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Old 05-16-2004, 04:02 AM   #1
Registered: Apr 2004
Distribution: Ubuntu 7.10
Posts: 31

Rep: Reputation: 15
Firewall seems configured properly, but still can't open ports needed

Hello. This is a continuation of the problem discussed in the following threads:

I'm running RH 9 with kernel 2.4.8-20. I need to open ports 8000 and 8001 for a SHOUTcast streaming server. I have successfully used this server on the same IP address over Windows and Mac, so I know the network is not the problem.

My iptables seem configured properly, unless someone can please tell me of any errors here that might be causing the problem. Notice that ports 8000 and 8001 are set to "ACCEPT". There's also an additional filter suggested by a fellow SHOUTcast broadcaster designed specifically to open 8000 and 8001:

# Firewall configuration written by lokkit
# Manual customization of this file is not recommended.
# Note: ifup-post will punch the current nameservers through the
# firewall; such entries will *not* be listed here.
:RH-Lokkit-0-50-INPUT - [0:0]
-A INPUT -j RH-Lokkit-0-50-INPUT
-A FORWARD -j RH-Lokkit-0-50-INPUT
-A RH-Lokkit-0-50-INPUT -p tcp -m tcp --dport 7998 --syn -j ACCEPT
-A RH-Lokkit-0-50-INPUT -p tcp -m tcp --dport 7999 --syn -j ACCEPT
-A RH-Lokkit-0-50-INPUT -p tcp -m tcp --dport 8000 --syn -j ACCEPT
-A RH-Lokkit-0-50-INPUT -p tcp -m tcp --dport 8001 --syn -j ACCEPT
-A RH-Lokkit-0-50-INPUT -p tcp -m tcp --dport 22 --syn -j ACCEPT
-A RH-Lokkit-0-50-INPUT -p tcp -m tcp --dport 23 --syn -j ACCEPT
-A RH-Lokkit-0-50-INPUT -p tcp -m tcp --dport 25 --syn -j ACCEPT
-A RH-Lokkit-0-50-INPUT -p tcp -m tcp --dport 80 --syn -j ACCEPT
-A RH-Lokkit-0-50-INPUT -p tcp -m tcp --dport 21 --syn -j ACCEPT
-A RH-Lokkit-0-50-INPUT -i lo -j ACCEPT
-A RH-Lokkit-0-50-INPUT -p tcp -m tcp --dport 0:1023 --syn -j REJECT
-A RH-Lokkit-0-50-INPUT -p tcp -m tcp --dport 2049 --syn -j REJECT
-A RH-Lokkit-0-50-INPUT -p udp -m udp --dport 0:1023 -j REJECT
-A RH-Lokkit-0-50-INPUT -p udp -m udp --dport 2049 -j REJECT
-A RH-Lokkit-0-50-INPUT -p tcp -m tcp --dport 6000:6009 --syn -j REJECT
-A RH-Lokkit-0-50-INPUT -p tcp -m tcp --dport 7100 --syn -j REJECT
:INPUT DROP [16986:724916]
:OUTPUT DROP [409:31084]
:SERVICES - [0:0]
-A INPUT -d -i eth0 -m state --state RELATED,ESTABLISHED -j ACCEPT
-A INPUT -i lo -j ACCEPT
-A OUTPUT -s -o eth0 -j ACCEPT
-A OUTPUT -j LOG --log-prefix "[FILTER/OUTPUT] "
-A SERVICES -d -i eth0 -p tcp --dport 8000 -j ACCEPT
-A SERVICES -d -i eth0 -p tcp --dport 8001 -j ACCEPT
-A SERVICES -d -i eth0 -p tcp -m tcp --dport 22 -j ACCEPT

Despite the apparent settings in iptables, I still do not see ports 8000 and 8001 when I run "nmap -v" or "nmap -sT". Here's what it shows:

Starting nmap V. 3.00 ( )
No tcp,udp, or ICMP scantype specified, assuming SYN Stealth scan. Use -sP if you really don't want to portscan (and just want to see what hosts are up).
Host ( appears to be up ... good.
Initiating SYN Stealth Scan against (
Adding open port 6000/tcp
Adding open port 111/tcp
Adding open port 22/tcp
The SYN Stealth Scan took 2 seconds to scan 1601 ports.
Interesting ports on (
(The 1598 ports scanned but not shown below are in state: closed)
Port State Service
22/tcp open ssh
111/tcp open sunrpc
6000/tcp open X11

And here's what the SC server tells me:

** SHOUTcast Distributed Network Audio Server
** Copyright (C) 1998-2004 Nullsoft, Inc. All Rights Reserved.
** Use "sc_serv filename.ini" to specify an ini file.

Event log:
<05/16/04@17:33:42> [SHOUTcast] DNAS/Linux v1.9.4 (Mar 17 2004) starting up...
<05/16/04@17:33:42> [main] pid: 17423
<05/16/04@17:33:42> [main] loaded config from sc_serv.conf
<05/16/04@17:33:42> [main] initializing (usermax:100 portbase:8000)...
<05/16/04@17:33:42> [main] No ban file found (sc_serv.ban)
<05/16/04@17:33:42> [main] No rip file found (
<05/16/04@17:33:42> [main] relay thread starting
<05/16/04@17:33:42> [source] creating relay socket
<05/16/04@17:33:42> [main] opening client socket
<05/16/04@17:33:42> [main] Client Stream thread [0] starting
<05/16/04@17:33:42> [main] client main thread starting
<05/16/04@17:33:42> [source] relay host gave success (ICY 200 OK)
<05/16/04@17:33:42> [source] relay from established.
<05/16/04@17:33:42> [source] icy-name:RADIO MACONDO: Pura Salsa, Puro Son...El Canal Salsero de ORSRADIO ; icy-genre:World Latin Salsa
<05/16/04@17:33:42> [source] icy-pub:1 ; icy-br:96 ; icy-url:
<05/16/04@17:33:42> [source] icy-irc:N/A ; icy-icq:N/A ; icy-aim:N/A
<05/16/04@17:33:54> [yp_add] gave error (nak)
<05/16/04@17:33:54> [yp_add] gave extended error (Cannot see your station/computer (IP: from the Internet, disable Internet Sharing/NAT/firewall/ISP cache (Connection timed out))

Is there anything else I can do to open these ports?

Last edited by jslmg; 05-16-2004 at 04:12 AM.
Old 05-16-2004, 09:00 AM   #2
Registered: Apr 2004
Distribution: Ubuntu 7.10
Posts: 31

Original Poster
Rep: Reputation: 15

I ran "netstat -ant | grep LISTEN" and saw LISTEN

Still getting the error on the SC server, though.
Old 06-15-2004, 07:26 PM   #3
Registered: May 2004
Location: Orlando, Florida
Distribution: SLES10/11, RH4/5 svrs, Fedora, Debian/Ubuntu/Mint; FreeBSD/OpenBSD
Posts: 63

Rep: Reputation: 26
You need output rules, all you have is input rules. IE. when your svr broadcasts a stream, the listener will request more packets with a destination port of your server IP:8000. Setup a packet capture on the linux box, I used tcpdump. For windows, install Ethereal. Then run a packet capture and you will see that while traffic leaves your svr via port 8000, it also comes back in the same port. I had the same problem you had until I created an output rule for 8000. I found netstat and nmap unhelpful as they may show ports that are "open" or listening, but it means nothing if the actual traffic gets blocked.

Here is my iptables script. Notice the TOS rule that basically sts to give the outbound shoutcast traffic priority over other outbound traffic. Enjoy.

# Anti-spoof
for f in /proc/sys/net/ipv4/conf/*/rp_filter; do echo 1 > $f; done
# Policies (default)
iptables -P INPUT DROP
iptables -P FORWARD DROP
iptables -F INPUT
iptables -F FORWARD
iptables -F OUTPUT
# Rules for incoming packets from local interface
iptables -A INPUT -i lo -j ACCEPT
#Rules for incoming packets from the internet
# Packets for established connections
iptables -A INPUT -p ALL -d -m state --state ESTABLISHED,RELATED -j ACCEPT
iptables -A OUTPUT -t mangle -p tcp --sport 8000 -j TOS --set-tos Maximize-Throughput
#Rules for TCP/UDP packets
iptables -A INPUT -p tcp -m tcp -s 0/0 -d --dport 22 --syn -j ACCEPT
iptables -A INPUT -p tcp -m tcp -s 0/0 -d --dport 22 -j ACCEPT
iptables -A INPUT -p tcp -m tcp -s 0/0 --dport 8000 --syn -j ACCEPT
iptables -A INPUT -p tcp -m tcp -s 0/0 --dport 8000 -j ACCEPT
iptables -A INPUT -p udp -m udp -s 0/0 --sport 67:68 -d 0/0 --dport 67:68 -i eth0 -j ACCEPT
iptables -A INPUT -p udp -m udp -s --sport 53 -d 0/0 -j ACCEPT
iptables -A INPUT -p udp -m udp -s --sport 53 -d 0/0 -j ACCEPT
Old 07-13-2004, 11:06 AM   #4
Senior Member
Registered: Jun 2004
Location: Chicago
Distribution: Slackware64 -current
Posts: 1,158

Rep: Reputation: 61
Hi guys,
Can you look at this link and help me out here...seems you guys know about shoutcast and its config...
and yes...i can run shoutcast under windows (dual boot windows/RH9) pretty well so i'm doing something wrong under linux.

Thanks in advance.
Old 07-13-2004, 11:08 AM   #5
Senior Member
Registered: Jun 2004
Location: Chicago
Distribution: Slackware64 -current
Posts: 1,158

Rep: Reputation: 61
sorry broken link in the earlier post...
here's the link


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