iptables help with rules Post: 302988728

Sponsored Content

Top Forums UNIX for Advanced & Expert Users iptables help with rules Post 302988728 by steadyonabix on Sunday 1st of January 2017 11:05:01 AM

01-01-2017

Registered User

Thanks, stomp,

That logging tip is really useful. Looks like I'm sending a SYN but not allowing a SYN-ACK if I'm understanding it correctly:

Code:

Dec 31 22:39:44 fwl kernel: [ 5336.614582] IN= OUT=eth0 SRC=10.10.1.1 DST=10.10.1.2 LEN=60 TOS=0x00 PREC=0x00 TTL=64 ID=48912 DF PROTO=TCP SPT=45562 DPT=22 WINDOW=29200 RES=0x00 SYN URGP=0
Dec 31 22:39:52 fwl kernel: [ 5344.634727] IN= OUT=eth0 SRC=10.10.1.1 DST=10.10.1.2 LEN=60 TOS=0x00 PREC=0x00 TTL=64 ID=48913 DF PROTO=TCP SPT=45562 DPT=22 WINDOW=29200 RES=0x00 SYN URGP=0
Dec 31 22:40:08 fwl kernel: [ 5360.654968] IN= OUT=eth0 SRC=10.10.1.1 DST=10.10.1.2 LEN=60 TOS=0x00 PREC=0x00 TTL=64 ID=48914 DF PROTO=TCP SPT=45562 DPT=22 WINDOW=29200 RES=0x00 SYN URGP=0

---------- Post updated at 04:05 PM ---------- Previous update was at 03:22 PM ----------

So my current set of rules is created like so:

Code:

root@fwl:~# cat fwl.cfg
#!/bin/sh

# Flushing all rules
#iptables -F
#iptables -X

# Logging rules
iptables -A INPUT -j LOG
iptables -A OUTPUT -j LOG
#iptables -A FORWARD -j LOG

# Setting default filter policy
iptables -P INPUT DROP
iptables -P OUTPUT DROP
iptables -P FORWARD DROP

# Allow unlimited traffic on loopback
iptables -A INPUT -i lo -j ACCEPT
iptables -A OUTPUT -o lo -j ACCEPT

# Allow ssh
iptables -A OUTPUT -p tcp --sport 22 -m conntrack --ctstate NEW,RELATED,ESTABLISHED -j ACCEPT
iptables -A INPUT  -p tcp  --dport 22 -m conntrack --ctstate NEW,RELATED,ESTABLISHED -j ACCEPT

#iptables -A INPUT  -p tcp  --dport 22  -j ACCEPT
#iptables -A OUTPUT -p tcp  --sport 22  -j ACCEPT

iptables -A OUTPUT -p tcp --dport 80 -m state --state NEW -j ACCEPT
iptables -A OUTPUT -p tcp --dport 53 -m state --state NEW,ESTABLISHED -j ACCEPT
iptables -A OUTPUT -p udp --dport 53 -m state --state NEW,ESTABLISHED -j ACCEPT

#iptables -A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT
#iptables -A OUTPUT -m state --state RELATED,ESTABLISHED -j ACCEPT

# Allow ping
iptables -A INPUT -p icmp --icmp-type echo-reply -j ACCEPT
iptables -A INPUT -p icmp --icmp-type echo-request -j ACCEPT
iptables -A OUTPUT -p icmp --icmp-type echo-reply -j ACCEPT
iptables -A OUTPUT -p icmp --icmp-type echo-request -j ACCEPT

When trying to make a connection from the fwl pi into one of the others I see a SYN go out but nothing back in my post of the log as shown above.

For the life of name I can't understand why or how to progress with investigating, so all suggestions welcome folks.

steadyonabix

View Public Profile for steadyonabix

Find all posts by steadyonabix

10 More Discussions You Might Find Interesting

1. Shell Programming and Scripting

SED inserting iptables rules in while loop

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. IP Networking

Iptables rules at boot

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...

3. Cybersecurity

Editing rules on iptables

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. Ubuntu

iptables rules (ubuntu)

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...

5. Red Hat

Iptables/Firewall rules for multicast IP.

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.

6. Red Hat

iptables Rules for my network

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...

7. UNIX for Advanced & Expert Users

Editing iptables rules with custom chain

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. ...

8. Shell Programming and Scripting

Need to Convert the QNX rules to UNIX iptables

Need to convert the QNX rules to Linux ubuntu 12.04. kindly any one help us with any tools

9. Cybersecurity

Need help for iptables rules

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...

10. IP Networking

iptables - formatting icmp rules

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...

LEARN ABOUT SUSE

iptables-apply

iptables-apply(8)					      System Manager's Manual						 iptables-apply(8)

NAME

       iptables-apply - a safer way to update iptables remotely

SYNOPSIS

       iptables-apply [-hV] [-t timeout] ruleset-file

DESCRIPTION

       iptables-apply  will  try  to  apply  a new ruleset (as output by iptables-save/read by iptables-restore) to iptables, then prompt the user
       whether the changes are okay. If the new ruleset cut the existing connection, the user will not be able to answer  affirmatively.  In  this
       case, the script rolls back to the previous ruleset after the timeout expired. The timeout can be set with -t.

       When called as ip6tables-apply, the script will use ip6tables-save/-restore instead.

OPTIONS

       -t seconds, --timeout seconds
	      Sets the timeout after which the script will roll back to the previous ruleset.

       -h, --help
	      Display usage information.

       -V, --version
	      Display version information.

SEE ALSO

       iptables-restore(8), iptables-save(8), iptables(8).

LEGALESE

       iptables-apply is copyright by Martin F. Krafft.

       This manual page was written by Martin F. Krafft <madduck@madduck.net>

       Permission is granted to copy, distribute and/or modify this document under the terms of the Artistic License 2.0.

								    2006-06-04							 iptables-apply(8)

10 More Discussions You Might Find Interesting

1. Shell Programming and Scripting

SED inserting iptables rules in while loop

Discussion started by: verbalicious

2. IP Networking

Iptables rules at boot

Discussion started by: solaris_user

3. Cybersecurity

Editing rules on iptables

Discussion started by: garric

4. Ubuntu

iptables rules (ubuntu)

Discussion started by: Greenice