Web browsing issue behind PIX

Web browsing issue behind PIX

Post by None » Fri, 02 Jun 2006 02:48:40



One of my PIX units (525 fail-over pair) on 6.3(5) is having trouble
browsing certain web sites - for example www.cnn.com and the "Microsoft
Update"  while "www.foxnews.com" and the "Windows Update" sites work
fine.  Anyone seen an issue like this?

TIA

 
 
 

Web browsing issue behind PIX

Post by Walter Robers » Fri, 02 Jun 2006 03:37:37




>One of my PIX units (525 fail-over pair) on 6.3(5) is having trouble
>browsing certain web sites - for example www.cnn.com and the "Microsoft
>Update"  while "www.foxnews.com" and the "Windows Update" sites work
>fine.  Anyone seen an issue like this?

Path MTU Discovery (PMTUD).

Ensure that you specifically permit icmp unreachable inward.

 
 
 

Web browsing issue behind PIX

Post by None » Fri, 02 Jun 2006 04:06:23





> >One of my PIX units (525 fail-over pair) on 6.3(5) is having trouble
> >browsing certain web sites - for example www.cnn.com and the "Microsoft
> >Update"  while "www.foxnews.com" and the "Windows Update" sites work
> >fine.  Anyone seen an issue like this?

> Path MTU Discovery (PMTUD).

> Ensure that you specifically permit icmp unreachable inward.

I pretty much have all ICMP open right now but still nothing on those
sites ...

access-list inside_access_in permit ip any any
access-list inside_access_in permit icmp any any
access-list outside_access_in permit icmp any any echo-reply
access-list outside_access_in permit icmp any any source-quench
access-list outside_access_in permit icmp any any unreachable
access-list outside_access_in permit icmp any any time-exceeded
access-list outside_access_in permit icmp any any

icmp permit any unreachable outside
icmp permit any source-quench outside
icmp permit any time-exceeded outside
icmp permit any outside
icmp permit any inside

 
 
 

Web browsing issue behind PIX

Post by Walter Robers » Fri, 02 Jun 2006 04:15:05







>> >One of my PIX units (525 fail-over pair) on 6.3(5) is having trouble
>> >browsing certain web sites - for example www.cnn.com and the "Microsoft
>> >Update"  while "www.foxnews.com" and the "Windows Update" sites work
>> >fine.  Anyone seen an issue like this?
>> Path MTU Discovery (PMTUD).
>I pretty much have all ICMP open right now but still nothing on those
>sites ...

Do you happen to be on DSL? If so then reduce your outside MTU
to 1492 (most providers; as low as 1398 for some providers!!)
 
 
 

Web browsing issue behind PIX

Post by None » Fri, 02 Jun 2006 05:01:58








> >> >One of my PIX units (525 fail-over pair) on 6.3(5) is having trouble
> >> >browsing certain web sites - for example www.cnn.com and the "Microsoft
> >> >Update"  while "www.foxnews.com" and the "Windows Update" sites work
> >> >fine.  Anyone seen an issue like this?

> >> Path MTU Discovery (PMTUD).

> >I pretty much have all ICMP open right now but still nothing on those
> >sites ...

> Do you happen to be on DSL? If so then reduce your outside MTU
> to 1492 (most providers; as low as 1398 for some providers!!)

No - it's in a CoLo with a 10mb burstable to 100mb feed
 
 
 

Web browsing issue behind PIX

Post by none » Fri, 02 Jun 2006 19:33:26




>> Do you happen to be on DSL? If so then reduce your outside MTU
>> to 1492 (most providers; as low as 1398 for some providers!!)

> No - it's in a CoLo with a 10mb burstable to 100mb feed

Update - a system on the DMZ can browse these sites - it's the inside
hosts that can't browse these websites.  I'll try to post the
configuration if I don't find the problem today.

Thanks for your help.

 
 
 

Web browsing issue behind PIX

Post by None » Sat, 03 Jun 2006 02:37:23


Here's my configuration below - the DMZ (DNSWEB) can browse all of the
sites while the "inside" hosts are the ones having problems with
getting to "www.cnn.com" ...

icctrade-pix# sh run
: Saved
:
PIX Version 6.3(5)
interface ethernet0 100full
interface ethernet1 100full
interface gb-ethernet0 1000full
interface gb-ethernet1 1000auto shutdown
nameif ethernet0 outside security0
nameif ethernet1 inside security100
nameif gb-ethernet0 dnsweb security4
nameif gb-ethernet1 intf3 security6
enable password xxx encrypted
passwd xxx encrypted
hostname xxx-pix
domain-name xxx.net
fixup protocol dns maximum-length 512
fixup protocol ftp 21
fixup protocol h323 h225 1720
fixup protocol h323 ras 1718-1719
no 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
access-list inside_access_in permit ip any any
access-list inside_access_in permit icmp any any
access-list outside_access_in permit icmp any any echo-reply
access-list outside_access_in permit icmp any any source-quench
access-list outside_access_in permit icmp any any unreachable
access-list outside_access_in permit icmp any any time-exceeded
access-list outside_access_in permit tcp any host 1.2.3.200 eq ftp
access-list outside_access_in permit tcp any host 1.2.3.232 eq domain
access-list outside_access_in permit udp any host 1.2.3.232 eq domain
access-list outside_access_in permit icmp any host 1.2.3.232
unreachable
access-list outside_access_in permit icmp any any
access-list outside_access_in permit icmp any host 1.2.3.200
unreachable
access-list dnsweb_access_in permit ip any any
access-list dnsweb_access_in permit icmp any any echo-reply
access-list dnsweb_access_in permit icmp any any source-quench
access-list dnsweb_access_in permit icmp any any unreachable
access-list dnsweb_access_in permit icmp any any time-exceeded
access-list woodward2icc permit ip any any
pager lines 24
icmp permit any unreachable outside
icmp permit any echo-reply outside
icmp permit any outside
icmp permit any source-quench outside
icmp permit any time-exceeded outside
icmp permit any inside
mtu outside 1500
mtu inside 1500
mtu dnsweb 1500
mtu intf3 1500
ip address outside 1.2.3.150 255.255.255.128
ip address inside 10.202.0.2 255.255.255.0
ip address dnsweb 10.203.0.1 255.255.255.0
no ip address intf3
ip audit info action alarm
ip audit attack action alarm
failover
failover timeout 0:00:00
failover poll 15
failover ip address outside 1.2.3.151
failover ip address inside 10.202.0.3
failover ip address dnsweb 10.203.0.2
no failover ip address intf3
pdm logging errors 200
pdm history enable
arp timeout 14400
global (outside) 10 1.2.3.201-1.2.3.215
global (outside) 10 1.2.3.216
global (dnsweb) 10 10.203.0.80-10.203.0.100
nat (inside) 10 10.202.0.0 255.255.255.0 0 0
nat (dnsweb) 10 10.203.0.0 255.255.255.0 0 0
nat (dnsweb) 10 0.0.0.0 0.0.0.0 0 0
static (dnsweb,outside) 1.2.3.232 10.203.0.232 netmask 255.255.255.255
0 0
static (inside,outside) 1.2.3.200 10.202.0.81 netmask 255.255.255.255 0
0
static (inside,dnsweb) 10.201.0.0 10.201.0.0 netmask 255.255.255.0 0 0
static (inside,dnsweb) 10.200.0.0 10.200.0.0 netmask 255.255.255.0 0 0
static (inside,dnsweb) 10.16.61.0 10.16.61.0 netmask 255.255.255.0 0 0
static (inside,dnsweb) 10.202.0.0 10.202.0.0 netmask 255.255.255.0 0 0
access-group outside_access_in in interface outside
access-group inside_access_in in interface inside
access-group dnsweb_access_in in interface dnsweb
rip inside default version 1
route outside 0.0.0.0 0.0.0.0 1.2.3.129 1
route inside 10.10.2.0 255.255.255.252 10.202.0.1 1
route inside 10.10.20.0 255.255.255.252 10.202.0.1 1
route inside 10.10.21.0 255.255.255.252 10.202.0.1 1
route inside 10.16.61.0 255.255.255.0 10.202.0.1 1
route inside 10.200.0.0 255.255.255.0 10.202.0.1 1
route inside 10.201.0.0 255.255.255.0 10.202.0.1 1
route inside 172.16.2.0 255.255.254.0 10.202.0.1 1
route inside 172.16.4.0 255.255.254.0 10.202.0.1 1
route inside 172.16.8.0 255.255.254.0 10.202.0.1 1
route inside 172.16.10.0 255.255.254.0 10.202.0.1 1
route inside 172.16.12.0 255.255.254.0 10.202.0.1 1
route inside 172.16.61.0 255.255.255.0 10.202.0.1 1
timeout xlate 3:00:00
timeout conn 24:00:00 half-closed 0:10:00 udp 0:02:00 rpc 0:10:00 h225
1:00:00
timeout h323 0:05:00 mgcp 0:05:00 sip 0:30:00 sip_media 0:02:00
timeout sip-disconnect 0:02:00 sip-invite 0:03:00
timeout uauth 0:05:00 absolute
http server enable
floodguard enable
sysopt connection permit-ipsec
ssh timeout 60
console timeout 0
terminal width 80

 
 
 

Web browsing issue behind PIX

Post by none » Sat, 03 Jun 2006 12:14:26


Issue resolved ...

I used Ethereal on one of the hosts and saw that the default router
couldn't find the hosts that were having this issue.  I compared this
default router with another default router behind another PIX and found
the only difference was that the unit on the working segment had "ip
classless" while the unit non working segment had "no ip classless"

I replaced "no ip classless" with "ip classless" on the default router for
the "Inside" network hosts and everything is working.  

 
 
 

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