I have a AST2600 evb board. After power on (w/ RJ45 connected), it boots into a OpenBMC kernel. From serial port, using ip command I can obtain its IP address. From my laptop, I can ssh into the board using account root/0penBmc:
bruin#gen81:/$ ssh root#192.168.6.132
root#192.168.6.132's password:
Then I want to find out which tcp ports are open. As there is no ss/lsof/netstat utilities, I cat /proc/net/tcp:
root#AMIfa7ba648f62e:/proc/net# cat /proc/net/tcp
sl local_address rem_address st tx_queue rx_queue tr tm->when retrnsmt uid timeout inode
0: 00000000:14EB 00000000:0000 0A 00000000:00000000 00:00000000 00000000 997 0 9565 1 0c202562 100 0 0 10 0
1: 3500007F:0035 00000000:0000 0A 00000000:00000000 00:00000000 00000000 997 0 9571 1 963c8114 100 0 0 10 0
The strange thing puzzled me is that that tcp port 22 is not listed in /proc/net/tcp, which suggests that no process is listening on tcp port 22. If this is true, how the ssh connection is established?
Btw, as tested using ps, it's the dropbear process who is handling the ssh connection, and the dropbear is spawned dynamically (i.e., if no ssh connection, no such process exist; if I made two ssh connection, two dropbear processes were spawned).
PS: as suggested by John in his reply, I added the ss utilities into the image, and it shows what I expected:
root#AMI8287361b9c6f:~# ss -antp
State Recv-Q Send-Q Local Address:Port Peer Address:Port
LISTEN 0 0 0.0.0.0:5355 0.0.0.0:* users:(("systemd-resolve",pid=239,fd=12))
LISTEN 0 0 127.0.0.1:5900 0.0.0.0:* users:(("obmc-ikvm",pid=314,fd=5))
LISTEN 0 0 127.0.0.53:53 0.0.0.0:* users:(("systemd-resolve",pid=239,fd=17))
LISTEN 0 0 *:443 *:* users:(("bmcweb",pid=325,fd=3),("systemd",pid=1,fd=41))
LISTEN 0 0 *:5355 *:* users:(("systemd-resolve",pid=239,fd=14))
LISTEN 0 0 *:5900 *:* users:(("obmc-ikvm",pid=314,fd=6))
LISTEN 0 0 *:22 *:* users:(("systemd",pid=1,fd=49))
LISTEN 0 0 *:2200 *:* users:(("systemd",pid=1,fd=50))
ESTAB 0 0 [::ffff:192.168.6.89]:22 [::ffff:192.168.6.98]:34906 users:(("dropbear",pid=485,fd=2),("dropbear",pid=485,fd=1),("dropbear",pid=485,fd=0),("systemd",pid=1,fd=20))
Good question.
First, it is pretty straigt forward to add common tools/utitlies to an image.
It could be added (for local testing only) by adding a line
OBMC_IMAGE_EXTRA_INSTALL:append = " iproute2 iproute2-ss"
to the https://github.com/openbmc/openbmc/blob/master/meta-aspeed/conf/machine/evb-ast2600.conf file (or to your own testing/deveopment layer). Adding useful tools is often worth it.
Second, if you are using ipv6 you will need to check /proc/net/tcp6
Third, you can also look for a port by looking up the pid of your application ps | grep <application name>. Then reading the port used by that pid cat /proc/<pid>/net/tcp
Last, if you have any more question or these steps don't work. Please reach out to us on discord https://discord.com/invite/69Km47zH98 or Email https://lists.ozlabs.org/listinfo/openbmc (they are the preferred place to ask questions)
I launched a program that listens at 127.0.0.1:3000 on a CentOS server. I haven't sent any message to the program but it keeps receiving data. I want to know who is sending data to my program. So I type in the following command:
netstat -an | grep 3000
A snapshot output is:
tcp 0 0 127.0.0.1:3000 0.0.0.0:* LISTEN
tcp 0 0 127.0.0.1:3000 127.0.0.1:41960 TIME_WAIT
tcp 0 0 127.0.0.1:3000 127.0.0.1:41956 TIME_WAIT
tcp 0 0 127.0.0.1:3000 127.0.0.1:41964 TIME_WAIT
tcp 1 0 127.0.0.1:41968 127.0.0.1:3000 CLOSE_WAIT
tcp 0 0 127.0.0.1:3000 127.0.0.1:41952 TIME_WAIT
tcp 0 0 127.0.0.1:3000 127.0.0.1:41968 FIN_WAIT2
The output changes every time I type in the command. The port numbers in a pattern like 4xxxx increment frequently.
If I type in lsof -nPi tcp:3000, one of the outputs is
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
node 76230 xxx 18u IPv4 130828 0t0 TCP 127.0.0.1:3000 (LISTEN)
node 76230 xxx 20u IPv4 208468 0t0 TCP 127.0.0.1:3000->127.0.0.1:42072 (ESTABLISHED)
I don't know what these 4xxxx numbers stand for. In my case, how to know who is sending data to 127.0.0.1:3000?
You got a PID 76230 and having that you can get to know the process name by
$ ps -p 76230 -o comm=
I have a VM in which I installed the VNC server (TightVNC) using the link : https://www.digitalocean.com/community/tutorials/how-to-install-and-configure-vnc-on-ubuntu-18-04
It is installed successfully and I can see the port 5901 running
/etc/tigervnc$ netstat -tulpn
(Not all processes could be identified, non-owned process info
will not be shown, you would have to be root to see it all.)
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name
tcp 0 0 127.0.0.1:5901 0.0.0.0:* LISTEN 16460/Xtigervnc
tcp 0 0 127.0.0.1:5902 0.0.0.0:* LISTEN 16183/Xtigervnc
tcp 0 0 127.0.0.53:53 0.0.0.0:* LISTEN -
tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN -
tcp 0 0 127.0.0.1:631 0.0.0.0:* LISTEN -
tcp6 0 0 ::1:5901 :::* LISTEN 16460/Xtigervnc
tcp6 0 0 ::1:5902 :::* LISTEN 16183/Xtigervnc
tcp6 0 0 :::22 :::* LISTEN -
tcp6 0 0 ::1:631 :::* LISTEN -
udp 0 0 0.0.0.0:36618 0.0.0.0:* -
udp 29184 0 127.0.0.53:53 0.0.0.0:* -
udp 0 0 0.0.0.0:68 0.0.0.0:* -
udp 0 0 0.0.0.0:631 0.0.0.0:* -
udp 7680 0 0.0.0.0:5353 0.0.0.0:* -
udp6 0 0 :::37372 :::* -
udp6 20736 0 :::5353 :::*
Now from my local machine, I tried to do the port binding to my local from VM (as per the link https://www.digitalocean.com/community/tutorials/how-to-install-and-configure-vnc-on-ubuntu-18-04)
ssh -L 5901:127.0.0.1:5901 -C -N -l test 172.1.1.1
In my local machine, I able to see the port is binded to 5901
/etc/guacamole$ fuser 5901/tcp
5901/tcp: 22049
Now when I try to take the VNC connection using 127.0.0.1:5901, It promopts for VM's password and shows only the blank page.
Could someone help me with this?
Thanks,
Hari
edit your ~/.vnc/xstartup file thus:
#!/bin/sh
startxfce4 &
I had the same problem and this solved it
For reference i got it from here:
https://www.raspberrypi.org/forums/viewtopic.php?t=52557
You can also try killing and restarting your VNC server
kill $(pgrep Xvnc)
vncserver
Are you trying to VNC from the local machine to the local machine? I am assuming just for testing correct?
If you are not getting a rejection, at least it should be talking to the service.
I'm tryign to telnet from one linux env (10.205.116.141) to 10.205.117.246 on port 7199 but keep getting a connection refused. I did a chkconfig iptables off on both servers and even make sure iptables if stopped as well.
what else should I be looking at?
[root#ip-10-205-116-141 bin]# telnet 10.205.117.246 7199
Trying 10.205.117.246...
telnet: connect to address 10.205.117.246: Connection refused
trace route seems to be working as well...
[root#ip-10-205-116-141 bin]# traceroute 10.205.117.246 -p 7199
traceroute to 10.205.117.246 (10.205.117.246), 30 hops max, 60 byte packets
1 ip-10-205-117-246.xyz.cxcvs.com (10.205.117.246) 0.416 ms 0.440 ms 0.444 ms
also, I'm on a aws vpc so we don't get public IPs provisioned for use...
checked my security group and it looks like all ports are open as well
EDIT:
here is netstat as well, they look the same on both nodes:
[ec2-user#ip-10-205-116-141 ~]$ netstat -an | grep LISTEN
tcp 0 0 127.0.0.1:46626 0.0.0.0:* LISTEN
tcp 0 0 127.0.0.1:9160 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:36523 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:111 0.0.0.0:* LISTEN
tcp 0 0 127.0.0.1:9042 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:2738 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN
tcp 0 0 10.205.116.141:7000 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:8089 0.0.0.0:* LISTEN
tcp 0 0 127.0.0.1:25 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:4445 0.0.0.0:* LISTEN
tcp 0 0 127.0.0.1:7199 0.0.0.0:* LISTEN
shouldn't 127.0.0.1:7199 really be 10.205.116.141:7199?
sorry, can't post a sc of the security groups...
developer#LinuxKernel:~> sudo netstat -elnopt
developer's password:
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address Foreign Address State User Inode PID/Program name Timer
tcp 0 0 0.0.0.0:10080 0.0.0.0:* LISTEN 1003 3061421021 - off (0.00/0/0)
Regarding my experience, I have the authority to check the PID/Program name of netstat with sudo, how to explain this one, the kernel is 2.6.16.60, net-tools 1.6, netstat 1.42
A dash "-" is given when the kernel itself is listening, consequently there are no associated processes to show. I am not sure which kernel thread is using tcp/10080 though.