Firewall Port settings for DHCP 1

[rpg121]

What port does DHCP use to resolve ip addresses, subnets and gateway info? I set up my firewall and clients can't get DHCP info while its up, but can when its down. Thanks

 

[crazynoodle]

DHCP is based on bootp packets and is a broadcast and does not use ports. If your DHCP Server is on the same segment as your clients then I can't see any reason that the Firewall would interfere with DHCP.

If by chance your DHCP Server is remote and your using your router to forward these requests (by changing the request to a unicast - DHCP Relay-Agent) You may be blocking all IP access to this Server.

Really need more info though.

~CN~

 

[rpg121]

The server is local. The firewall I'm using is BlackICE. I'm just using the normal DHCP service and internet connection sharing. The clients can only detect the DHCP settings and server if the firewall is down.

If the firewall is up, they turn to the automated ip addresses, and to fix that I have to disable the firewall and renew the ip address using ipconfig.

Hope that's enough info.

Thanks

 

[crazynoodle]

Is the DHCP service on the same physical Server that has BlackIce installed? If so - when the FW is operational and you send a DHCP Request to the server - does this trigger any events in the FW Log?

 

[rpg121]

It is on the same physical server and it leaves no log entry.

 

[ashpp]

Is there any point in firewalling your internal ethernet connection?

 

[justcurious]

According to Internet Security Systems, DHCP actually does use port 67. Try adding a rule for that port in your Advanced Firewall settings.

See this article:

https://iss.custhelp.com/cgi-bin/is...X5hbnl_JnBfc29ydF9ieT1kZmx0JnBfcGFnZT0x&p_li=