So, I have a DigitalOcean droplet with key-based authentication over SSH. However, if I am connected to a specific WiFi network, the connection hangs indefinitely while connecting to the server. If I use any other WiFi network, including my phone's access point, it works normally. I'm using OpenSSH_8.6p1, OpenSSL 1.1.1k.
Running ssh user@server -vvv produces the following output:
OpenSSH_8.6p1, OpenSSL 1.1.1k FIPS 25 Mar 2021
debug1: Reading configuration data /etc/ssh/ssh_config
debug3: /etc/ssh/ssh_config line 55: Including file /etc/ssh/ssh_config.d/50-redhat.conf depth 0
debug1: Reading configuration data /etc/ssh/ssh_config.d/50-redhat.conf
debug2: checking match for 'final all' host server originally server
debug3: /etc/ssh/ssh_config.d/50-redhat.conf line 3: not matched 'final'
debug2: match not found
debug3: /etc/ssh/ssh_config.d/50-redhat.conf line 5: Including file /etc/crypto-policies/back-ends/openssh.config depth 1 (parse only)
debug1: Reading configuration data /etc/crypto-policies/back-ends/openssh.config
debug3: gss kex names ok: [gss-curve25519-sha256-,gss-nistp256-sha256-,gss-group14-sha256-,gss-group16-sha512-,gss-gex-sha1-,gss-group14-sha1-,gss-group1-sha1-]
debug3: kex names ok: [curve25519-sha256,[email protected],ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group14-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1]
debug1: configuration requests final Match pass
debug2: resolve_canonicalize: hostname server is address
debug1: re-parsing configuration
debug1: Reading configuration data /etc/ssh/ssh_config
debug3: /etc/ssh/ssh_config line 55: Including file /etc/ssh/ssh_config.d/50-redhat.conf depth 0
debug1: Reading configuration data /etc/ssh/ssh_config.d/50-redhat.conf
debug2: checking match for 'final all' host server originally server
debug3: /etc/ssh/ssh_config.d/50-redhat.conf line 3: matched 'final'
debug2: match found
debug3: /etc/ssh/ssh_config.d/50-redhat.conf line 5: Including file /etc/crypto-policies/back-ends/openssh.config depth 1
debug1: Reading configuration data /etc/crypto-policies/back-ends/openssh.config
debug3: gss kex names ok: [gss-curve25519-sha256-,gss-nistp256-sha256-,gss-group14-sha256-,gss-group16-sha512-,gss-gex-sha1-,gss-group14-sha1-,gss-group1-sha1-]
debug3: kex names ok: [curve25519-sha256,[email protected],ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group14-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1]
debug3: expanded UserKnownHostsFile '~/.ssh/known_hosts' -> '/home/user/.ssh/known_hosts'
debug3: expanded UserKnownHostsFile '~/.ssh/known_hosts2' -> '/home/user/.ssh/known_hosts2'
debug3: ssh_connect_direct: entering
debug1: Connecting to server [server] port 22.
debug3: set_sock_tos: set socket 4 IP_TOS 0x48
Checking if the port is blocked or if it fails on any other server, we can see that this is not the case:
ssh -T [email protected]
Hi User! You've successfully authenticated, but GitHub does not provide shell access
The contents on the server of /etc/sshd_config are:
Include /etc/ssh/sshd_config.d/*.conf
PasswordAuthentication no
And the contents on the server of /etc/ssh/sshd_config.d/50-redhat.conf (the only file in /etc/ssh/sshd_config.d) are:
Include /etc/crypto-policies/back-ends/opensshserver.config
SyslogFacility AUTHPRIV
ChallengeResponseAuthentication no
GSSAPIAuthentication yes
GSSAPICleanupCredentials no
UsePAM yes
X11Forwarding yes
PrintMotd no
AcceptEnv LANG LC_CTYPE LC_NUMERIC LC_TIME LC_COLLATE LC_MONETARY LC_MESSAGES
AcceptEnv LC_PAPER LC_NAME LC_ADDRESS LC_TELEPHONE LC_MEASUREMENT
AcceptEnv LC_IDENTIFICATION LC_ALL LANGUAGE
AcceptEnv XMODIFIERS
If I attempt to connect on any port (even if SSH is not enabled on that port on the server), the same result occurs: it hangs indefinitely.
I've tried clearing the entries for the server from ~/.ssh/known_hosts and ~/.ssh/known_hosts2, but nothing works. Is there any explanation for this?
/etc/hostsalaxxx.xxx.xxx.xxx fooit works withssh root@foo, but this is clearly not a solution :)