Ubuntu Servers :: Port 21 Reported Open By Nmap And Netcat, But Blocked By Iptables?
Oct 11, 2010
Strange issue here when trying to verify firewall on Server 8.04. No ftp service running at all on server, but both nmap and netcat report port 21 as being open, even though it isn't.I am 100% sure that port 21 is not actually accessible and iptables rules are fine. Trying to connect to the port fails, yet nmap and netcat seem to report a "false positive"?Have also checked on a number of other servers I'm running, and this "false positive" seems to apply to all of them.
I have a mail server on which I would like to block port 25 on my eth0 for everyone except our external spam filter. the problem is that I want our users to be able to connect via port 10025 which is forwarded to port 25, which then is blocked...
I am configuring an internal only IMAP server for archival emails. I am absolutely baffled why my connection is being refused. UFW is disabled and IPTABLES has a rule to allow all connections on 143 and 993. When I telnet this response is given:
Code: telnet localhost 143 Trying 127.0.0.1... telnet: Unable to connect to remote host: Connection refused Even nmap shows the port closed. Here is my iptables rule: HTML Code: -A ufw-user-input -p udp -m udp --dport 143 -j ACCEPT
I have a fresh installation of CentOS 5 I'm using for a server, and I'm having issues with port configuration. I have iptables running, and it started with no /etc/sysconfig/iptables file. I added a few basic rules (port 53, port 10000 for webmin), saved the file, and restarted the service. I tried connecting to webmin, scanned ports, and traffic was blocked. I set iptables to allow all traffic and restarted the service, and it still showed basically every port as being blocked. It seems port 80 and port 22 work for some reason, even when I tell iptables to block all ports.
I'm not sure what's going on here. Iptables is reading the /etc/sysconfig/iptables file, and if I use lynx localhost:someport it responds as it should according to the file. However, if I try connecting by IP, it's like there's some other firewall or something running that does whatever it's configured to do.....
I'm starting to like making bash scripts. It's kewl making creative ones. Right now I'm trying to make a bash script that will open up port 23 for a netcat connection. Once there's a connection, I'd like for the script to open up xmms and play a sound effect, as well as echo a txt file to the desktop saying that a connection was made at this specific time. When I execute the script, it stops exection at the first line. So far I have this:
Recently I discovered that we were accidentally running a POP server (port 110), when we only should have been running the encrypted version thereof (port 995). This wouldn't have been a problem if the port was blocked in the first place.Isn't the default iptables setup on CentOS to block unspecified ports? Specifically, this line from /etc/sysconfig/iptables
-A RH-Firewall-1-INPUT -j REJECT --reject-with icmp-host-prohibited
Right? Well, this doesn't seem to be working for me. I added some rules to allow additional ports and commented out a couple (crucially port 110), but for some reason, port 110 is open.Here is /etc/sysconfig/iptables and the output of iptables -L below that:
# cat /etc/sysconfig/iptables # Firewall configuration written by system-config-securitylevel # Manual customization of this file is not recommended. *filter :INPUT ACCEPT [0:0]
[code]....
Why isn't "-A RH-Firewall-1-INPUT -j REJECT --reject-with icmp-host-prohibited" doing what I think it should be doing?
If I forward port 80 to port 3128 for squid with an iptable rule, does port 3128 have to be open on the firewall or is this all routed behind the firewall?
i am running ncat (netcat's new version from nmap) on centos . I am listening on different ports. My question is , is it possible that when a connection is received on a port say 123, i redirect this connection to a different port and use the 123 port again for listening connections. ncat has an option -k which u can add with -l , it will force fully listen on the port. It can accept multiple connections on a single port but i want that once a client connects on to 123 port, he is forwarded to some other port and no longer on 123.
I've recently installed 10.10 server edition, and I must say it was a pleasant suprise, it's just the way I like it. I use it as a squeezebox-server. But I've run into a problem with the firewall. I did a portscan, which told me there are more ports open then I've told UFW to open. Among which port 25 and 119, when I telnet from another PC to those ports, the connection gets accepted, although there is no answer to any commands (as expected, there's no mail server running). Iptables print-outs also don't mention anything about the respective ports or a daemon that could be responsable, and the same applies to "ps -e" or "ps aux".
Iptables seems to be working, when I remove the rules to allow samba to work, I can't reach the shares, and when I insert them again I can reach the shares. "sudo ufw deny from any" as last rule doesn't change anything either (deny incoming is default (although I never issued the command "ufw status verbose" says it is) so it shouldn't, but ports 25 and 119 shouldn't be open either).
Is it possible to open dyndns port at iptables?I have a remote server which is cenots 5.5 x86 and uses iptable rules. And my local pc is windows 7 x64 and have a dyndns address as mypc.dyndns.org.I want to connect local pc with mypc.dyndns.org to remote server with iptable rules as follows.Quote:
# Xmanager -A RH-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp --dport 6000:6010 -s mypc.dyndns.org -j ACCEPT
I installed Ubuntu 9.10 and tomcat 6 java servlet container. I am trying to run the tomcat server on port 80, so I edited tomcat's configuration file (server.xml) and changed the default port from "8080" to "80". I launched tomcat server, went to my browser and entered:[url], but it says can not find server/location. Then I edit the server.xml and revert back to port "8080" and then enter: [url] and everything works fine. So my guess is some other service is taking up port 80, but I would think not, since I just installed Ubuntu and made sure apache isn't installed or running.
So I went to "System" --> "Administration", then choose "Network Tools". I then executed Netstat and did not see anything taking up port 80, but I do see port 8080 taken (assuming it is the tomcat server). Then I also did a Port Scan and entered my IP number. Again, I don't see port 80 taken, but do see 8080 being used.
I had a winxp laptop computer behind home wireless and was running tomcat 6 server fine with it, but it over-heated and died recently. So I got a used laptop and just installed Ubuntu 9.10. I have not changed my wireless router settings. It is the same as before. So I have ruled out my home's hardware/network equipment.
So here now I sit, wondering what is up?
For security reasons, is port 80 initially blocked by Ubuntu for some reason? Is there something I have to do beforehand to free up port 80?
VERY new to linux, erm but I have an issue that needs solving!I recently moved to university, where their network blocks sftp port 22, this means that I cannot connect to my FTP server which is running a version of linux.Now I've got this ftp server connected to a seedbox and it was created using the following walk through..Code:I have written this guide for a friend, but I though it would be useful for others as well.
There are several guides floating around, but I found that most always cock up in some way. This one is tried and tested to work on Debian Etch (on an OVH rps, but should apply to most servers).If there is a new stable release of rtorrent/libtorrent then I will update this guide to show you how to update it (without reinstalling the whole server).
At the bottom there are also instructions to install ftp access & some network monitoring software.Basically, I would really like someone to be able to construct the commands on how to change the listen port for sftp connection on linux or add another port to the list that Linux would use so that I could put in through putty.
I'm new to linux, but enjoy using it very much, especially without a GUI, console is fun! I need to set up port forwarding. We have 3 servers, 1x running Ubuntu server 8.04 (used as transparent proxy), 1x server 2003, 1x windows xp.
The linux box has the following ips: eth0 (internal) 192.168.1.5 eth1 (external) 192.168.0.7
Windows server 2003: 192.168.1.6
Windows XP: 192.168.1.9
Router: 192.168.0.1
The router automatically forwards specific ports to 196.168.0.7 (Linux eth0). From there I want to forward port 8585 to 192.168.1.6 and 3000 to 192.168.1.9. Is there a way that I can do this using iptables?
The commands that I think I'm gonna use look like this: iptables -A FORWARD -s 192.168.0.0/24 -p tcp --dport 8585 -d 192.168.1.6 -j ACCEPT iptables -A FORWARD -s 192.168.0.0/24 -p tcp --dport 3000 -d 192.168.1.9 -j ACCEPT
Would this be a correct way of doing it? My biggest problem is that I can't test it without going live, and if I go live and something doesn't work, the entire building will be left without internet, people will hate me. Also, The proxy captures all data on port 80 and forwards it to 3128 so that the proxy can monitor the usage, and a few systems runs fine with it, others however can ping websites, and internet explorer says "website found, waiting for reply" but the webpages cannot be displayed.
Since I no longer have access to a spare machine to actually test this out on, I was hoping some kind soul might know the answer, or be willing to try it out for me. I'm trying to find out if the port scanner nmap can detect two different services which are sharing a single port. For instance, if I'd managed to set up, I dunno, a web server and an ftp server to both run over the same port, would nmap with version detection be able to detect both of them, or just one?
Ultimately my DB will run in VM2 and any DB requests coming in at 2055 of VM1 should be forwarded to port 2055 of VM2. Since I do not yet have a DB running I am trying to test with netcat.
I'm trying to capture incoming/outgoing phone call data. Both telnet and nc have allowed me to easily direct this data to a file for later processing, HOWEVER I can't seem to get either to work as a background process. I want to put the connection into a shell script and run from cron.
I can seem to open port 25565 for a java application (executable jar) I'm running ubuntu server 9 thoroughly up to date code...
Yet connections to port 25565 fail when I have the firewall enabled (sudo ufw enable) For example canyouseeme.org says "Error: I could not see your service on port (25565) Reason: Connection timed out"
And connections to port 25565 _DO WORK_ when I disable the firewall (sudo ufw disable) canyouseeme.org says "Success: I can see your service on port (25565)"
I connect to the internet at work through an authenticating proxy, and to avoid having to enter the proxy info into every app I use (e.g. firefox, wget, kde, etc) I have set up squid as a local transparent proxy which authenticates and routes all traffic to the work proxy. It has been working fine, but lately I haven't been able to connect to any https sites. I don't think I have changed the configuration, so perhaps it is the result of an upgrade, or something badly configured on my system from the start. I have tried connecting to https sites without squid and iptables and it works fine. My system is Arch linux, and my squid.conf file is: Code:
acl all src all acl manager proto cache_object acl localhost src 127.0.0.1/32 acl to_localhost dst 127.0.0.0/8 acl SSL_ports port 443 acl Safe_ports port 80# http acl Safe_ports port 21# ftp acl Safe_ports port 443# https [Code]....
I have two computers on a LAN. (This is history not a Bazaar question, although I have one of those too) One of them (Ubuntu 9.04) Im using as a Bazaar repository over sftp. Its been working fine for about a year. Then we had a thunderstorm that knocked out our Internet service for a couple of days. When it came back up everything is working fine accept I could no longer commit to the server. A little detective work showed that ssh was not running on the server. I started it and Bazaar then couldnt find the repository files. I still suspected an ssh problem, but port scans from both computers showed port 22 open on the server and I could do a ssh login from the client ok. Then I started fiddling with ssh on the server and now I have ssh problems on top of the Bazaar problems.
On the server I deleted then regenerated the ssh keys. Ive done sudo /etc/init.d/ssh reload sudo /etc/init.d/ssh start
I get a normal starting message and ps ef |grep ssh
shows /usr/sbin/sshd running. But the port scan does not show 22 open and I get connection refused at the client.
I have nessus application is running in the target machine and the url
is https://hostname:8834/ - which is not accessible
But when i login in the target machine via ssh and check that this application and the service is running fine So i think it is blocked by the iptables in the same machine, where the nessus is running
So I set up an Ubuntu 10.04 server with apache2 installed, but for some reason I can't get to it from my browser. the iptables have all changed directories in 10.04 so I can't find the iptables. Apparmor wasn't the problem. The network hard ware is not the problem.There is something inside of 10.04 that is blocking port 80. I can ping it all day using the ip address but when I ping it useing http://ipaddress it can't find the host
