diff --git a/Shorewall-docs/FAQ.xml b/Shorewall-docs/FAQ.xml index 7b215400a..094de33a2 100644 --- a/Shorewall-docs/FAQ.xml +++ b/Shorewall-docs/FAQ.xml @@ -15,7 +15,7 @@ - 2003-12-04 + 2003-12-09 2001 - 2003 @@ -24,6 +24,16 @@ + + 1.2 + + 2003-12-09 + + TE + + Added Copyright and legacy FAQ numbers + + 1.1 @@ -55,9 +65,9 @@ Port Forwarding
- I want to forward UDP port 7777 to my my personal PC with IP - address 192.168.1.5. I've looked everywhere and can't find how - to do it. + (FAQ 1) I want to forward UDP port 7777 to my my personal PC with + IP address 192.168.1.5. I've looked everywhere and can't find + how to do it. Answer: The first example in the low-port:high-port.
- Ok -- I followed those instructions but it doesn't work + (FAQ 1a) Ok -- I followed those instructions but it doesn't + work Answer: That is usually the result of one of three things: @@ -221,7 +232,7 @@
- I'm still having problems with port forwarding + (FAQ 1b) I'm still having problems with port forwarding Answer: To further diagnose this problem: @@ -284,8 +295,8 @@
- From the internet, I want to connect to port 1022 on my - firewall and have the firewall forward the connection to port 22 on + <title>(FAQ 1c) From the internet, I want to connect to port 1022 on + my firewall and have the firewall forward the connection to port 22 on local system 192.168.1.3. How do I do that? In /etc/shorewall/rules: @@ -333,8 +344,8 @@
- I'm confused about when to use DNAT rules and when to use - ACCEPT rules. + (FAQ 30) I'm confused about when to use DNAT rules and when + to use ACCEPT rules. It would be a good idea to review the QuickStart Guide @@ -353,7 +364,7 @@ DNS and Port Forwarding/NAT
- I port forward www requests to www.mydomain.com (IP + <title>(FAQ 2) I port forward www requests to www.mydomain.com (IP 130.151.100.69) to system 192.168.1.5 in my local network. External clients can browse http://www.mydomain.com but internal clients can't. @@ -527,10 +538,11 @@
- I have a zone "Z" with an RFC1918 subnet and I use - one-to-one NAT to assign non-RFC1918 addresses to hosts in Z. Hosts in - Z cannot communicate with each other using their external (non-RFC1918 - addresses) so they can't access each other using their DNS names. + (FAQ 2a) I have a zone "Z" with an RFC1918 subnet and I + use one-to-one NAT to assign non-RFC1918 addresses to hosts in Z. + Hosts in Z cannot communicate with each other using their external + (non-RFC1918 addresses) so they can't access each other using + their DNS names. If the ALL INTERFACES column in /etc/shorewall/nat is empty or @@ -685,8 +697,8 @@ Subnet: 192.168.2.0/24 Netmeeting/MSN
- I want to use Netmeeting or MSN Instant Messenger with Shorewall. - What do I do? + (FAQ 3) I want to use Netmeeting or MSN Instant Messenger with + Shorewall. What do I do? Answer: There is an H.323 @@ -702,8 +714,9 @@ Subnet: 192.168.2.0/24 Open Ports
- I just used an online port scanner to check my firewall and it - shows some ports as 'closed' rather than 'blocked'. Why? + (FAQ 4) I just used an online port scanner to check my firewall + and it shows some ports as 'closed' rather than + 'blocked'. Why? Answer: The common.def included with version 1.3.x always rejects connection requests on TCP port 113 @@ -721,8 +734,8 @@ Subnet: 192.168.2.0/24 of your Service Agreement.
- I just ran an nmap UDP scan of my firewall and it showed 100s - of ports as open!!!! + (FAQ 4a) I just ran an nmap UDP scan of my firewall and it + showed 100s of ports as open!!!! Answer: Take a deep breath and read the nmap man page section about UDP scans. If nmap gets
- I have a port that I can't close no matter how I change my - rules. + (FAQ 4b) I have a port that I can't close no matter how I + change my rules. I had a rule that allowed telnet from my local network to my firewall; I removed that rule and restarted Shorewall but my telnet @@ -748,7 +761,7 @@ Subnet: 192.168.2.0/24
- How to I use Shorewall with PortSentry? + (FAQ 4c) How to I use Shorewall with PortSentry? Here's @@ -761,8 +774,8 @@ Subnet: 192.168.2.0/24 Connection Problems
- I've installed Shorewall and now I can't ping through the - firewall + (FAQ 5) I've installed Shorewall and now I can't ping + through the firewall Answer: If you want your firewall to be totally open for "ping", @@ -789,7 +802,7 @@ Subnet: 192.168.2.0/24
- My local systems can't see out to the net + (FAQ 15) My local systems can't see out to the net Answer: Every time I read "systems can't see out to the net", I wonder where the @@ -817,7 +830,7 @@ Subnet: 192.168.2.0/24
- FTP Doesn't Work + (FAQ 29) FTP Doesn't Work See the Shorewall and FTP page.
@@ -827,8 +840,8 @@ Subnet: 192.168.2.0/24 Logging
- Where are the log messages written and how do I change the - destination? + (FAQ 6) Where are the log messages written and how do I change + the destination? Answer: NetFilter uses the kernel's equivalent of syslog (see "man syslog") to log @@ -853,7 +866,7 @@ LOGBURST="" to a separate file.
- Are there any log parsers that work with Shorewall? + (FAQ 6a) Are there any log parsers that work with Shorewall? Answer: Here are several links that may be helpful: @@ -872,9 +885,9 @@ url="http://www.shorewall.net/pub/shorewall/parsefw/">http://www.shorewall.net/p
- DROP messages on port 10619 are flooding the logs with their - connect requests. Can i exclude these error messages for this port - temporarily from logging in Shorewall? + (FAQ 2b) DROP messages on port 10619 are flooding the logs with + their connect requests. Can i exclude these error messages for this + port temporarily from logging in Shorewall? Temporarily add the following rule: @@ -927,8 +940,8 @@ run_iptables -A common -p udp --sport 53 -mstate --state NEW -j DROP
- Why is the MAC address in Shorewall log messages so long? I - thought MAC addresses were only 6 bytes in length. + (FAQ 6c) Why is the MAC address in Shorewall log messages so + long? I thought MAC addresses were only 6 bytes in length. What is labeled as the MAC address in a Shorewall log message is actually the Ethernet frame header. IT contains: @@ -970,8 +983,8 @@ run_iptables -A common -p udp --sport 53 -mstate --state NEW -j DROP
- Shorewall is writing log messages all over my console making it - unusable! + (FAQ 16) Shorewall is writing log messages all over my console + making it unusable! Answer: If you are running Shorewall version 1.4.4 or 1.4.4a then check the errata. @@ -983,7 +996,7 @@ run_iptables -A common -p udp --sport 53 -mstate --state NEW -j DROP
- How do I find out why this traffic is getting logged? + (FAQ 17) How do I find out why this traffic is getting logged? Answer: Logging occurs out of a number of chains (as indicated in the log message) in Shorewall: @@ -1190,7 +1203,8 @@ PROTO=UDP SPT=1803 DPT=53 LEN=47
- I see these strange log entries occasionally; what are they? + I (FAQ 21) see these strange log entries occasionally; what are + they? Nov 25 18:58:52 linux kernel: Shorewall:net2all:DROP:IN=eth1 OUT= MAC=00:60:1d:f0:a6:f9:00:60:1d:f6:35:50:08:00 SRC=206.124.146.179 DST=192.0.2.3 LEN=56 TOS=0x00 PREC=0x00 TTL=110 ID=18558 PROTO=ICMP TYPE=3 CODE=3 @@ -1236,7 +1250,7 @@ PROTO=UDP SPT=1803 DPT=53 LEN=47 Routing
- My firewall has two connections to the internet from two + <title>(FAQ 32) My firewall has two connections to the internet from two different ISPs. How do I set this up in Shorewall? Setting this up in Shorewall is easy; setting up the routing is a @@ -1464,8 +1478,8 @@ nexthop via $P2 dev $IF2 weight 1 Starting and Stopping
- When I stop Shorewall using 'shorewall stop', I can't - connect to anything. Why doesn't that command work? + (FAQ 7) When I stop Shorewall using 'shorewall stop', I + can't connect to anything. Why doesn't that command work? The 'stop' command is intended to place your firewall into a safe state whereby only those hosts listed in @@ -1475,8 +1489,8 @@ nexthop via $P2 dev $IF2 weight 1
- When I try to start Shorewall on RedHat, I get messages about - insmod failing -- what's wrong? + (FAQ 8) When I try to start Shorewall on RedHat, I get messages + about insmod failing -- what's wrong? Answer: The output you will see looks something like this: @@ -1509,7 +1523,8 @@ rmmod ipchains
- Why can't Shorewall detect my interfaces properly at startup? + (FAQ 9) Why can't Shorewall detect my interfaces properly at + startup? I just installed Shorewall and when I issue the start command, I see the following: @@ -1539,8 +1554,8 @@ Creating input Chains...
- I have some iptables commands that I want to run when Shorewall - starts. Which file do I put them in? + ( FAQ 22) I have some iptables commands that I want to run when + Shorewall starts. Which file do I put them in? You can place these commands in one of the Shorewall Extension Scripts. @@ -1559,21 +1574,21 @@ Creating input Chains... About Shorewall
- What Distributions does it work with? + (FAQ 10) What Distributions does it work with? Shorewall works with any GNU/Linux distribution that includes the proper prerequisites.
- What Features does it have? + (FAQ 11) What Features does it have? Answer: See the Shorewall Feature List.
- Is there a GUI? + (FAQ 12) Is there a GUI? Answer: Yes. Shorewall support is included in Webmin 1.060 and later versions. See
- Why do you call it "Shorewall"? + (FAQ 13) Why do you call it "Shorewall"? Answer: Shorewall is a concatenation of "Shoreline" (
- Why do you use such ugly fonts on your web site? + (FAQ 23) Why do you use such ugly fonts on your web site? The Shorewall web site is almost font neutral (it doesn't explicitly specify fonts except on a few pages) so the fonts you see are @@ -1601,7 +1616,7 @@ Creating input Chains...
- How to I tell which version of Shorewall I am running? + (FAQ 25) How to I tell which version of Shorewall I am running? At the shell prompt, type: @@ -1609,7 +1624,7 @@ Creating input Chains...
- Does Shorewall provide protection against.... + (FAQ 31) Does Shorewall provide protection against.... @@ -1672,10 +1687,10 @@ Creating input Chains... RFC 1918
- I'm connected via a cable modem and it has an internal web - server that allows me to configure/monitor it but as expected if I - enable rfc1918 blocking for my eth0 interface (the internet one), it - also blocks the cable modems web server. + (FAQ 14) I'm connected via a cable modem and it has an + internal web server that allows me to configure/monitor it but as + expected if I enable rfc1918 blocking for my eth0 interface (the + internet one), it also blocks the cable modems web server. Is there any way it can add a rule before the rfc1918 blocking that will let all traffic to and from the 192.168.100.1 address of the @@ -1747,9 +1762,10 @@ Creating input Chains...
- Even though it assigns public IP addresses, my ISP's DHCP - server has an RFC 1918 address. If I enable RFC 1918 filtering on my - external interface, my DHCP client cannot renew its lease. + (FAQ 14a) Even though it assigns public IP addresses, my + ISP's DHCP server has an RFC 1918 address. If I enable RFC 1918 + filtering on my external interface, my DHCP client cannot renew its + lease. The solution is the same as above. Simply substitute the IP address of your ISPs DHCP server. @@ -1761,8 +1777,8 @@ Creating input Chains... Alias IP Addresses/Virtual Interfaces
- Is there any way to use aliased ip addresses with Shorewall, and - maintain separate rulesets for different IPs? + (FAQ 18) Is there any way to use aliased ip addresses with + Shorewall, and maintain separate rulesets for different IPs? Answer: Yes. See Shorewall and Aliased @@ -1774,8 +1790,8 @@ Creating input Chains... Miscellaneous
- I have added entries to /etc/shorewall/tcrules but they don't - seem to do anything. Why? + (FAQ 19) I have added entries to /etc/shorewall/tcrules but they + don't seem to do anything. Why? You probably haven't set TC_ENABLED=Yes in /etc/shorewall/shorewall.conf so the contents of the tcrules file are @@ -1783,8 +1799,8 @@ Creating input Chains...
- I have just set up a server. Do I have to change Shorewall to - allow access to my server from the internet? + (FAQ 20) I have just set up a server. Do I have to change + Shorewall to allow access to my server from the internet? Yes. Consult the QuickStart guide that you used during your initial setup for information @@ -1792,8 +1808,8 @@ Creating input Chains...
- How can I allow conections to let's say the ssh port only - from specific IP Addresses on the internet? + (FAQ 24) How can I allow conections to let's say the ssh port + only from specific IP Addresses on the internet? In the SOURCE column of the rule, follow "net" by a colon and a list of the host/subnet addresses as a comma-separated list. @@ -1808,18 +1824,18 @@ Creating input Chains...
- When I try to use any of the SYN options in nmap on or behind the - firewall, I get "operation not permitted". How can I use nmap - with Shorewall?" + (FAQ 26) When I try to use any of the SYN options in nmap on or + behind the firewall, I get "operation not permitted". How can I + use nmap with Shorewall?" Edit /etc/shorewall/shorewall.conf and change "NEWNOTSYN=No" to "NEWNOTSYN=Yes" then restart Shorewall.
- When I try to use the "-O" option of nmap from the - firewall system, I get "operation not permitted". How to I - allow this option? + (FAQ 26a) When I try to use the "-O" option of nmap + from the firewall system, I get "operation not permitted". How + to I allow this option? Add this command to your /etc/shorewall/start file: @@ -1828,8 +1844,8 @@ Creating input Chains...
- I'm compiling a new kernel for my firewall. What should I - look out for? + (FAQ 27) I'm compiling a new kernel for my firewall. What + should I look out for? First take a look at the Shorewall kernel configuration page. You probably also want to be sure that you @@ -1840,7 +1856,7 @@ Creating input Chains...
- How do I use Shorewall as a Bridging Firewall? + (FAQ 28) How do I use Shorewall as a Bridging Firewall? Basically, you don't. While there are kernel patches that allow you to route bridge traffic through Netfilter, the environment is