrt to the above answers)
it might be port 636 ( which actualy is ldaps )
Also note the addresses it listens on (127.0.0.1 or 0.0.0.0 or different)

if not, what stopped it (grep slapd /var/log/*[a-y] )

in the second case you need to:
either modify the config on the CentOS server to use the secured line (prefered)
or modify the RHEL server to not use ldaps.. (not advised).

There is no immediate need for an ldap server on the CentOS system, unless you mean to move the data from the one to the other. (can also be done through slapcat,
slapadd and friends)
Or you can configure them to be mirros of each other.

Kerem ERSOYPresident

Commented:
Noci,

I guss yrr mising the point. The initial question specifies that LDAP is available when connected locally on the CentOS system but not reachable from a remote system.

I guess this rather a problem ie either related to Firewall configuration or LDAP bound to localhost only.
nociSoftware Engineer
Distinguished Expert 2018

Commented:
KeremE,

In the description of server2 (CentOS) is stated it can't reach ldap on server1..?
Otherwise there is (AFAICT from the question) hardly any need to configure LDAP in
all tools of a server that is going to be phased out.

Also there can be a problem in between like a firewall, NAT gateway etc.
that block traffic (the systems are on different networks).
Plain LDAP over a hostile networks is not advised.

Get the tcptraceroute tool and check if there is a block in between:
http://michael.toren.net/code/tcptraceroute/
 with 'tcptraceroute server1 398 '
      'tcptraceroute server1 636 '
from server2 and vice versa.


Kerem ERSOYPresident

Commented:
Noci,

I asked:
hi,

Is LDAP port active when you querried the Server 2? If it is that wthis may be a problem with the default Firewall which is built over Centos.
 
I got this response from the author:
yep...the port for LDAP is active on server2, however, its closed on server 1
Kerem ERSOYPresident

Commented:
Also he said this:

> LDAP port is open on server2, but it does not show up as an open port on server1 (Linux) when i do Nmap on the same.

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