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## 5. The magic time

In this section will be discused all the problems that you have and the changes that you propose to the installation. Please feel free to email me and ask about any difficult or not mentioned points in this document. My email is cs98011@icsd.aegean.gr

Q: A DHCP is already running. How do I configure BOOTP, so as no interaction is made with the DHCP?

A: This was the main problem I faced when I installed the system on a running network. DHCP and BOOTP use the same port. When a windows client boots, it issues a DHCP/BOOTP request to locate its IP (of course in case of dynamic IP). When the DHCP server responds, it also returns the IP's of DNS servers, print servers and Domain Controlers. My BOOTP server was responding faster than the Microsoft DHCP server, an so Windows clients were unable to locate their Domain controler. This resulted to users not being able to login! The solution described here was donated by D. Spinellis.

Open the `/usr/src/linux/net/ipv4` file. This is were all BOOTP autoconfiguration is done. Search for `udph.source`,`udph.dest` variables. You will see that they are set to the standard 67/68 request/responce ports. Change BOTH values so they use an unused UDP port in your network. A good port pair that no application uses it is 967/968. Now, start your DHCPd with the -p 967 option. Everything must be working OK!

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