Notes to self, 2024

2024-04-17 - mariadb check table / galera locking

After upgrading some database nodes from MariaDB 10.3 to 10.6 we encountered some issues with tables not being fully correct. We'd like to CHECK TABLE the entire database. But the database must not block queries on other nodes of the cluster.

The corruption we saw might have been a small corruption that has crept in even earlier upgrades, we don't know. But we do know that we'd like to get this sorted before the corruption gets worse after further upgrades.

The requirement that the “show must go on” is obvious. Because we always have three nodes in a cluster, we can safely take one out and do table checks and repairs on a single one.

But, it has to be back in the cluster in time to still get an IST. If it is so far out of sync that it has to do an SST, the whole exercise is pointless. (Okay — not entirely pointless — we might see the corruption, but we won't have fixed it.)

The following helper script makes repairing/checking easier by running a single CHECK TABLE and then waiting for the node to catch up before doing the next table.

The special spice in this script is wsrep_desync=ON. Without it the node would still accept wsrep updates and block. A DDL statement like ALTER TABLE does not require it, but CHECK TABLE does.

With a small adaptation, you could use this script to ALTER TABLE FORCE instead. A lengthier operation that allows you to reclaim space as well. This optional change is left to the reader.

#!/bin/sh
#
# This script does a CHECK TABLE on all tables of a MariaDB server,
# but it waits for the node to catch up (Sync) after each table.
#
# When a MariaDB server is part of a Galera cluster, it is allowed
# to go out-of-sync -- assuming you ensure that regular clients are
# disallowed access during this time.
#
# But if you run a CHECK TABLE, it LOCKs by default, instead of going
# out-of-sync. The wsrep_OSU_method=RSU + wsrep_desync=ON settings
# here make sure that the other nodes in the Galera cluster can
# continue operating.
#
# Usage:
#
#   mariadb-galera-check-all-tables 2>&1 | tee output.log
#
# It will write a mariadb-galera-check-all-tables.table_cache file,
# iterate over it, CHECK TABLE for each table, and wait for it to
# go back to synced state.
#
# Afterwards you can check the log for issues found and repairs done.
# 
# (ossobv/2024-04-17)

# Statements to allow us to go out of sync.
BEGIN_WORK='SET SESSION wsrep_OSU_method=RSU; SET GLOBAL wsrep_desync=ON'
END_WORK='SET SESSION wsrep_OSU_method=TOI; SET GLOBAL wsrep_desync=OFF'

sql() {
    # If needed, you can add appropriate auth flags here.
    mysql -NBe "$1"
}

when() {
    date --rfc-3339=seconds
}

# Get tables into a file, use get_tables() to get them.
make_tables() {
    # Repairing appears to work fine on:
    # - InnoDB, MyISAM, Aria, CSV
    # Not fine on:
    # - PERFORMANCE_SCHEMA (storage engine doesn't support check)
    sql '
        SELECT CONCAT("`", table_schema, "`.`", table_name, "`") as tbl
        FROM information_schema.tables
        WHERE table_type = '\''BASE TABLE'\''
          AND engine NOT IN ('\''PERFORMANCE_SCHEMA'\'')
        ORDER BY table_schema, table_name;' \
      >"$0.table_cache"
}

# Use intermediate function, in case you want to alter the tables
# or manually set them.
get_tables() {
    cat "$0.table_cache"
}

check_table() {
    local table="$1"
    echo -n "$(when): CHECK TABLE $table ... "
    # Do a CHECK TABLE + ANALYZE TABLE for good measure.
    local work="CHECK TABLE $table; ANALYZE TABLE $table"
    # Wrapped in $() to collapse whitespace/linefeeds.
    echo $(sql "$BEGIN_WORK; $work; $END_WORK;")
}

# Check galera Write Set REPlication status;
# return OK when in Sync or ERROR if not.
galera_is_in_sync() {
    sql "SHOW STATUS LIKE 'wsrep_local_state_comment';" |
      grep -q '[[:blank:]]Synced$'
}


# Make tables (comment if you're editing the tables file)
make_tables
#exit  # uncomment to just produce the tables file

# Make sure the server can go back to Synced state
# (might be invoked twice, but it's idempotent)
trap 'sql "$END_WORK;"; echo; echo "$(when): $END_WORK"' EXIT INT

# Loop over tables from the cache file
get_tables | while read -r table; do
    check_table "$table" || break
    while ! galera_is_in_sync; do
        echo "$(when): (not in sync yet)"
        sleep 10 || break
    done
done

Run this for each MariaDB node in your Galera cluster, one at a time, while they are not taking client connections.

2024-03-29 - systemd-networkd-wait-online / stalling and failing

systemd-networkd-wait-online.service failing? Maybe it's IPv6.

Do you have a list of failed systemd units that looks like this?

# systemctl list-units --failed
  UNIT                                 LOAD   ACTIVE SUB    DESCRIPTION                      
‚óŹ systemd-networkd-wait-online.service loaded failed failed Wait for Network to be Configured

Then that could be due to IPv6 networking not being set up properly.

Check the interfaces list:

# ip -br a
lo               UNKNOWN        127.0.0.1/8 ::1/128 
ens18            UP             10.20.30.41/31 fe80::a124:092f:fa18:109e/64 
ens19            UP             192.168.1.3/31 fe80::a124:092f:fa15:01d5/64 

Proper IPv4 IPs, and only link-local IPs for IPv6? Likely you're not using IPv6 at all here.

The logs have this to say:

# journalctl -u systemd-networkd*service
14:25:58 systemd[1]: Starting Network Configuration...
14:25:58 systemd-networkd[1728946]: ens19: Link UP
14:25:58 systemd-networkd[1728946]: ens19: Gained carrier
14:25:58 systemd-networkd[1728946]: ens18: Link UP
14:25:58 systemd-networkd[1728946]: ens18: Gained carrier
14:25:58 systemd-networkd[1728946]: lo: Link UP
14:25:58 systemd-networkd[1728946]: lo: Gained carrier
14:25:58 systemd-networkd[1728946]: ens19: Gained IPv6LL
14:25:58 systemd-networkd[1728946]: ens18: Gained IPv6LL
14:25:58 systemd-networkd[1728946]: Enumeration completed
14:25:58 systemd[1]: Started Network Configuration.
14:25:58 systemd[1]: Starting Wait for Network to be Configured...
14:27:58 systemd-networkd-wait-online[1728947]: Timeout occurred while waiting for network connectivity.
14:27:58 systemd[1]: systemd-networkd-wait-online.service: Main process exited, code=exited, status=1/FAILURE
14:27:58 systemd[1]: systemd-networkd-wait-online.service: Failed with result 'exit-code'.
14:27:58 systemd[1]: Failed to start Wait for Network to be Configured.
14:41:05 systemd-networkd[1728946]: ens19: Re-configuring with /run/systemd/network/10-netplan-ens19.network
14:41:05 systemd-networkd[1728946]: ens19: DHCPv6 lease lost
14:41:05 systemd-networkd[1728946]: ens18: Re-configuring with /run/systemd/network/10-netplan-ens18.network
14:41:05 systemd-networkd[1728946]: ens18: DHCPv6 lease lost
14:41:05 systemd-networkd[1728946]: ens19: Re-configuring with /run/systemd/network/10-netplan-ens19.network
14:41:05 systemd-networkd[1728946]: ens19: DHCPv6 lease lost
14:41:05 systemd-networkd[1728946]: ens18: Re-configuring with /run/systemd/network/10-netplan-ens18.network
14:41:05 systemd-networkd[1728946]: ens18: DHCPv6 lease lost
14:41:12 systemd[1]: Starting Wait for Network to be Configured...
14:43:12 systemd-networkd-wait-online[1733339]: Timeout occurred while waiting for network connectivity.
14:43:12 systemd[1]: systemd-networkd-wait-online.service: Main process exited, code=exited, status=1/FAILURE
14:43:12 systemd[1]: systemd-networkd-wait-online.service: Failed with result 'exit-code'.
14:43:12 systemd[1]: Failed to start Wait for Network to be Configured.

What's in that 10-netplan-ens18.network?

# cat /run/systemd/network/10-netplan-ens18.network
[Match]
Name=ens18

[Network]
LinkLocalAddressing=ipv6
Address=10.20.30.41/31
DNS=1.1.1.1
DNS=8.8.8.8

[Route]
Destination=0.0.0.0/0
Gateway=10.20.30.40

Again, only IPv4 addresses.

Solution

Add link-local: [ipv4] to the interfaces in the Netplan configuration:

--- a/netplan/01-netcfg.yaml
+++ b/netplan/01-netcfg.yaml
@@ -11,9 +11,11 @@ network:
         addresses:
         - 1.1.1.1
         - 8.8.8.8
+      link-local: [ipv4]
     ens19:
       addresses:
       - 192.168.1.3/31
       routes:
       - to: 192.168.1.0/24
         via: 192.168.1.2
+      link-local: [ipv4]

Now run a netplan apply and observe:

# systemctl restart systemd-networkd-wait-online.service 

That succeeds immediately, like it should.

In 10-netplan-ens18.network (and the others), LinkLocalAddressing=ipv6 is now LinkLocalAddressing=ipv4.

And the logs also appear happier:

# journalctl -u systemd-networkd*service
14:54:46 systemd-networkd[1728946]: ens19: Re-configuring with /run/systemd/network/10-netplan-ens19.network
14:54:46 systemd-networkd[1728946]: ens19: DHCPv6 lease lost
14:54:46 systemd-networkd[1728946]: ens18: Re-configuring with /run/systemd/network/10-netplan-ens18.network
14:54:46 systemd-networkd[1728946]: ens18: DHCPv6 lease lost
14:54:46 systemd-networkd[1728946]: ens19: Re-configuring with /run/systemd/network/10-netplan-ens19.network
14:54:46 systemd-networkd[1728946]: ens18: Re-configuring with /run/systemd/network/10-netplan-ens18.network
14:54:52 systemd[1]: Starting Wait for Network to be Configured...
14:54:53 systemd[1]: Finished Wait for Network to be Configured.

2024-03-22 - nmap ssl-enum-ciphers / haproxy / tls / no results

When doing an nmap ssl-enum-ciphers scan on a Haproxy machine, I got zero working ciphers. But connecting with TLS worked just fine. What is up?

While updating TLS ciphers to disable certain unsafe ciphers, we wanted to test the current offers. nmap with the ssl-enum-ciphers should work fine for this, and it is reasonably fast:

$ nmap -Pn --script=ssl-enum-ciphers -p 443 google.com
...
443/tcp open  https
| ssl-enum-ciphers: 
|   TLSv1.0: 
...
|   TLSv1.1: 
...
|   TLSv1.2: 
|     ciphers: 
|       TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA (ecdh_x25519) - A
...
|     warnings: 
|       64-bit block cipher 3DES vulnerable to SWEET32 attack
|_  least strength: C

Nmap done: 1 IP address (1 host up) scanned in 1.27 seconds

Okay, that is convenient. On to the relevant host.

On the host, we've configured TLSv1.2 and TLSv1.3 with a limited set of ciphers. Let's go:

$ nmap -Pn --script=ssl-enum-ciphers -p 443 x.x.x.x
...
443/tcp open  https

Nothing?!

Apparently the nmap 7.91 scripts on Ubuntu/Jammy are a bit outdated and have no TLSv1.3 support. It was added in nmap commit 7c61f7c.

We can patch our Ubuntu/Jammy nmap with this adapted patch:
nmap-ssl-enum-ciphers-tls13-for-ubuntu-jammy.patch

$ cd /usr/share/nmap
$ sudo patch -p1 < /PATH/TO/nmap-ssl-enum-ciphers-tls13-for-ubuntu-jammy.patch

Let's try again:

$ nmap -Pn --script=ssl-enum-ciphers -p 443 $haproxy
...
443/tcp open  https
| ssl-enum-ciphers: 
|   TLSv1.3: 
|     ciphers: 
|       TLS_AKE_WITH_AES_128_GCM_SHA256 (ecdh_x25519) - A
|       TLS_AKE_WITH_AES_256_GCM_SHA384 (ecdh_x25519) - A
|       TLS_AKE_WITH_CHACHA20_POLY1305_SHA256 (ecdh_x25519) - A
|     cipher preference: client
|_  least strength: A

Nice! TLSv1.3 results. But where is the TLSv1.2?

We know that the script supports TLSv1.2, as seen with the google.com example above. In fact, rerunning it now shows that google.com also does TLSv1.3, as you'd expect.

The Haproxy config looks sane:

global
    # "server ciphers"
    ssl-default-bind-ciphers ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-ECDSA-CHACHA20-POLY1305
    ssl-default-bind-ciphersuites TLS_AES_256_GCM_SHA384:TLS_AES_128_GCM_SHA256:TLS_CHACHA20_POLY1305_SHA256
    ssl-default-bind-options prefer-client-ciphers no-tls-tickets ssl-min-ver TLSv1.2 ssl-max-ver TLSv1.3

And openssl s_client -no_tls1_3 -connect will happily connect with TLSv1.2.

If we try a kube-apiserver with the same set of ciphers configured, it does yield both TLSv1.2 and TLSv1.3:

# kube-apiserver [...] --tls-cipher-suites=\
TLS_AES_256_GCM_SHA384,TLS_AES_128_GCM_SHA256,TLS_CHACHA20_POLY1305_SHA256,\
TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384,TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256,TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256
$ nmap -Pn --script=ssl-enum-ciphers -p 443 $kube-apiserver
...
443/tcp open  https
| ssl-enum-ciphers: 
|   TLSv1.2: 
|     ciphers: 
|       TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256 - unknown
|       TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 - unknown
|       TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384 - unknown
|     compressors: 
|       NULL
|     cipher preference: server
|   TLSv1.3: 
|     ciphers: 
|       TLS_AKE_WITH_CHACHA20_POLY1305_SHA256 (ecdh_x25519) - A
|       TLS_AKE_WITH_AES_128_GCM_SHA256 (ecdh_x25519) - A
|       TLS_AKE_WITH_AES_256_GCM_SHA384 (ecdh_x25519) - A
|     cipher preference: server
|_  least strength: unknown

So, something is different with Haproxy.

The openssl s_client output did not give many clues, but there was one:

Client Certificate Types: RSA sign, ECDSA sign for the kube-apiserver and
Client Certificate Types: RSA sign, DSA sign, ECDSA sign for Haproxy.

And indeed, there is a related fix in nmap commit 034ea73.

Apply the following patch as well:
nmap-ssl-enum-ciphers-tls12-ecdsa-in-ubuntu-jammy.patch

$ cd /usr/share/nmap
$ sudo patch -p1 < /PATH/TO/nmap-ssl-enum-ciphers-tls12-ecdsa-in-ubuntu-jammy.patch

And now a rescan finally shows both TLS protocols on Haproxy as well.

$ nmap -Pn --script=ssl-enum-ciphers -p 443 $haproxy
...
443/tcp open  https
| ssl-enum-ciphers: 
|   TLSv1.2: 
|     ciphers: 
|       TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 (secp256r1) - A
|       TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384 (secp256r1) - A
|       TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256 (secp256r1) - A
|     compressors: 
|       NULL
|     cipher preference: client
|   TLSv1.3: 
|     ciphers: 
|       TLS_AKE_WITH_AES_128_GCM_SHA256 (ecdh_x25519) - A
|       TLS_AKE_WITH_AES_256_GCM_SHA384 (ecdh_x25519) - A
|       TLS_AKE_WITH_CHACHA20_POLY1305_SHA256 (ecdh_x25519) - A
|     cipher preference: client
|_  least strength: A

(Aha! That unknown is now gone too.)

2024-01-23 - gpg-agent / ssh / ed25519 / agent refused

After putting in all the work to get ED25519 OpenPGP keys in my Yubikey smart card, I was slightly frustrated that the SSH support "sometimes" didn't work.

I thought I had tested that it worked, but today it didn't.

$ ssh my_server
sign_and_send_pubkey: signing failed for ED25519 "cardno:000612345678" from agent: agent refused operation
walter@my_server: Permission denied (publickey).

That's odd.

Adding some debug to the gpg-agentdebug 1024 in gpg-agent.conf — got me this:

DBG: chan_10 -> SERIALNO
DBG: chan_10 <- S SERIALNO D2760001240103040006123456780000
DBG: chan_10 <- OK
DBG: chan_10 -> GETINFO card_list
DBG: chan_10 <- S SERIALNO D2760001240103040006123456780000
DBG: chan_10 <- OK
DBG: chan_10 -> SERIALNO --demand=D2760001240103040006123456780000
DBG: chan_10 <- S SERIALNO D2760001240103040006123456780000
DBG: chan_10 <- OK
DBG: chan_10 -> GETATTR $AUTHKEYID
DBG: chan_10 <- S $AUTHKEYID OPENPGP.3
DBG: chan_10 <- OK
DBG: chan_10 -> GETATTR SERIALNO
DBG: chan_10 <- S SERIALNO D2760001240103040006123456780000
DBG: chan_10 <- OK
DBG: chan_10 -> READKEY OPENPGP.3
DBG: chan_10 <- [ 44 20 28 31 ...(83 byte(s) skipped) ]
DBG: chan_10 <- OK
DBG: chan_10 -> GETATTR $DISPSERIALNO
DBG: chan_10 <- S $DISPSERIALNO 000612345678
DBG: chan_10 <- OK
ssh request handler for request_identities (11) ready
ssh request handler for sign_request (13) started
DBG: chan_10 -> SERIALNO --demand=D2760001240103040006123456780000
DBG: chan_10 <- S SERIALNO D2760001240103040006123456780000
DBG: chan_10 <- OK
detected card with S/N D2760001240103040006123456780000
DBG: chan_10 -> SETDATA 3021...>
DBG: chan_10 <- OK
DBG: chan_10 -> PKAUTH D459...
scdaemon[898750]: app_auth failed: Invalid value
DBG: chan_10 <- ERR 100663351 Invalid value <SCD>
smartcard signing failed: Invalid value
ssh sign request failed: Invalid value <SCD>

When I tried a different server, things did work:

...
DBG: chan_10 -> SERIALNO --demand=D2760001240103040006114652250000
DBG: chan_10 <- S SERIALNO D2760001240103040006114652250000
DBG: chan_10 <- OK
detected card with S/N D2760001240103040006114652250000
DBG: chan_10 -> SETDATA 3021...>
DBG: chan_10 <- OK
DBG: chan_10 -> PKAUTH D459...
DBG: chan_10 <- [ 44 20 1d 30 ...(52 byte(s) skipped) ]
DBG: chan_10 <- OK

No explanations to be found here. But the different server did provide the clue that the OpenSSH version was involved.

I tried a few different OpenSSH versions:

trusty - 1:6.6p1-2ubuntu2.13 - Accepted publickey ... ED25519 de:14:...
bionic - 1:7.6p1-4ubuntu0.7  - Accepted publickey ... ED25519 SHA256:lKE...
focal  - 1:8.2p1-4ubuntu0.9  - Accepted publickey ... ED25519 SHA256:lKE...
jammy  - 1:8.9p1-3ubuntu0.6  - <failure>

And in fact (tested with a bit of SSH key forwarding) using an older client against the newer server also worked.

OpenSSH client side debugging started turning up interesting differences after the third -v:

-- OpenSSH_8.9p1 Ubuntu-3ubuntu0.6, OpenSSL 3.0.2 15 Mar 2022 --
-- debug1: Reading configuration data /home/walter/.ssh/config --
-- debug3: kex names ok: [diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1] --
...
1. debug1: Connecting to old_server port 22.
 2. debug1: Connecting to my_server port 22.
  3. debug1: Connecting to rsa_server port 22.
   4. debug1: Connecting to hostkey_server port 22.
-- debug3: set_sock_tos: set socket 3 IP_TOS 0x10 --
-- debug1: Connection established. --
...
-- debug1: Local version string SSH-2.0-OpenSSH_8.9p1 Ubuntu-3ubuntu0.6 --
1. debug1: Remote protocol version 2.0, remote software version OpenSSH_8.2p1 Ubuntu-4ubuntu0.9
 2. debug1: Remote protocol version 2.0, remote software version OpenSSH_8.9p1 Ubuntu-3ubuntu0.6
  3. debug1: Remote protocol version 2.0, remote software version OpenSSH_8.9p1 Ubuntu-3ubuntu0.6
   4. debug1: Remote protocol version 2.0, remote software version OpenSSH_8.9p1 Ubuntu-3ubuntu0.6
1. debug1: compat_banner: match: OpenSSH_8.2p1 Ubuntu-4ubuntu0.9 pat OpenSSH* compat 0x04000000
 2. debug1: compat_banner: match: OpenSSH_8.9p1 Ubuntu-3ubuntu0.6 pat OpenSSH* compat 0x04000000
  3. debug1: compat_banner: match: OpenSSH_8.9p1 Ubuntu-3ubuntu0.6 pat OpenSSH* compat 0x04000000
   4. debug1: compat_banner: match: OpenSSH_8.9p1 Ubuntu-3ubuntu0.6 pat OpenSSH* compat 0x04000000

Server 1 was an older server, server 2, 3 and 4 are the new server, with: (2) failure, (3) an RSA key, and (4) a forced ssh-ed25519 host key algorithm.

The log continues..

-- debug2: fd 3 setting O_NONBLOCK --
1. debug1: Authenticating to old_server:22 as 'walter'
 2. debug1: Authenticating to my_server:22 as 'walter'
  3. debug1: Authenticating to rsa_server:22 as 'walter'
   4. debug1: Authenticating to hostkey_server:22 as 'walter'
-- debug3: send packet: type 20 --
-- debug1: SSH2_MSG_KEXINIT sent --
-- debug3: receive packet: type 20 --
-- debug1: SSH2_MSG_KEXINIT received --
-- debug2: local client KEXINIT proposal --
1. debug2: KEX algorithms: curve25519-sha256,curve25519-sha256@libssh.org,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,sntrup761x25519-sha512@openssh.com,diffie-hellman-group-exchange-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512,diffie-hellman-group14-sha256,ext-info-c,kex-strict-c-v00@openssh.com
 2. debug2: KEX algorithms: curve25519-sha256,ext-info-c,kex-strict-c-v00@openssh.com
  3. debug2: KEX algorithms: curve25519-sha256,curve25519-sha256@libssh.org,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,sntrup761x25519-sha512@openssh.com,diffie-hellman-group-exchange-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512,diffie-hellman-group14-sha256,ext-info-c,kex-strict-c-v00@openssh.com
   4. debug2: KEX algorithms: curve25519-sha256,ext-info-c,kex-strict-c-v00@openssh.com
1. debug2: host key algorithms: ecdsa-sha2-nistp256
 2. debug2: host key algorithms: ecdsa-sha2-nistp256
  3. debug2: host key algorithms: ecdsa-sha2-nistp256
   4. debug2: host key algorithms: ssh-ed25519

The difference here is me explicitly setting the HostKeyAlgorithms=ssh-ed25519 for server 4.

Some more uninteresting logs..

-- debug2: ciphers ctos: chacha20-poly1305@openssh.com,aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm@openssh.com,aes256-gcm@openssh.com --
-- debug2: ciphers stoc: chacha20-poly1305@openssh.com,aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm@openssh.com,aes256-gcm@openssh.com --
-- debug2: MACs ctos: umac-64-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha1-etm@openssh.com,umac-64@openssh.com,umac-128@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1 --
-- debug2: MACs stoc: umac-64-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha1-etm@openssh.com,umac-64@openssh.com,umac-128@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1 --
-- debug2: compression ctos: none,zlib@openssh.com,zlib --
-- debug2: compression stoc: none,zlib@openssh.com,zlib --
-- debug2: languages ctos: --
-- debug2: languages stoc: --
-- debug2: first_kex_follows 0 --
-- debug2: reserved 0 --
-- debug2: peer server KEXINIT proposal --
1. debug2: KEX algorithms: curve25519-sha256,curve25519-sha256@libssh.org,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512,diffie-hellman-group14-sha256
 2. debug2: KEX algorithms: curve25519-sha256,curve25519-sha256@libssh.org,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,sntrup761x25519-sha512@openssh.com,diffie-hellman-group-exchange-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512,diffie-hellman-group14-sha256,kex-strict-s-v00@openssh.com
  3. debug2: KEX algorithms: curve25519-sha256,curve25519-sha256@libssh.org,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,sntrup761x25519-sha512@openssh.com,diffie-hellman-group-exchange-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512,diffie-hellman-group14-sha256,kex-strict-s-v00@openssh.com
   4. debug2: KEX algorithms: curve25519-sha256,curve25519-sha256@libssh.org,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,sntrup761x25519-sha512@openssh.com,diffie-hellman-group-exchange-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512,diffie-hellman-group14-sha256,kex-strict-s-v00@openssh.com
1. debug2: host key algorithms: rsa-sha2-512,rsa-sha2-256,ssh-rsa,ecdsa-sha2-nistp256,ssh-ed25519
 2. debug2: host key algorithms: rsa-sha2-512,rsa-sha2-256,ecdsa-sha2-nistp256,ssh-ed25519
  3. debug2: host key algorithms: rsa-sha2-512,rsa-sha2-256,ecdsa-sha2-nistp256,ssh-ed25519
   4. debug2: host key algorithms: rsa-sha2-512,rsa-sha2-256,ecdsa-sha2-nistp256,ssh-ed25519
-- debug2: ciphers ctos: chacha20-poly1305@openssh.com,aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm@openssh.com,aes256-gcm@openssh.com --
-- debug2: ciphers stoc: chacha20-poly1305@openssh.com,aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm@openssh.com,aes256-gcm@openssh.com --
-- debug2: MACs ctos: umac-64-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha1-etm@openssh.com,umac-64@openssh.com,umac-128@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1 --
-- debug2: MACs stoc: umac-64-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha1-etm@openssh.com,umac-64@openssh.com,umac-128@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1 --
-- debug2: compression ctos: none,zlib@openssh.com --
-- debug2: compression stoc: none,zlib@openssh.com --
-- debug2: languages ctos: --
-- debug2: languages stoc: --
-- debug2: first_kex_follows 0 --
-- debug2: reserved 0 --
1. 
 2. debug3: kex_choose_conf: will use strict KEX ordering
  3. debug3: kex_choose_conf: will use strict KEX ordering
   4. debug3: kex_choose_conf: will use strict KEX ordering

This could be something. will use strict KEX ordering is only seen on the newer servers.

-- debug1: kex: algorithm: curve25519-sha256 --
1. debug1: kex: host key algorithm: ecdsa-sha2-nistp256
 2. debug1: kex: host key algorithm: ecdsa-sha2-nistp256
  3. debug1: kex: host key algorithm: ecdsa-sha2-nistp256
   4. debug1: kex: host key algorithm: ssh-ed25519
-- debug1: kex: server->client cipher: chacha20-poly1305@openssh.com MAC: <implicit> compression: none --
-- debug1: kex: client->server cipher: chacha20-poly1305@openssh.com MAC: <implicit> compression: none --
-- debug3: send packet: type 30 --
-- debug1: expecting SSH2_MSG_KEX_ECDH_REPLY --
-- debug3: receive packet: type 31 --
-- debug1: SSH2_MSG_KEX_ECDH_REPLY received --
1. debug1: Server host key: ecdsa-sha2-nistp256 SHA256:abc...
 2. debug1: Server host key: ecdsa-sha2-nistp256 SHA256:abc...
  3. debug1: Server host key: ecdsa-sha2-nistp256 SHA256:abc...
   4. debug1: Server host key: ssh-ed25519 SHA256:def...
1. debug3: record_hostkey: found key type ECDSA in file /home/walter/.ssh/known_hosts:1234
 2. debug3: record_hostkey: found key type ECDSA in file /home/walter/.ssh/known_hosts:1234
  3. debug3: record_hostkey: found key type ECDSA in file /home/walter/.ssh/known_hosts:1234
   4. debug3: record_hostkey: found key type ED25519 in file /home/walter/.ssh/known_hosts:1234
1. debug3: load_hostkeys_file: loaded 1 keys from old_server
 2. debug3: load_hostkeys_file: loaded 1 keys from my_server
  3. debug3: load_hostkeys_file: loaded 1 keys from rsa_server
   4. debug3: load_hostkeys_file: loaded 1 keys from hostkey_server
1. debug1: Host 'old_server' is known and matches the ECDSA host key.
 2. debug1: Host 'my_server' is known and matches the ECDSA host key.
  3. debug1: Host 'rsa_server' is known and matches the ECDSA host key.
   4. debug1: Host 'hostkey_server' is known and matches the ED25519 host key.
-- debug1: Found key in /home/walter/.ssh/known_hosts:1235
-- debug3: send packet: type 21 --
1. 
 2. debug1: ssh_packet_send2_wrapped: resetting send seqnr 3
  3. debug1: ssh_packet_send2_wrapped: resetting send seqnr 3
   4. debug1: ssh_packet_send2_wrapped: resetting send seqnr 3
-- debug2: ssh_set_newkeys: mode 1 --
-- debug1: rekey out after 134217728 blocks --
-- debug1: SSH2_MSG_NEWKEYS sent --
-- debug1: expecting SSH2_MSG_NEWKEYS --
-- debug3: receive packet: type 21 --
1. 
 2. debug1: ssh_packet_read_poll2: resetting read seqnr 3
  3. debug1: ssh_packet_read_poll2: resetting read seqnr 3
   4. debug1: ssh_packet_read_poll2: resetting read seqnr 3

The ssh_packet_send2_wrapped and ssh_packet_read_poll2 is also new.

-- debug1: SSH2_MSG_NEWKEYS received --
-- debug2: ssh_set_newkeys: mode 0 --
-- debug1: rekey in after 134217728 blocks --
-- debug2: get_agent_identities: ssh_agent_bind_hostkey: agent refused operation --
-- debug1: get_agent_identities: agent returned 3 keys --
1. debug1: Will attempt key: cardno:000612345678 ED25519 SHA256:lKE... agent
 2. debug1: Will attempt key: cardno:000612345678 ED25519 SHA256:lKE... agent
  3. debug1: Will attempt key: cardno:000611111111 RSA SHA256:vYJ... agent
   4. debug1: Will attempt key: cardno:000612345678 ED25519 SHA256:lKE... agent

The RSA key is obviously different...

-- debug2: pubkey_prepare: done --
-- debug3: send packet: type 5 --
-- debug3: receive packet: type 7 --
-- debug1: SSH2_MSG_EXT_INFO received --
1. debug1: kex_input_ext_info: server-sig-algs=<ssh-ed25519,sk-ssh-ed25519@openssh.com,ssh-rsa,rsa-sha2-256,rsa-sha2-512,ssh-dss,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,sk-ecdsa-sha2-nistp256@openssh.com>
 2. debug1: kex_input_ext_info: server-sig-algs=<ssh-ed25519,sk-ssh-ed25519@openssh.com,ssh-rsa,rsa-sha2-256,rsa-sha2-512,ssh-dss,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,sk-ecdsa-sha2-nistp256@openssh.com,webauthn-sk-ecdsa-sha2-nistp256@openssh.com>
  3. debug1: kex_input_ext_info: server-sig-algs=<ssh-ed25519,sk-ssh-ed25519@openssh.com,ssh-rsa,rsa-sha2-256,rsa-sha2-512,ssh-dss,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,sk-ecdsa-sha2-nistp256@openssh.com,webauthn-sk-ecdsa-sha2-nistp256@openssh.com>
   4. debug1: kex_input_ext_info: server-sig-algs=<ssh-ed25519,sk-ssh-ed25519@openssh.com,ssh-rsa,rsa-sha2-256,rsa-sha2-512,ssh-dss,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,sk-ecdsa-sha2-nistp256@openssh.com,webauthn-sk-ecdsa-sha2-nistp256@openssh.com>

Extra server signature algorithms shouldn't matter.

1. 
 2. debug1: kex_input_ext_info: publickey-hostbound@openssh.com=<0>
  3. debug1: kex_input_ext_info: publickey-hostbound@openssh.com=<0>
   4. debug1: kex_input_ext_info: publickey-hostbound@openssh.com=<0>

kex_input_ext_info: publickey-hostbound@openssh.com is also new...

-- debug3: receive packet: type 6 --
-- debug2: service_accept: ssh-userauth --
-- debug1: SSH2_MSG_SERVICE_ACCEPT received --
-- debug3: send packet: type 50 --
-- debug3: receive packet: type 51 --
-- debug1: Authentications that can continue: publickey --
-- debug3: start over, passed a different list publickey --
-- debug3: preferred gssapi-with-mic,publickey,keyboard-interactive,password --
-- debug3: authmethod_lookup publickey --
-- debug3: remaining preferred: keyboard-interactive,password --
-- debug3: authmethod_is_enabled publickey --
-- debug1: Next authentication method: publickey --
1. debug1: Offering public key: cardno:000612345678 ED25519 SHA256:lKE... agent
 2. debug1: Offering public key: cardno:000612345678 ED25519 SHA256:lKE... agent
  3. debug1: Offering public key: cardno:000604261342 RSA SHA256:vYJ... agent
   4. debug1: Offering public key: cardno:000612345678 ED25519 SHA256:lKE... agent
-- debug3: send packet: type 50 --
-- debug2: we sent a publickey packet, wait for reply --
-- debug3: receive packet: type 60 --
1. debug1: Server accepts key: cardno:000612345678 ED25519 SHA256:lKE... agent
 2. debug1: Server accepts key: cardno:000612345678 ED25519 SHA256:lKE... agent
  3. debug1: Server accepts key: cardno:000604261342 RSA SHA256:vYJ... agent
   4. debug1: Server accepts key: cardno:000612345678 ED25519 SHA256:lKE... agent
1. debug3: sign_and_send_pubkey: using publickey with ED25519 SHA256:lKE...
 2. debug3: sign_and_send_pubkey: using publickey-hostbound-v00@openssh.com with ED25519 SHA256:lKE...
  3. debug3: sign_and_send_pubkey: using publickey-hostbound-v00@openssh.com with RSA SHA256:vYJ...
   4. debug3: sign_and_send_pubkey: using publickey-hostbound-v00@openssh.com with ED25519 SHA256:lKE...
1. debug3: sign_and_send_pubkey: signing using ssh-ed25519 SHA256:lKE...
 2. debug3: sign_and_send_pubkey: signing using ssh-ed25519 SHA256:lKE...
  3. debug3: sign_and_send_pubkey: signing using rsa-sha2-512 SHA256:vYJ...
   4. debug3: sign_and_send_pubkey: signing using ssh-ed25519 SHA256:lKE...
1. 
 2. sign_and_send_pubkey: signing failed for ED25519 "cardno:000612345678" from agent: agent refused operation
  3.
   4.
...
1. Authenticated to old_server:22 using "publickey".
 2. debug1: No more authentication methods to try.
  3. Authenticated to walter-dev.osso.nl ([217.21.199.35]:22) using "publickey".
   4. Authenticated to hostkey_server:22 using "publickey".

Here we saw that:

  • Connecting to the old server succeeded with the ED25519 key.
  • Connecting to the new server failed with the ED25519 key.
  • Connecting to the new server succeeded with an RSA key.
  • Connecting to the new server succeeded with HostKeyAlgorithms set to ED25519.

The culprit looks like publickey-hostbound-v00@openssh.com. According to SSH agent restriction documentation, this option passes the destination to the client, where it should be validated and approved.

If either the client or the server doesn't support this extension, things work just fine. But if they both do, then the gpg-agent fails to properly sign the public key negotiation data.

Destination restrictions in ssh-agent strongly depend on the agent being able to parse the data being signed, and the contents having all the information needed to compare against the restrictions listed for a given key. SSH user authentication requests have a format that meets these requirements, but other uses of the agent protocol are not likely to.

For now, my guess is that indeed gpg-agent does not support the extra hostname from the extension. The workaround is either:

  • Set -oHostKeyAlgorithms=ssh-ed25519 or
  • set -oPubkeyAuthentication=unbound on the client.

I don't know why the first option works, but it does. The second one should disable the publickey-hostbound-v00@openssh.com extension, making negotiation fall back to the original behaviour. So, if you're affected by this, it may make sense to add that to your ~/.ssh/config.

The relevant ticket for GnuPG is OpenSSH 8.9, 9.0, and 9.1 can't authenticate with gpg-agent and usb token.