Hi, I am relatively new to firewalls and netfilter. I have a Debian Stretch router box running dnsmasq, connected to a VPN. Occasionally dnsmasq polls all of the desired DNS servers to select the fastest. When it does this it responds to replies of the non-selected DNS servers with a icmp type three or "host unreachable". My firewall is very strict (I was hacked) and I am controlling sockets. I would like to respond to the DNS servers with this icmp message. I have tried many, many ways but none work, the message keeps on getting dropped. Here is an example rule set for one of the DNS servers:
Here is the rule script:
Here is the resulting script from the firewall log:
To me the firewall is not seeing the icmp rule for some reason. Can anyone see the problem? Thanks for you help!
---------- Post updated at 06:04 PM ---------- Previous update was at 05:36 PM ----------
Well, I'm replying to my own post 10 minutes after writing it. All I needed was a "RELATED" on the state. I was hesitant to use this state as it seems to open a can of worms on some web sites...
I'm trying to insert multiple new lines of text into an iptables script using sed in a while loop. I'm not sure if this is the most effective way. Searching the forums has helped me come up with a good beginning but it's not 100%. I'd like it to search out a unique line in my current iptables file... (2 Replies)
Hi
I have small home network and I want to block some forums on web
When I use this
iptables -A INPUT -s forum -j DROP
rules is applied but when I restart some of PC rules are not present any more also I tried to save firewall settings
iptables-save > /root/dsl.fw
but how to... (2 Replies)
Hello,
I was playing around with iptables to setup an isolated system. On a SLES10 system, I ran the below to setup my first draft of rules. I noticed that the rules come into effect immediately and do not require any restart of iptables.
iptables -A INPUT -j ACCEPT
iptables -A OUTPUT -m... (4 Replies)
Could someone help me with writing rules for iptables?
I need a dos attacks protection for a game server.
port type udp
ports 27015:27030
interface: eth0
Accept all packets from all IPs
Chek if IP sent more than 50 packets per second
Drop all packets from this IP for 5 minutes
I would be... (0 Replies)
Hi Gurus,
I need to add Multicast Port = xyz
Multicast Address = 123.134.143 ( example) to my firewall rules. Can you please guide me with the lines I need to update my iptables files with. (0 Replies)
Hi Champs
i am new in Iptables and trying to write rules for my Samba server.I took some help from internet, created one script and run from rc.local :
#Allow loopback
iptables -I INPUT -i lo -j ACCEPT
# Accept packets from Trusted network
iptables -A INPUT -s my-network/subnet -j... (0 Replies)
Hello,
I have iptables service running on my CentOS5 server. It has approx 50 rules right now.
The problem I am facing now is as follows -
I have to define a new chain in the filter table, say DOS_RULES & add all rules in this chain starting from index number 15 in the filter table.
... (1 Reply)
Hi,
I've been struggling with this all morning and seem to have a blind spot on what the problem is. I'm trying to use iptables to block traffic on a little cluster of raspberry pi's but to allow ssh and ping traffic within it.
The cluster has a firewall server with a wifi card connecting to... (4 Replies)
Hello,
I did 2 scripts. The second one is, I hope, more secure.
What do you think?
Basic connection (no server, no router, no DHCP and the Ipv6 is disabled)
#######script one
####################
iptables -F
iptables -X -t filter
iptables -P INPUT DROP
iptables -P FORWARD... (6 Replies)
Discussion started by: Thomas342
6 Replies
LEARN ABOUT DEBIAN
shorewall-tcfilters
SHOREWALL-TCFILTERS(5) [FIXME: manual] SHOREWALL-TCFILTERS(5)NAME
tcfilters - Shorewall u32 classifier rules file
SYNOPSIS
/etc/shorewall/tcfilters
DESCRIPTION
Entries in this file cause packets to be classified for traffic shaping.
Beginning with Shorewall 4.4.15, the file may contain entries for both IPv4 and IPv6. By default, all rules apply to IPv4 but that can be
changed by inserting a line as follows:
IPV4
Following entries apply to IPv4.
IPV6
Following entries apply to IPv6
ALL
Following entries apply to both IPv4 and IPv6. Each entry is processed twice; once for IPv4 and once for IPv6.
The columns in the file are as follows (where the column name is followed by a different name in parentheses, the different name is used in
the alternate specification syntax).
CLASS - interface:class
The name or number of an interface defined in shorewall-tcdevices[1](5) followed by a class number defined for that interface in
shorewall-tcclasses[2](5).
SOURCE - {-|address}
Source of the packet. May be a host or network address. DNS names are not allowed.
DEST - {-|address}}
Destination of the packet. May be a host or network address. DNS names are not allowed.
You may exclude certain hosts from the set already defined through use of an exclusion (see shorewall-exclusion[3](5)).
PROTO - {-|protocol-number|protocol-name|all}
Protocol.
DEST PORT (dport) - [-|port-name-or-number]
Optional destination Ports. A Port name (from services(5)) or a port number; if the protocol is icmp, this column is interpreted as the
destination icmp-type(s).
SOURCE PORT (sport) - [-|port-name-or-number]
Optional source port.
TOS (Optional) - [-|tos]
Specifies the value of the TOS field. The tos value can be any of the following:
o tos-minimize-delay
o tos-maximuze-throughput
o tos-maximize-reliability
o tos-minimize-cost
o tos-normal-service
o hex-number
o hex-number/hex-number
The hex-numbers must be exactly two digits (e.g., 0x04)x.
LENGTH - [-|number]
Optional - Must be a power of 2 between 32 and 8192 inclusive. Packets with a total length that is strictly less than the specified
number will match the rule.
EXAMPLE
Example 1:
Place all 'ping' traffic on interface 1 in class 10. Note that ALL cannot be used because IPv4 ICMP and IPv6 ICMP are two different
protocols.
#CLASS SOURCE DEST PROTO DEST
# PORT
IPV4
1:10 0.0.0.0/0 0.0.0.0/0 icmp echo-request
1:10 0.0.0.0/0 0.0.0.0/0 icmp echo-reply
IPV6
1:10 ::/0 ::/0 icmp6 echo-request
1:10 ::/0 ::/0 icmp6 echo-reply
FILES
/etc/shorewall/tcfilters
SEE ALSO
http://shorewall.net/traffic_shaping.htm
http://shorewall.net/MultiISP.html
http://shorewall.net/PacketMarking.html
http://shorewall.net/configuration_file_basics.htm#Pairs
shorewall(8), shorewall-accounting(5), shorewall-actions(5), shorewall-blacklist(5), shorewall-ecn(5), shorewall-exclusion(5),
shorewall-hosts(5), shorewall_interfaces(5), shorewall-ipsets(5), shorewall-maclist(5), shorewall-masq(5), shorewall-nat(5),
shorewall-netmap(5), shorewall-params(5), shorewall-policy(5), shorewall-providers(5), shorewall-proxyarp(5), shorewall-rtrules(5),
shorewall-routestopped(5), shorewall-rules(5), shorewall.conf(5), shorewall-secmarks(5), shorewall-tcclasses(5), shorewall-tcdevices(5),
shorewall-tos(5), shorewall-tunnels(5), shorewall-zones(5)NOTES
1. shorewall-tcdevices
http://www.shorewall.net/manpages/shorewall-tcdevices.html
2. shorewall-tcclasses
http://www.shorewall.net/manpages/shorewall-tcclasses.html
3. shorewall-exclusion
http://www.shorewall.net/manpages/shorewall-exclusion.html
[FIXME: source] 06/28/2012 SHOREWALL-TCFILTERS(5)