Hello all. I’m trying to change the SSH port on an Oracle VM, but I’m getting nowhere and I don’t know where to solve the issue.
I have changed the SSH port:
edit /etc/ssh/sshd_config
Entered the port info:
Port 5522
I restarted the service:
sudo systemctl restart ssh
And made sure that the port is open:
ss -an | grep 5522
tcp LISTEN 0 128 0.0.0.0:5522 0.0.0.0:*
tcp LISTEN 0 128 [::]:5522 [::]:*
I also allow incoming traffic to 5522:
sudo ufw allow 22/tcp comment 'Open port ssh tcp port 22'
AND just to make sure, I allow ‘routed’:
sudo ufw default allow FORWARD
And make sure the FW config is valid:
sudo ufw status verbose
Status: active
Logging: on (medium)
Default: deny (incoming), allow (outgoing), allow (routed)
New profiles: skip
To Action From
-- ------ ----
22/tcp ALLOW IN Anywhere # Open port ssh tcp port 22
5522/tcp ALLOW IN Anywhere
22/tcp (v6) ALLOW IN Anywhere (v6) # Open port ssh tcp port 22
5522/tcp (v6) ALLOW IN Anywhere (v6) # Open real ssh tcp port 22
Yet, I cannot connect to this server. Trying to ssh -vvvv -p 5522 [ip-adress] yields this:
OpenSSH_9.0p1 Ubuntu-1ubuntu8.4, OpenSSL 3.0.8 7 Feb 2023
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 19: include /etc/ssh/ssh_config.d/*.conf matched no files
debug1: /etc/ssh/ssh_config line 21: Applying options for *
debug2: resolve_canonicalize: hostname 129.x.x.5 is address
debug3: expanded UserKnownHostsFile '~/.ssh/known_hosts' -> '/home/x/.ssh/known_hosts'
debug3: expanded UserKnownHostsFile '~/.ssh/known_hosts2' -> '/home/x/.ssh/known_hosts2'
debug3: ssh_connect_direct: entering
debug1: Connecting to 129.x.x.5 [129.x.x.5] port 5522.
debug3: set_sock_tos: set socket 3 IP_TOS 0x10
debug1: connect to address 129.x.x.5 port 5522: No route to host
ssh: connect to host 129.x.x.5 port 5522: No route to host
I can connect just fine when the port is at 22, but as soon as I change it to 5522, i get the ‘no route to host’ error.
I’ve made sure I have rules on Oracle cloud that allows ingress and egress traffic to 0.0.0.0/24 on all protocols, no matter the destination / source.
What am I doing wrong? It feels that this problem is host (server) based rather client based, since I’m getting a routing error. Do I need to configure the routing for that port specifically, and if so how?
PS: Also, connecting to localhost:5522 from the server itself works fine. So the problem is not in the configuration, but likely network related.
Ist that
0.0.0.0/24CIDR a typo? That suffix should probably be/0.Also make sure to actually assign the firewall to your instance’s subnet in the Oracle cloud Interface.
Correct - that was a typo, I’ve corrected the original post. Not a good idea to write a report when you’re angry and tired… 🤣
The firewall (Network Security Group in Oracle lingo) is indeed attached to the subnet. I think I’ve solved the issue, will write it in a seperate post and link it to the original post.
ufw allow 22/tcp comment ‘Open port ssh tcp port 22’
is this a typo or is port 5522 actually not open on your firewall?
Correct - that was a typo in this post. The output from
sudo ufw status verboseis however correct.I think I’ve solved the issue, will write it in a seperate post and link it to the original post.
Do you have a firewall between the two devices?
Can you do a packet capture to make sure that both ends are behaving as expected?
Can you double check your IPs. I’ve had this issue before by fat fingering
So I managed to smash a few buttons randomly again, and get this solved.
There are a few things to be aware of:
- Oracle doesn’t like ufw. So I disabled it and uninstalled it. Having ufw installed may result in bad stuff. Link
- I decided to flush all rules in ip-tables to start on a clean slate:
sudo iptables -F - While I’m at it, I’ve changed ip-tables to allow ALL. THE. INBOUND. TRAFFIC:
sudo iptables -I INPUT -j ACCEPT - One last thing, I’ve changed the state of the firewall to go from stateful to stateless, still with no restrictions on the ingress / egress traffic.
This is, of course, not a recommended setup for a host to be used in production or to have critical data, but it gave me a host in a working state that I can work with.
Some posts that helped me in this:
