Cisco Systems PIX 515 doesn't route packets

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Subject Author Date
PIX 515 doesn't route packets "B Squared" 07-19-05
Posted by on July 19, 2005, 5:58 pm
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The following is the configuration file for my PIX 515.
For some reason I can no longer get any http packets to cross
between the interfaces. This change first occurred when
I turned off the fixup protocol for http, and then turned
it back on. I posted a question about this about a week
ago, but the concensus was that the fixup protocol issue
probably wasn't the real problem.

If this were a normal router, not a PIX, from the
behavior I'd say it's either 1) A bad access list, or
2) the network statements haven't been entered correctly
and the thing isn't routing. But the access list looks
sufficently general to let http pass.

For testing I always enter the IP address in decimal, not
a web address so that DNS doesn't cloud the issue.

By using the packet debug command I can see the packets
at the outside interface whenever I point the browser
at the web server in the dmz, but no packets ever come
out of the dmz interface. This used to work just fine.
I'm stumped!

I've inserted some comments along the way to aid the
discussion.

------------------------------------------

PIX Version 6.3(4)
! this is all pretty normal

interface ethernet0 auto
interface ethernet1 auto
interface ethernet2 auto
nameif ethernet0 outside security0
nameif ethernet1 inside security100
nameif ethernet2 dmz security50

! naming stuff
hostname pixfirewall
domain-name our_domain_name.net

! the normal fixups, but I've turned ftp off
fixup protocol dns
no fixup protocol ftp 21
fixup protocol h323 h225 1720
fixup protocol h323 ras 1718-1719
fixup protocol http 80
fixup protocol rsh 514
fixup protocol rtsp 554
fixup protocol sip 5060
fixup protocol sip udp 5060
fixup protocol skinny 2000
fixup protocol smtp 25
fixup protocol sqlnet 1521
fixup protocol tftp 69

names

! for my basic testing I attempt to permit http and https
! in a very general way

access-list web permit tcp any any eq www
access-list web permit tcp any any eq https
access-list web permit ip any any


! these are pretty much by the book
pager lines 24
mtu outside 1500
mtu inside 1500
mtu dmz 1500

! my addresses, as expected

ip address outside xxx.xxx.xxx.xxx 255.255.255.224
ip address inside xxx.xxx.xxx.xxx 255.255.255.0
ip address dmz xxx.xxx.xxx.xxx 255.255.255.224

ip audit info action alarm
ip audit attack action alarm

! the pdm wasn't all the useful. it tells me I'm not
! getting any packets across the interfaces, which I knew

pdm location xxx.xxx.xxx.xxx 255.255.255.255 inside
pdm location xxx.xxx.xxx.xxx 255.255.0.0 outside
pdm history enable
arp timeout 14400

! use the inside and dmz addresses without translation
! again, pretty generic

nat (inside) 0 0.0.0.0 0.0.0.0 0 0
nat (dmz) 0 0.0.0.0 0.0.0.0 0 0

! here's where I apply the access-list to attempt to
! allow www traffic
access-group web in interface dmz
access-group web in interface outside

! my default route is up and working fine -- this might
! seem backward to you, but this is just a test network.
! I'm testing a single laptop on the "outside" to simulate
! customers accessing our web site, and our application
! servers are on the inside, in the typical way. -- Perhaps
! some might think this is the problem, but I kinda don't
! think so

route inside 0.0.0.0 0.0.0.0 xxx.xxx.xxx.xxx 1

! more typical stuff

timeout xlate 3:00:00
timeout h323 0:05:00 mgcp 0:05:00 sip 0:30:00 sip_media 0:02:00
timeout uauth 0:05:00 absolute

aaa-server TACACS+ protocol tacacs+
aaa-server TACACS+ max-failed-attempts 3
aa-server TACACS+ deadtime 10
aaa-server RADIUS protocol radius
aaa-server RADIUS max-failed-attempts 3
aaa-server RADIUS deadtime 10
aaa-server LOCAL protocol local

! stuff for PDM, which works
http server enable
http xxx.xxx.xxx.xxx 255.255.255.255 inside

no snmp-server location
no snmp-server contact
snmp-server community public
no snmp-server enable traps
floodguard enable
telnet timeout 5
ssh timeout 5
console timeout 0
terminal width 80

-------------------

Thanks in advance for any help.

B Squared




Posted by Brian V on July 19, 2005, 10:53 pm
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>
> The following is the configuration file for my PIX 515.
> For some reason I can no longer get any http packets to cross
> between the interfaces. This change first occurred when
> I turned off the fixup protocol for http, and then turned
> it back on. I posted a question about this about a week
> ago, but the concensus was that the fixup protocol issue
> probably wasn't the real problem.
>
> If this were a normal router, not a PIX, from the
> behavior I'd say it's either 1) A bad access list, or
> 2) the network statements haven't been entered correctly
> and the thing isn't routing. But the access list looks
> sufficently general to let http pass.
>
> For testing I always enter the IP address in decimal, not
> a web address so that DNS doesn't cloud the issue.
>
> By using the packet debug command I can see the packets
> at the outside interface whenever I point the browser
> at the web server in the dmz, but no packets ever come
> out of the dmz interface. This used to work just fine.
> I'm stumped!
>
> I've inserted some comments along the way to aid the
> discussion.
>
> ------------------------------------------
>
> PIX Version 6.3(4)
> ! this is all pretty normal
>
> interface ethernet0 auto
> interface ethernet1 auto
> interface ethernet2 auto
> nameif ethernet0 outside security0
> nameif ethernet1 inside security100
> nameif ethernet2 dmz security50
>
> ! naming stuff
> hostname pixfirewall
> domain-name our_domain_name.net
>
> ! the normal fixups, but I've turned ftp off
> fixup protocol dns
> no fixup protocol ftp 21
> fixup protocol h323 h225 1720
> fixup protocol h323 ras 1718-1719
> fixup protocol http 80
> fixup protocol rsh 514
> fixup protocol rtsp 554
> fixup protocol sip 5060
> fixup protocol sip udp 5060
> fixup protocol skinny 2000
> fixup protocol smtp 25
> fixup protocol sqlnet 1521
> fixup protocol tftp 69
>
> names
>
> ! for my basic testing I attempt to permit http and https
> ! in a very general way
>
> access-list web permit tcp any any eq www
> access-list web permit tcp any any eq https
> access-list web permit ip any any
>
>
> ! these are pretty much by the book
> pager lines 24
> mtu outside 1500
> mtu inside 1500
> mtu dmz 1500
>
> ! my addresses, as expected
>
> ip address outside xxx.xxx.xxx.xxx 255.255.255.224
> ip address inside xxx.xxx.xxx.xxx 255.255.255.0
> ip address dmz xxx.xxx.xxx.xxx 255.255.255.224
>
> ip audit info action alarm
> ip audit attack action alarm
>
> ! the pdm wasn't all the useful. it tells me I'm not
> ! getting any packets across the interfaces, which I knew
>
> pdm location xxx.xxx.xxx.xxx 255.255.255.255 inside
> pdm location xxx.xxx.xxx.xxx 255.255.0.0 outside
> pdm history enable
> arp timeout 14400
>
> ! use the inside and dmz addresses without translation
> ! again, pretty generic
>
> nat (inside) 0 0.0.0.0 0.0.0.0 0 0
> nat (dmz) 0 0.0.0.0 0.0.0.0 0 0
>
> ! here's where I apply the access-list to attempt to
> ! allow www traffic
> access-group web in interface dmz
> access-group web in interface outside
>
> ! my default route is up and working fine -- this might
> ! seem backward to you, but this is just a test network.
> ! I'm testing a single laptop on the "outside" to simulate
> ! customers accessing our web site, and our application
> ! servers are on the inside, in the typical way. -- Perhaps
> ! some might think this is the problem, but I kinda don't
> ! think so
>
> route inside 0.0.0.0 0.0.0.0 xxx.xxx.xxx.xxx 1
>
> ! more typical stuff
>
> timeout xlate 3:00:00
> timeout h323 0:05:00 mgcp 0:05:00 sip 0:30:00 sip_media 0:02:00
> timeout uauth 0:05:00 absolute
>
> aaa-server TACACS+ protocol tacacs+
> aaa-server TACACS+ max-failed-attempts 3
> aa-server TACACS+ deadtime 10
> aaa-server RADIUS protocol radius
> aaa-server RADIUS max-failed-attempts 3
> aaa-server RADIUS deadtime 10
> aaa-server LOCAL protocol local
>
> ! stuff for PDM, which works
> http server enable
> http xxx.xxx.xxx.xxx 255.255.255.255 inside
>
> no snmp-server location
> no snmp-server contact
> snmp-server community public
> no snmp-server enable traps
> floodguard enable
> telnet timeout 5
> ssh timeout 5
> console timeout 0
> terminal width 80
>
> -------------------
>
> Thanks in advance for any help.
>
> B Squared
>
>

Your not NATing....are you running registered IP's internally?




Posted by on July 19, 2005, 8:19 pm
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Brian V wrote:
>
>>The following is the configuration file for my PIX 515.
>>For some reason I can no longer get any http packets to cross
>>between the interfaces. This change first occurred when
>>I turned off the fixup protocol for http, and then turned
>>it back on. I posted a question about this about a week
>>ago, but the concensus was that the fixup protocol issue
>>probably wasn't the real problem.
>>
>>If this were a normal router, not a PIX, from the
>>behavior I'd say it's either 1) A bad access list, or
>>2) the network statements haven't been entered correctly
>>and the thing isn't routing. But the access list looks
>>sufficently general to let http pass.
>>
>>For testing I always enter the IP address in decimal, not
>>a web address so that DNS doesn't cloud the issue.
>>
>>By using the packet debug command I can see the packets
>>at the outside interface whenever I point the browser
>>at the web server in the dmz, but no packets ever come
>>out of the dmz interface. This used to work just fine.
>>I'm stumped!
>>
>>I've inserted some comments along the way to aid the
>>discussion.
>>
>>------------------------------------------

Configuration stuff deleted, but visible in the
main posting.


>>nat (inside) 0 0.0.0.0 0.0.0.0 0 0
>>nat (dmz) 0 0.0.0.0 0.0.0.0 0 0


>
> Your not NATing....are you running registered IP's internally?

Yes, we are running the registered IP's internally. That's the main
reason I XXX'd them out in my posting.

B Squared




Posted by Walter Roberson on July 20, 2005, 2:55 am
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:The following is the configuration file for my PIX 515.
:For some reason I can no longer get any http packets to cross
:between the interfaces.

:access-list web permit tcp any any eq www

:access-group web in interface dmz
:access-group web in interface outside

You can't share access-lists between interfaces. The access-list
is internally dynamically modified in order to handle adaptive security,
and modifying it for two interfaces simultaneously doesn't work.
--
'The short version of what Walter said is "You have asked a question
which has no useful answer, please reconsider the nature of the
problem you wish to solve".' -- Tony Mantler


Posted by on July 19, 2005, 8:29 pm
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Walter Roberson wrote:

> :The following is the configuration file for my PIX 515.
> :For some reason I can no longer get any http packets to cross
> :between the interfaces.
>
> :access-list web permit tcp any any eq www
>
> :access-group web in interface dmz
> :access-group web in interface outside
>
> You can't share access-lists between interfaces. The access-list
> is internally dynamically modified in order to handle adaptive security,
> and modifying it for two interfaces simultaneously doesn't work.

OK. I'm pretty sure I've it with the access-list on only the outside
interface, but I'll certainly try it tomorrow. While we're on the
subject, that this mean that if I want to apply an identical access-list
to both interfaces similar to this one, to permit www or https access
I have to write the access-list twice, but with different names, and
apply them, one to each interface.

For example, while we're testing the PIX, we'll want a mail server
in the DMZ, and one on the inside. And we'll want to allow access from
the outside to both of them, so that our clients wouldn't be cut off
from their mail. But later, cnce we got it working, all mail servers
would be moved into the DMZ. So the issue is more than just academic.



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