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ip helper-address and xdmcp

Posted on 2003-03-19
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Last Modified: 2013-07-11
Hi,

I've got an Cisco2611xm (2 FastEthernets)

Im running 2 networks:
172.18.0.0/24 (main with alot of x-servers and clients)
192.168.0.0/24 (small with one x-server)

I want to forward xdmcp between the networks so my clients can see everything on the chooser broadcastlist, but im unable to get it to work.

my config
!
interface FastEthernet0/0
 ip address 172.18.0.1 255.255.255.0
 ip helper-address 192.168.60.255
!
interface FastEthernet0/1
 ip address 192.168.60.1 255.255.255.0
 ip helper-address 195.67.24.255
!
ip forward-protocol udp xdmcp

Thanks
0
Comment
Question by:ddlink
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6 Comments
 
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Accepted Solution

by:
epylko earned 1500 total points
ID: 8174918
2 things:

1.  Why is the helper-address on 0/1 pointing to 195.x.x.x?  Shouldn't it point to 172.18.0.255?

2.  Depending on your IOS version, you might have to enable directed broadcasts with "ip directed-broadcast".  That used to be default on older versions of IOS, but due to DoS attacks the default is to turn that off.

-Eric
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Expert Comment

by:epylko
ID: 8174952
And don't forget to turn off the 7 other services that "ip helper-address" turns on by default:

no ip forward-protocol udp tftp
no ip forward-protocol udp domain
no ip forward-protocol udp time
no ip forward-protocol udp netbios-dgm
no ip forward-protocol udp netbios-ns
no ip forward-protocol udp tacacs
no ip forward-protocol udp bootpc
no ip forward-protocol udp bootps
0
 
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Expert Comment

by:epylko
ID: 8175074
And if my first suggestion doesn't work, you might also need: ip forward-protocol any-local-broadcast
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Author Comment

by:ddlink
ID: 8179611
Thanks for your replys. Yes, the 195.x.x.x is wrong. It should point to 172.18.0.255.

IOS version is 12.2.

ip forward-protocol any-local-broadcast is not available.
I get these options:
(config)#ip forward-protocol ?
  nd             Sun's Network Disk protocol
  sdns           Network Security Protocol
  spanning-tree  Use transparent bridging to flood UDP broadcasts
  turbo-flood    Fast flooding of UDP broadcasts
  udp            Packets to a specific UDP port

ip directed-broadcast doesnt do anything.

Unfortunately it still doesn't work. I will install a sniffer on the 0/1 network and see if any broadcast jumps over.
0
 

Author Comment

by:ddlink
ID: 8180112
DOH! Such a lame problem.

I don't know if I should tell this but. I had ZoneAlarm installed on the computer with the X-terminal software, and Zonealarm didn't trust other subnets.

But anyway, your suggestion with: ip directed-broadcast helped!

This is the working config:
!
interface FastEthernet0/0
ip address 172.18.0.1 255.255.255.0
ip helper-address 192.168.60.255
!
interface FastEthernet0/1
ip address 192.168.60.1 255.255.255.0
ip directed-broadcast
!
ip forward-protocol udp xdmcp

Thanks
0
 

Expert Comment

by:steve506
ID: 39318018
I'm working as a tech support agent and this issue was going ahead of my mind! Now i was able to solve it! Thank you so much, guys!
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