Which ports should be open for a mail server for INPUT CHAIN? When I use firewall rules (allow just a few ports), some users complain that they're not receiving messages from other domains. When the firewall is disabled these ports show as open:
Code:
Not shown: 9987 closed ports
PORT STATE SERVICE
21/tcp open ftp
I will be relocating to a permanent residence sometime in the next year or two. I've recently begun thinking about the best way to implement a home-based network. It occurred to me that the most elegant solution might be the use of VM technology to eliminate as much hardware and wiring as possible.My thinking is this: Install a multi-core system and configure it to run several VMs, one each for a firewall, a caching proxy server, a mail server, a web server. Additionally, I would like to run 2-4 VMs as remote (RDP)workstations, using diskless workstations to boot the VMs over powerline ethernet.The latest powerline technology (available later this year) will allow multiple devices on a residential circuit operating at near gigabit speed, just like legacy wired networks.
In theory, the above would allow me to consolidate everything but the disklessworkstations on a single server and eliminate all wired (and wireless) connections except the broadband connection to the Internet and the cabling to the nearest power outlets. It appears technically possible, but I'm not sure about the various virtual connections among VMs. In theory, each VM should be able to communicate with the other as if it was on the same network via the server data bus, but what about setting up firewall zones? Any internal I/O bandwidth bottlenecks? Any other potential "gotchas", caveats, issues? (Other than the obvious requirement of having enough CPU and RAM).Any thoughts or observations welcome, especially if they are from real world experience in a VM environment. BTW--in case you're wondering why I'm posting here, it's because I run Debian on all my workstations/servers (running VirtualBox as a VM for Windows XP on one workstation).
I have just switched over from firestart to gufw.I have set all incoming traffic to deny and all outgoing traffic to allow.I have rules set for incoming traffic, and have only opened 1 port on my system for torrents. My router also only has the same port opened which again is for torrents.I use "Network Tools" which is included on squeeze and do a portscan of 192.168.1.100 and 127.0.0.1 I get all kinds of crazy ports coming back as opened. What is even stranger is if I do a few scans, these ports change, so one port on one scan may come up as open, then it will disappear and a different port may show as open.
Mind you none but the torrent port is forwarded in my router, I have no idea what any of these other ports are, or why they are even showing up.What the heck is going on? I dont think this is normal? Am I at any higher risk for attack?
how to open firewall ports without using yast. The reason I'm asking is because I'm working on a .sh script for the installation of a couple of programs. Some ports need to be open for the programs to work, I find it really annoying to go to yast and type the ports manually every time. I've looked at /etc/sysconfig/SuSEfirewall2 but can't seem to find anything, I also know that after the changes I will have to stop start the firewall by running:
I want to lock down my server to allow only certain ip addresses and ports in. I was thinking of doing this through the iptables but someone sugguested I used the hosts.allow and deny files to allow who can access the system. What do people suggest? If I"m trying to ensure no ip's can access my system except the ones I want, how would I do this with just the allow and deny files?
i need to add some ports in firewall(RHEL5) how can i do it using command or script or anything?? i know one method from graphic firewall wizzardtell me other shortcut to add more then one ports
I have a couple of openSUSE 11.2 machines and each is directly connected to the Internet (they are not behind a router, firewall, etc). I want them to be able to communicate without any firewall restrictions, but keep the firewall rules for all other IP addresses. Is this possible? the software package I'm trying to use randomly chooses a port to use in the range of 32768-61000 and I don't feel comfortable having a port range that wide open on both machines.
I am having trouble getting ports to open, on the router that the server is connected to it is set to DMZ, so everything passing through the router should go to the server right? but when I use a port checker none of the ports that I need to be open are. so my question is does ubuntu have a built in firewall that no one told me about? or something that would block me from having the ports open?
I have linux server setup on a network with 2 interfaces. One (eth0) is connected to the regular network and the other (eth1) has a DHCP server and transparent web cache listening on it. The machines connected on the eth1 side are on a different subnet and the linux server is there gateway. Untrusted machines are introduced to this network to keep them isolated.
This isolation works well, too well. There are a small set of resources on the regular network I would like to make available to machines on untrustworthy network. I think I need to use iptables but alas I've had no luck in piecing together the command I need (in one case looking myself out and having to physically reset the machine).
I would like to ask today how to open up specific ports in Linux firewall (iptables). Recently I have changed the SSH port in server from 22 to 30022 by typing
Code:
# vi /etc/ssh/sshd_config
Code:
Port 30022 "/etc/ssh/sshd_config" 111L, 3027C
And then for the iptables configuration file:
Code:
# vi /etc/sysconfig/iptables
[code]....
How to configure the iptables properly so that my Windows PC can access the Linux with port 30022?
I'm using opensuse 11.3 32bit with LXDE. I have configured an apache tomcat server listening on port 8080. Yast was used to open udp 8080 and tcp 8080 in the firewall by manual entry under the advanced button of 'allowed services' menu.Another system was used to access the tomcat server via a firefox webbrowser. The attempt was unsuccessful. The url used was [URL]. firefox webbrowser keeps showing'connecting ...' until timeout. I'm assuming that inspite of the specified port openings in the firewall, it is somehow ignored. If I were to disable the firewall, then I can access the tomcat server with the firefox webbrowser.
I am trying to understand why when running nmap against a SonicWALL firewall at a remote location, the SonicWall firewall is saying that most of its 65535 ports are open? I know this cant be correct and remember reading about how some of these network appliances are setup this way to thwart off attacks.
Small server running 5.3 - stock postfix configured to use Maildir. Dovecot configured but both pop and imap ports blocked by firewall. Access to mail is via Squirrelmail via https. Configured to virus scan via ClamAV. Works just fine. Now I want to add procmail filtering. So I create these two files - ~/.forward and ~/.procmailrc in my user home dir: "|exec /usr/bin/procmail -f- || exit 75 #mpeters"
I have a question about /etc/services file. If I open ports in firewall, do I need to alter /etc/services file in order for certain apps to work?
kpasswd 464/tcp # kpasswd kpasswd 464/udp # kpasswd # Theodore Ts'o <tytso&MIT.EDU> # 465 is illegal used by eMail Server smtps 465/tcp # eMail Server #urd 465/tcp # URL Rendesvous Directory for SSM igmpv3lite 465/udp # IGMP over UDP for SSM # Toerless Eckert <eckert&cisco.com> digital-vrc 466/tcp # digital-vrc digital-vrc 466/udp # digital-vrc
Above example shows if 465 tcp isn't altered, Postfix MTA fails to listen on 465 tcp port. What if there's a bigger span 3000:7000 TCP/UDP, is there a need to alter each line by hand?
I now have a firewall up and running: almost perfectly. When I use nmap and perform the most comprehensive scan I can think of, it cannot detect any wide open ports (unless bittorent is running) and cannot fingerprint the OS. My last 2 questions about my firewall (I am very happy now) are:
It seems as though Firestarter has been "abandoned" by the developers, and that gufw is more current. Does it really matter which firewall I use because don't they all do the same thing? I like firestarters system tray icon a lot. 2nd question is I have two open|filtered ports. Are these still pretty well protected?
It is very pleasing to see that I have no open ports, because if you were an experienced Windows user like I was, you got used to the fact you were going to have open ports no matter what. Linux's builtin firewall completely destroys the expensive and useless scams they call Norton and McAfee. Linux officially rocks now
Within the documentation of example OpenVPN setups there is a setup that shows an OpenVPN Server with two network interfaces. One interfaces is plugged into the public internet network and the second interface is plugged into the private network.
Normally I assume that it would be best to place the OpenVPN system inside the network behind the router and firewall and open only the ports needed on the router to allow access to the OpenVPN system. All other router ports would be closed. This is the first example they show. To see what I am talking about see page(s) 6-7 here -> [URL]
If one were to use the two interface public facing setup, when would that setup best be justified? I guess if you didn't want to open any ports on the router/firewall then this could be justified but then you have to lock down this public system individually instead of having it protected by the network firewall.
i have two questions and thought that anyone here could have the answers.first things first,i want to make firewall accept a range of ports (say 8000:9000) because im using mpd process manager to make some parallel processing, does anyone know the command that satisfy this?
the second thing is, when i open a range of ports like that, it would put my system at risk if some bad guys somehow identifies this range, is there is anything that solves that matter(i.e. makes the firewall monitor the packet, if its an mpd accept if not drop)
I have 2 mail servers behind Cisco firewall ,both the mail servers have different domain configured on them ,but when I try to send emails from server1 to server2 it dont go and also I am not able to receive emails in between two servers,after checking logs I found that the two server are not able to connect each other on SMTP port with public IP .
I am not able to connect any of my server with public IP behind firewall.
I'm encountering a strange problem. I need to open and forward all UDP and TCP ports related to VoIPtelephony (5000:32000) in the Suse 11.1 server that's acting as router/firewall in our setup. The ports must redirect to a Asterisk server in the local network. (This server has the IP adress 192.168.0.3)I've opened ports in Yast (Firewall>Ports>Advanced) and putted in some masquerading rulesirewall>Masquerading):0/0,192.168.0.3,tcp,5000:31000,5000:310000/0,192.168.0.3,udp,5000:31000,5000:31000when I do a nmap localhost I get:Starting Nmap 4.75 at 2010-01-08 16:52 CETInteresting ports on localhost (127.0.0.1):
Not shown: 991 closed ports PORT STATE SERVICE 21/tcp open ftp
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I have a problem relate to posttfix.I want to mirgare postfix mail server to exchange 2010 mail server but I can't do it,u can help me.You can show me have to do configure postfix and exchange how to?
Can this be done? A company is currently running a postfix mail server. They got a new server and, while the users are migrated, they need to have the messages delivered on BOTH servers.
I thought it could be easily done in postfix: deliver locally AND forward mail to new server, but all solutions I found would deliver the messages in just ONE place.
How do I make a local mail server that itself is a client to a WAN mail server.I want the local mail server to query new mail every 30 minutes from the WAN server.
There is an requirement, intranet people they may not have internet access but they want to send mail to external domain(internet),but in that intranet network one machine can have internet access. Is there any solution for this requirement.
I've setup my server by following a ton of goods, and it seems to work ok, but I need to start using my server for email in order to receive orders placed via my website. I've followed this guide - [URL] I followed the steps above, and tested the mail server via telnet, and all seemed to be ok. I tried sending an email via Squirrelmail, from cs@thinclientwarehouse.co.uk TO my working email simon@c1systems.co.uk, but the server returned with the following message:
<simon@c1systems.co.uk>: host mail.c1systems.co.uk[95.128.128.129] said: 550-Verification failed for <cs@localhost.thinclientwarehouse.co.uk> 550-The mail server could not deliver mail to cs@localhost.thinclientwarehouse.co.uk. The account or domain may not exist, they may be blacklisted, or missing the proper dns entries. 550 Sender verify failed (in reply to RCPT TO command)