Forum Discussion
adiezma_1656
Nimbostratus
NimbostratusiRule for LDAP Master or Slave
Hi,- If the F5 receives read requests are redirected to the ldap farm slaves.- If the F5 receives write requests are redirected to the master ldap farm.Can this be done with iRules?Antonio.
I need a iRule for LDAP. What you have to do is the following:
11 Replies
- nitass
Employee
is this applicable?
ldap proxy
http://devcentral.f5.com/wiki/iRules.LDAPProxy.ashx 
adiezma_1656This rule may be worth me. What I see is where I have to define my pool's LDAP read and write. I do not know where to put it.- nitassI do not know where to put it.it is readPool and writePool variable in RULE_INIT.
- adiezma_1656It gives me an error:
can not read ":: ldap_writes": no such variable while executing "$ msgtype matchclass equals $:: ldap_writes - adiezma_1656I think I still need to get this:
class ldap_writes {
6
8
10
12
}
I do not know where put it. Fails in iRules - nitasscan not read ":: ldap_writes": no such variable while executing "$ msgtype matchclass equals $:: ldap_writes is there a space between $ and msgtype and between $:: and ldap_writes? $msgtype and $::ldap_writes is one word (no space).
by the way, if you are using 9.4.4+, $:: prefix is no longer required. so, you can remove it.
from:
matchclass $msgtype equals $::ldap_writes
to:
matchclass $msgtype equals ldap_writes
CMP Compatibility
http://devcentral.f5.com/wiki/iRules.CMPCompatibility.ashx?From=iRules.CMP
I do not know where put it.it is called data group in webui. it is at local traffic > irules > data group list. - If you haven't added the data group yet, that will most certainly fail. If you need help on adding a data group let us know, but it should be pretty straight-forward. It's under iRules in the UI, as nitass said.
Colin - adiezma_1656Hi,
My version is 10.2.1.
Now my iRule is this:
when RULE_INIT {
Read Pool
set static::readPool mypool_slave
Write Pool
set static::writePool mypool_master
Turn on debugging
set static::ldap_debug 0
A lookup table for debugging
array set static::msg_types {
0 "bind request"
1 "bind response"
2 "unbind request"
3 "search request"
4 "search response"
6 "modify request"
7 "modify response"
8 "add request"
9 "add response"
10 "delete request"
11 "delete response"
12 "modifydn request"
13 "modifydn response"
14 "compare request"
15 "compare response"
16 "abandon request"
23 "extended request"
24 "extended response"
}
}
when CLIENT_ACCEPTED {
set rebind 0
set binding ""
set replayop ""
set writing 0
TCP::collect
}
when CLIENT_DATA {
Grab the current payload collected
set payload [TCP::payload]
Pull the first 2 bytes.
binary scan $payload H2c ber_t ber_len
The first byte is the tag signifying an LDAP message,
Always is hex 30, if that is not so reject
if { $ber_t ne "30" } {
reject
return
}
The second byte is one of two values:
a) The length of the packet minus the above
defining byte and the length byte
OR
b) an octet describing how many subsequent bytes
hold the packet length
In either case the message type (what we are after)
follows the message id field which too can be a variable
number of bytes.
set len_bytes 0
if { [expr [expr ($ber_len + 0x100) % 0x100] & 128] > 0 } {
set len_bytes [expr [expr ($ber_len + 0x100) % 0x100] & 127]
}
How many bytes is the message id
binary scan $payload x[expr 3 + $len_bytes]c msgid_bytes
The message type is then 4 bytes + number length bytes + number of
message id bytes offset.
binary scan $payload x[expr 4 + $len_bytes + $msgid_bytes]c msgtype
msgtype - BER encoded value, bits 1-5 are the actual
type, 6 is the data type, 7-8 are the data class
Here we only care about the lower 5 bits
set msgtype [expr $msgtype & 31]
if {$static::ldap_debug and
[catch {
log local0. "message type is: $static::msg_types($msgtype) $msgtype"
}
]
} {
log local0. "Bad message type: $msgtype"
reject
}
Each connection should start with a bind request
We'll save this packet for later rebinding when we
flip between servers
if { $msgtype == 0 } {
if {$static::ldap_debug} {log local0. "Bind Request with: ldap_read"}
set writing 0
set rebind 0
set binding $payload
LB::detach
pool $static::readPool
If we come across a write request and are currently not
sending data to the write pool, detach, and set the rebind
flag so we can send the bind packet before we actually send
our write request
} elseif {[matchclass $msgtype equals $::ldap_writes] and $writing != 1} {
if {$static::ldap_debug} {log local0. "Rebinding with: ldap_write"}
set rebind 1
set writing 1
set replayop $payload
TCP::payload replace 0 [TCP::payload length] $binding
LB::detach
pool $static::writePool
If we come across a read request while we are bound to a write server
we need to detach and rebind with a read server from the read pool
} elseif {![matchclass $msgtype equals $::ldap_writes] and $writing == 1} {
if {$static::ldap_debug} {log local0. "Rebinding with: ldap_read"}
set rebind 1
set writing 0
set replayop $payload
TCP::payload replace 0 [TCP::payload length] $binding
LB::detach
pool $static::readPool
}
TCP::release
TCP::collect
}
when SERVER_CONNECTED {
A change in the type of request has been detected
requiring a rebind, we've sent the bind now we need to
wait for the response before we send the actual request
if { $rebind == 1 } {
TCP::collect
}
}
when SERVER_DATA {
if { $rebind == 1 } {
set rebind 0
See above for details on this block. Stupid iRules, no proc grrrr
set payload [TCP::payload]
Pull the first 2 bytes.
binary scan $payload H2c ber_t ber_len
set len_bytes 0
if { [expr [expr ($ber_len + 0x100) % 0x100] & 128] > 0 } {
set len_bytes [expr [expr ($ber_len + 0x100) % 0x100] & 127]
}
binary scan $payload x[expr 3 + $len_bytes]c msgid_bytes
binary scan $payload x[expr 4 + $len_bytes + $msgid_bytes]c msgtype
set msgtype [expr $msgtype & 31]
If the msgtype we have here is for a bind response just discard
it as we don't need to send it to the client
if {$msgtype == 1 } {
TCP::payload replace 0 [TCP::payload length] ""
}
Now send the actual read or write op to the server
It should now have processed the bind
TCP::respond $replayop
}
TCP::release
}
it's correctly?
I am not accustomed to using rules. I do not know that I have to do to configure this:
class ldap_writes {
6
8
10
12
}
how?, why? this is crazy!! aahhhhh
hahaha
Sorry, Antonio. 
xushu_120868Hi,
I read your I irules and I need an irules that
If theF5receivesrequestsfrom users belong to different "DC"s, F5 need to send them to different pool.how can I change this rule.Thank you very much .- nitassIf the F5 receives requests from users belong to different "DC"show do you determine if user is from local or another dc?
