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seifdean
join:2014-04-11

seifdean

Member

How to configure PIX , public ip inside , private ip outside (ISP IP)

My ISP provide me 2 public IP (41.x.x.216/30) and private ip (172.30.19.76/30) to connect to the backbone ISP.

I have configured my PIX:

outside: private ip 172.30.19.78
inside: public ip 41.x.x.217

Then i added a route outside to gateway 172.30.19.77

then i used my laptop as 41.x.x.218

ping to 8.8.8.8 it works from my laptop

but from external to ping public ip 41.x.x.218 or 217 it doesnt work

Can someone help?

tubbynet
reminds me of the danse russe
MVM
join:2008-01-16
Gilbert, AZ

tubbynet

MVM

said by seifdean:

but from external to ping public ip 41.x.x.218 or 217 it doesnt work

have you permitted ping through your pix?
by default -- your "inside traffic" can flow to "outside" without issues due to security levels. higher can talk to lower without any issue. lower can only talk to higher with specific rulesets in place.

if you're trying to ping your pix -- not only do you need the rules allowed, but you'll also need to make sure you configure your pix to respond to icmp.

q.
HELLFIRE
MVM
join:2009-11-25

HELLFIRE to seifdean

MVM

to seifdean
said by seifdean:

outside: private ip 172.30.19.78
inside: public ip 41.x.x.217

Why you're using RFC1918 on your PIX OUTSIDE interface and non-RFC1918 on your INSIDE interface
I don't understand, but...
said by seifdean:

but from external to ping public ip 41.x.x.218 or 217 it doesnt work

If you have this set up like I'm guessing you have it set up, it's going to be DROPPED by the PIX
due to a) OUTSIDE to INSIDE is DENIED by default, unless explicitly permitted, and b) possible
NAT issues.

If you can, please post your config -- minus passwords and any other private information for review.

Regards
cramer
Premium Member
join:2007-04-10
Raleigh, NC
Westell 6100
Cisco PIX 501

cramer

Premium Member

The ISP is "conserving IPv4 addresses". (this is my preferred method, but it's highly discouraged in the networking community) On the plus side, one could use private addresses on the inside and use all four addresses via NAT -- if you assign the publics to a LAN, there has to be a network and broadcast address.

Yes, inbound traffic is denied by default. ("low security to high security") It is a *firewall* after all. (which is why I use "conduit permit icmp any any" on my PIXen)

tubbynet
reminds me of the danse russe
MVM
join:2008-01-16
Gilbert, AZ

tubbynet

MVM

said by cramer:

(this is my preferred method, but it's highly discouraged in the networking community)

cramer See Profile -- define 'networking community'.
most people that disagree with this are the same people who complain in their isp forums here on dslr that they see "rfc1918 addresses and its breaking the internetz!!!11!" because they don't understand the concept that the internet is just a network of networks and i can do whatever the shit i please inside of my a/s.

q.
cramer
Premium Member
join:2007-04-10
Raleigh, NC
Westell 6100
Cisco PIX 501

cramer

Premium Member

NANOG, IETF, ARIN, etc. (in general... people with more time to whine about it than manage their corners of the internet) There's only one valid reason, IMO, and it's more of an annoyance than "it'll break the internet, kick puppies, and eat kittens"... if the device needs to send an ICMP error message, sourcing that from a private address is a Bad Idea(tm) -- but the internet will still function if those packets (like any other packet) get lost.

(For the record, TWC's previous use of 10/8 for DHCP servers was only a slight annoyance as it runs into anti-spoofing filters on my side... minor tweak to allow it through. Today, it's in 142.254.0.0/32, so no exceptions are required.)

tubbynet
reminds me of the danse russe
MVM
join:2008-01-16
Gilbert, AZ

tubbynet

MVM

said by cramer:

NANOG

stopping reading right there.
i'm subscribed to nanog -- but it mostly gets dumped into a folder to ignore. aside from the usual bitching and complaining -- its really turned in to the isp version of a piss-poor /r forum.
said by cramer:

IETF

and they bitch about this -- but brought us 'carrier grade nat'. fucking hypocrites.



q.
cramer
Premium Member
join:2007-04-10
Raleigh, NC

cramer

Premium Member

Well, the IETF is a committee of committees...

tubbynet
reminds me of the danse russe
MVM
join:2008-01-16
Gilbert, AZ

1 recommendation

tubbynet

MVM

said by cramer:

Well, the IETF is a committee of committees

said by dogbert :
Dogbert's Group IQ Formula %u2014 The Intelligence Quotient of any meeting can be determined by starting with 100 and subtracting 5 points for each participant.

and thats all i have to say about that...

q.
markysharkey
Premium Member
join:2012-12-20
united kingd

markysharkey

Premium Member

Does that include video conferencing?
dee5330
join:2014-04-10

dee5330 to seifdean

Member

to seifdean
Can you post your running config?
Expand your moderator at work
seifdean
join:2014-04-11

seifdean

Member

Re: How to configure PIX , public ip inside , private ip outside (ISP IP)

This is my running config, i want you to understand my needs the 41.x.x.x/30 it's my public class which will be used by my servers, the 172.30.19.78 is the ip that i have to use to connect to backbone network where my gateway to internet 172.30.19.77

makpix# sh run
: Saved
:
PIX Version 6.3(5)145
interface ethernet0 auto
interface ethernet1 auto
nameif ethernet0 outside security0
nameif ethernet1 inside security100
enable password 8Ry2YjIyt7RRXU24 encrypted
passwd 2KFQnbNIdI.2KYOU encrypted
hostname makpix
domain-name alva-tn.com
fixup protocol dns maximum-length 512
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
access-list outside permit icmp any any echo-reply
access-list outside permit icmp any any time-exceeded
access-list outside permit icmp any any traceroute
access-list outside_access_in permit icmp any any
access-list outside_access_in permit tcp any any
pager lines 24
mtu outside 1500
mtu inside 1500
ip address outside 172.30.19.78 255.255.255.252
ip address inside 41.231.47.217 255.255.255.252
ip audit info action alarm
ip audit attack action alarm
failover timeout 0:00:00
pdm history enable
arp timeout 14400
global (outside) 1 interface
nat (outside) 1 172.y.19.78 255.255.255.255 0 0
nat (inside) 1 41.x.47.216 255.255.255.252 0 0
access-group outside_access_in in interface outside
route outside 0.0.0.0 0.0.0.0 172.30.19.77 1
timeout xlate 3:00:00
timeout conn 1:00:00 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
aaa-server TACACS+ protocol tacacs+
aaa-server TACACS+ max-failed-attempts 3
aaa-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
http server enable
http 172.x.19.76 255.255.255.252 inside
no snmp-server location
no snmp-server contact
snmp-server community public
no snmp-server enable traps
floodguard enable
telnet 41.x.47.216 255.255.255.252 inside
telnet timeout 5
ssh timeout 5
console timeout 0
dhcpd address 41.x.47.218-41.231.47.218 inside
dhcpd lease 3600
dhcpd ping_timeout 750
dhcpd enable inside
terminal width 120
Cryptochecksum:26fd1dadf0c735ea426e796fd90c3c1a
: end
HELLFIRE
MVM
join:2009-11-25

HELLFIRE to seifdean

MVM

to seifdean
Thanks for sharing your config. So these two lines are key :
said by seifdean:

access-list outside_access_in permit icmp any any
access-list outside_access_in permit tcp any any

said by seifdean:

access-group outside_access_in in interface outside

So it seems everyone's suspicions of not having the right ACL applied in the right direction's a bust.

For troubleshooting purposes, I'd modify your ACL to the following

access-list outside_access_in permit icmp any any log
access-list outside_access_in permit tcp any any log
access-list outside_access_in deny any any log


so you can see form syslog what's getting permitted / denied to troubleshoot.

What's a traceroute from an 'external' source to the 41.x.x.217 or .218 show, exactly? I'm wondering
if it isn't a routing issue.

Regards
seifdean
join:2014-04-11

seifdean

Member

1 10.10.0.254 0.738 ms 0.710 ms 0.788 ms
2 10.10.9.254 69.611 ms 69.404 ms 69.363 ms
3 192.168.69.10 26.361 ms 30.561 ms 28.913 ms
4 41.228.2.70 31.382 ms 33.600 ms 35.343 ms
5 193.95.96.237 36.060 ms 37.115 ms 37.797 ms
6 193.95.1.254 39.427 ms 39.770 ms 42.313 ms
7 193.95.96.2 42.278 ms 24.795 ms 25.465 ms
8 172.30.10.49 24.619 ms 25.376 ms 25.108 ms
9 * * *
10 * * *
11 172.30.19.145 25.426 ms 26.437 ms 27.479 ms
12 * * *
13 * * *
14 * * *
15 * * *
16 * * *
17 * * *
18 * * *
19 * * *
20 * * *
21 * * *
22 * * *
23 * * *
24 * * *
25 * * *
26 * * *
27 * * *
28 * * *
29 * * *
30 * * *

I don't know how see logs after enabling log on access-list
aryoba
MVM
join:2002-08-22

4 edits

aryoba to seifdean

MVM

to seifdean
said by seifdean:

global (outside) 1 interface
nat (outside) 1 172.y.19.78 255.255.255.255 0 0
nat (inside) 1 41.x.47.216 255.255.255.252 0 0

Based on your description, these three NAT statements should be replaced by either one of the following

Scenario 1:
Internet access only - no need to run Internet-accessible server
For outbound traffic only (traffic initiated from LAN out to the Internet).

nat (inside) 0 41.x.47.216 255.255.255.252
 

Scenario 2:
Internet access and Internet-accessible server service
For both inbound (from Internet coming in) and outbound traffic (from LAN coming out)

access-list inside-outside_nat_exemption permit ip 41.x.47.216 255.255.255.252 any
nat (inside) 0 access-list inside-outside_nat_exemption
 

Once you replace them, don't forget to issue clear xlate command to reset the firewall's NAT table.
said by seifdean:

http 172.x.19.76 255.255.255.252 inside

I don't think you have 172.x.19.76/30 network in your LAN. So this command is incorrect.
HELLFIRE
MVM
join:2009-11-25

HELLFIRE to seifdean

MVM

to seifdean
said by seifdean:

I don't know how to see logs after enabling log on access-list

"show log"
 

-or-

"show log | include (value here)"
 

from the ASA's CLI.

Regards