[Bug 1479652] Re: [patch] ntpd rejects source UDP ports less than 123 as bogus

[Eric Desrochers]

** Description changed:

  [Impact]
  
  If an NTP client sends a request with a source port less than 123, the
  packet is silently ignored by ntpd. This is occurring in our environment
  due to NAT.
  
  [Test Case]
  
  The problem can easily be reproduced by having an iptable postrouting
  nat forcing the source port to be under 123 set on the client.
+ 
+ Setup:
+ 	==> NTP server = y.y.y.y
+ 	ntp.conf configured to be a server.
+ 	
+ 	==> NTP client = x.x.x.x
+ 	"ntpdate" used to submmit requests
+ 
+         #iptable setup to force src port to be lower than 123
+ 	iptables -t nat -A POSTROUTING -p UDP --dport 123  -j SNAT --to-source 10.55.15.154:100-122
  
  [Regression Potential]
  
  The patch comes from upstream: http://bugs.ntp.org/show_bug.cgi?id=2174
  
  A testfix[1] package has been provided to the community before the SRU
  process to bring more confidence for the patch. Positive feedbacks has
  been given by the community to confirm the patch addressed the bug
  [comment #7]
  
  [1]- https://launchpad.net/~slashd/+archive/ubuntu/bug1479652
  
  [Original description]
  
  [Title copied from Debian bug, which was not filed by me. Description
  below is mine.]
  
  If an NTP client sends a request with a source port less than 123, the
  packet is silently ignored by ntpd. This is occurring in our environment
  due to NAT.
  
  Attached is the patch already accepted upstream which fixes the issue.
  I've verified it fixes the problem. Debian has been ignoring this patch
  for almost 3 years. Can we get this in Ubuntu please?

** Description changed:

  [Impact]
  
  If an NTP client sends a request with a source port less than 123, the
  packet is silently ignored by ntpd. This is occurring in our environment
  due to NAT.
  
  [Test Case]
  
  The problem can easily be reproduced by having an iptable postrouting
  nat forcing the source port to be under 123 set on the client.
  
  Setup:
- 	==> NTP server = y.y.y.y
- 	ntp.conf configured to be a server.
- 	
- 	==> NTP client = x.x.x.x
- 	"ntpdate" used to submmit requests
+  ==> NTP server = y.y.y.y
+  ntp.conf configured to be a server.
  
-         #iptable setup to force src port to be lower than 123
- 	iptables -t nat -A POSTROUTING -p UDP --dport 123  -j SNAT --to-source 10.55.15.154:100-122
+  ==> NTP client = x.x.x.x
+  "ntpdate" used to submmit requests
+ 
+         #iptable setup to force src port to be lower than 123
+  iptables -t nat -A POSTROUTING -p UDP --dport 123  -j SNAT --to-source x.x.x.x:100-122
  
  [Regression Potential]
  
  The patch comes from upstream: http://bugs.ntp.org/show_bug.cgi?id=2174
  
  A testfix[1] package has been provided to the community before the SRU
  process to bring more confidence for the patch. Positive feedbacks has
  been given by the community to confirm the patch addressed the bug
  [comment #7]
  
  [1]- https://launchpad.net/~slashd/+archive/ubuntu/bug1479652
  
  [Original description]
  
  [Title copied from Debian bug, which was not filed by me. Description
  below is mine.]
  
  If an NTP client sends a request with a source port less than 123, the
  packet is silently ignored by ntpd. This is occurring in our environment
  due to NAT.
  
  Attached is the patch already accepted upstream which fixes the issue.
  I've verified it fixes the problem. Debian has been ignoring this patch
  for almost 3 years. Can we get this in Ubuntu please?

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Title:
  [patch] ntpd rejects source UDP ports less than 123 as bogus

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