• RSS
  • Twitter
  • FaceBook

Welcome to ISAserver.org

Forums | Register | Login | My Profile | Inbox | RSS RSS icon | My Subscription | My Forums | Address Book | Member List | Search | FAQ | Ticket List | Log Out

problems with client IP's ending on .255 ?

Users viewing this topic: none

Logged in as: Guest
  Printable Version
All Forums >> [ISA Server 2004 Firewall] >> General >> problems with client IP's ending on .255 ? Page: [1]
Login
Message << Older Topic   Newer Topic >>
problems with client IP's ending on .255 ? - 28.Sep.2004 12:28:00 PM   
penrose.l@2college.nl

 

Posts: 474
Joined: 29.Jan.2004
From: Netherlands
Status: offline
Anyone experienced any problems with IP addresses ending on .255 ? ( for instance client with IP 192.168.5.255 )
We have trouble with these clients on ISA.
( spoofing errors etc )

Kind regards,
Lex P.
Post #: 1
RE: problems with client IP's ending on .255 ? - 28.Sep.2004 1:15:00 PM   
tshinder

 

Posts: 50013
Joined: 10.Jan.2001
From: Texas
Status: offline
Hi Lex,

Those are illegal host addresses, so it would make sense that the ISA firewall would drop them.

HTH,
Tom

(in reply to penrose.l@2college.nl)
Post #: 2
RE: problems with client IP's ending on .255 ? - 29.Sep.2004 2:18:00 AM   
grinn253

 

Posts: 76
Joined: 12.Jul.2004
From: Seattle
Status: offline
quote:
Originally posted by Lex Penrose:
Anyone experienced any problems with IP addresses ending on .255 ? ( for instance client with IP 192.168.5.255 )

Although we do not have clients that end with .255, I've also noticed that ISA doesn't forward such packets. When client machines are doing their netbios broadcasting to i.e. 192.168.125.255, the ISA logs show traffic isn't passed.

Question: Although ISA didn't pass the (broadcast) traffic (correct behavior), are the remaining client machines on the same subnet still be able to hear the broadcast? Or does the firewall client stop the broadcast at the client?

Thanks!
Edgardo

(in reply to penrose.l@2college.nl)
Post #: 3
RE: problems with client IP's ending on .255 ? - 29.Sep.2004 9:12:00 AM   
tinto

 

Posts: 247
Joined: 9.Sep.2004
From: Italy
Status: offline
quote:
Originally posted by Lex Penrose:
[QB]Anyone experienced any problems with IP addresses ending on .255 ?

they are reserved for broadcast packets, you should not assign such addresses to any machine

(in reply to penrose.l@2college.nl)
Post #: 4
RE: problems with client IP's ending on .255 ? - 29.Sep.2004 9:15:00 AM   
tinto

 

Posts: 247
Joined: 9.Sep.2004
From: Italy
Status: offline
quote:
Although we do not have clients that end with .255, I've also noticed that ISA doesn't forward such packets. Question: Although ISA didn't pass the (broadcast) traffic (correct behavior), are the remaining client machines on the same subnet still be able to hear the broadcast? Or does the firewall client stop the broadcast at the client?

IMO such packets don't pass through the firewall, so the fw cannot stop them [Wink]

(in reply to penrose.l@2college.nl)
Post #: 5
RE: problems with client IP's ending on .255 ? - 6.Oct.2004 3:02:00 PM   
penrose.l@2college.nl

 

Posts: 474
Joined: 29.Jan.2004
From: Netherlands
Status: offline
windows 2003 Enterprise DHCP server by default will assign .255 addresses to clients.
While I know .0 is network ID and .255 is broadcast , the clients with .255 SEEM to work correctly , until they try to cross ISA 2004.

I have made unexisting reservations in DHCP for those clients. However I want to warn ppl that this problem could occur to you and I had a hard time figuring out why the client couldn't connect coz I didn't see the IP ( ping works etc )

Thanks for the replies !
LexP

(in reply to penrose.l@2college.nl)
Post #: 6
RE: problems with client IP's ending on .255 ? - 11.Oct.2004 11:27:00 AM   
sosor

 

Posts: 27
Joined: 16.Jun.2003
From: Denmark
Status: offline
It seems a bit wierd if the ISA Server sees all .255 adresses as broadcast addresses.

What if youre routing a /23 network (ex: 10.192.0.0/23).
Its perfectly legal to use 10.192.0.255 as a client address, while 10.192.1.255 is not.

If ISA Server is not capable of passing traffic to any .255 adresses - I would exclude them in the DHCP scope.

(in reply to penrose.l@2college.nl)
Post #: 7

Page:   [1] << Older Topic    Newer Topic >>
All Forums >> [ISA Server 2004 Firewall] >> General >> problems with client IP's ending on .255 ? Page: [1]
Jump to:

New Messages No New Messages
Hot Topic w/ New Messages Hot Topic w/o New Messages
Locked w/ New Messages Locked w/o New Messages
 Post New Thread
 Reply to Message
 Post New Poll
 Submit Vote
 Delete My Own Post
 Delete My Own Thread
 Rate Posts