System:
$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 20.04.6 LTS
Release: 20.04
Codename: focal
Openssh version:
$ ssh -V
OpenSSH_8.2p1 Ubuntu-4ubuntu0.9, OpenSSL 1.1.1f 31 Mar 2020
Problem:
I'm trying to set up SSH so I can access it over WAN (i.e. Internet). It works no problem over LAN:
% ssh 10.81.1.222 -p 22
Enter passphrase for key '/Users/userid/.ssh/id_rsa':
However it fails when I try over WAN. I'm using a Linksys Velop mesh router. I have confirmed:
- Port 22 on my router is forwarded to port 22 on my server @10.81.1.222
- My external IP address using https://api.ipify.org/
- ufw is inactive using "sudo ufw status"
- server @10.81.1.222 has an Internet connection (I can ping cnn.com)
I have tried two different Internet providers: my Android phone as a hotspot and Xfinity. The latter times out (I've read others have had problems recently using ssh w/ Xfinity), the former leads to connection refused. My ISP is AT&T.
Xfinity:
% ssh -v my_userid@###.###.###.### -p 22
OpenSSH_8.6p1, LibreSSL 3.3.6
debug1: Reading configuration data /Users/my_userid/.ssh/config
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 21: include /etc/ssh/ssh_config.d/* matched no files
debug1: /etc/ssh/ssh_config line 54: Applying options for *
debug1: Authenticator provider $SSH_SK_PROVIDER did not resolve; disabling
debug1: Connecting to ###.###.###.### [###.###.###.###] port 22.
debug1: connect to address ###.###.###.### port 22: Operation timed out
ssh: connect to host ###.###.###.### port 22: Operation timed out
Android:
% ssh -v my_userid@###.###.###.### -p 22
OpenSSH_8.6p1, LibreSSL 3.3.6
debug1: Reading configuration data /Users/my_userid/.ssh/config
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 21: include /etc/ssh/ssh_config.d/* matched no files
debug1: /etc/ssh/ssh_config line 54: Applying options for *
debug1: Authenticator provider $SSH_SK_PROVIDER did not resolve; disabling
debug1: Connecting to ###.###.###.### [###.###.###.###] port 22.
debug1: connect to address ###.###.###.### port 22: Connection refused
ssh: connect to host ###.###.###.### port 22: Connection refused
Note:
While connected to Android, my phone was still connected to my router, so this continued to work:
% ssh 10.81.1.222 -p 22
While connected to Xfinity and after disconnecting my phone from my router, pinging the external IP address failed:
% ping ###.###.###.###
PING ###.###.###.### (###.###.###.###): 56 data bytes
Request timeout for icmp_seq 0
Request timeout for icmp_seq 1
Request timeout for icmp_seq 2
Any suggestions?
I purged openssh and reinstalled while troubleshooting, so I'm currently using the default sshd_config, but I've pasted it here for completness.
# $OpenBSD: sshd_config,v 1.103 2018/04/09 20:41:22 tj Exp $
# This is the sshd server system-wide configuration file. See
# sshd_config(5) for more information.
# This sshd was compiled with PATH=/usr/bin:/bin:/usr/sbin:/sbin
# The strategy used for options in the default sshd_config shipped with
# OpenSSH is to specify options with their default value where
# possible, but leave them commented. Uncommented options override the
# default value.
Include /etc/ssh/sshd_config.d/*.conf
#Port 22
#AddressFamily any
#ListenAddress 0.0.0.0
#ListenAddress ::
#HostKey /etc/ssh/ssh_host_rsa_key
#HostKey /etc/ssh/ssh_host_ecdsa_key
#HostKey /etc/ssh/ssh_host_ed25519_key
# Ciphers and keying
#RekeyLimit default none
# Logging
#SyslogFacility AUTH
#LogLevel INFO
# Authentication:
#LoginGraceTime 2m
#PermitRootLogin prohibit-password
#StrictModes yes
#MaxAuthTries 6
#MaxSessions 10
#PubkeyAuthentication yes
# Expect .ssh/authorized_keys2 to be disregarded by default in future.
#AuthorizedKeysFile .ssh/authorized_keys .ssh/authorized_keys2
#AuthorizedPrincipalsFile none
#AuthorizedKeysCommand none
#AuthorizedKeysCommandUser nobody
# For this to work you will also need host keys in /etc/ssh/ssh_known_hosts
#HostbasedAuthentication no
# Change to yes if you don't trust ~/.ssh/known_hosts for
# HostbasedAuthentication
#IgnoreUserKnownHosts no
# Don't read the user's ~/.rhosts and ~/.shosts files
#IgnoreRhosts yes
# To disable tunneled clear text passwords, change to no here!
#PasswordAuthentication yes
#PermitEmptyPasswords no
# Change to yes to enable challenge-response passwords (beware issues with
# some PAM modules and threads)
ChallengeResponseAuthentication no
# Kerberos options
#KerberosAuthentication no
#KerberosOrLocalPasswd yes
#KerberosTicketCleanup yes
#KerberosGetAFSToken no
# GSSAPI options
#GSSAPIAuthentication no
#GSSAPICleanupCredentials yes
#GSSAPIStrictAcceptorCheck yes
#GSSAPIKeyExchange no
# Set this to 'yes' to enable PAM authentication, account processing,
# and session processing. If this is enabled, PAM authentication will
# be allowed through the ChallengeResponseAuthentication and
# PasswordAuthentication. Depending on your PAM configuration,
# PAM authentication via ChallengeResponseAuthentication may bypass
# the setting of "PermitRootLogin without-password".
# If you just want the PAM account and session checks to run without
# PAM authentication, then enable this but set PasswordAuthentication
# and ChallengeResponseAuthentication to 'no'.
UsePAM yes
#AllowAgentForwarding yes
#AllowTcpForwarding yes
#GatewayPorts no
X11Forwarding yes
#X11DisplayOffset 10
#X11UseLocalhost yes
#PermitTTY yes
PrintMotd no
#PrintLastLog yes
#TCPKeepAlive yes
#PermitUserEnvironment no
#Compression delayed
#ClientAliveInterval 0
#ClientAliveCountMax 3
#UseDNS no
#PidFile /var/run/sshd.pid
#MaxStartups 10:30:100
#PermitTunnel no
#ChrootDirectory none
#VersionAddendum none
# no default banner path
#Banner none
# Allow client to pass locale environment variables
AcceptEnv LANG LC_*
# override default of no subsystems
Subsystem sftp /usr/lib/openssh/sftp-server
# Example of overriding settings on a per-user basis
#Match User anoncvs
# X11Forwarding no
# AllowTcpForwarding no
# PermitTTY no
# ForceCommand cvs server
