I know that you have resolved this issue already, but I thought I would add what I think to be the most effective way to troubleshoot the rsync connection to Greenbone’s feed sync servers in case someone else has this issue.
The nping command is part of the nmap tool. It can be used to directly traceroute a TCP connection to a specific port while traceroute and tcptraceroute cannot be configured to test a specific port. This will help identify port-based firewall rules as well as host / IP-based firewall rules.
sudo nping --tcp --traceroute -c 13 -p 873 feed.community.greenbone.net
** Note: nping --tcp command requires sudo or root.
The output here:
Starting Nping 0.7.80 ( https://nmap.org/nping ) at 2023-06-28 13:48 EDT
SENT (0.0274s) TCP 192.168.2.251:1323 > 45.135.106.143:873 S ttl=1 id=37878 iplen=40 seq=2348950242 win=1480
RCVD (0.0280s) ICMP [192.168.2.1 > 192.168.2.251 TTL=0 during transit (type=11/code=0) ] IP [ttl=64 id=43189 iplen=68 ]
SENT (1.0281s) TCP 192.168.2.251:1323 > 45.135.106.143:873 S ttl=2 id=37878 iplen=40 seq=2348950242 win=1480
RCVD (1.0296s) ICMP [64.230.11.215 > 192.168.2.251 TTL=0 during transit (type=11/code=0) ] IP [ttl=254 id=0 iplen=56 ]
SENT (2.0300s) TCP 192.168.2.251:1323 > 45.135.106.143:873 S ttl=3 id=37878 iplen=40 seq=2348950242 win=1480
RCVD (2.0452s) ICMP [64.230.97.188 > 192.168.2.251 TTL=0 during transit (type=11/code=0) ] IP [ttl=244 id=0 iplen=168 ]
SENT (3.0315s) TCP 192.168.2.251:1323 > 45.135.106.143:873 S ttl=4 id=37878 iplen=40 seq=2348950242 win=1480
RCVD (3.0468s) ICMP [64.230.51.151 > 192.168.2.251 TTL=0 during transit (type=11/code=0) ] IP [ttl=246 id=19613 iplen=168 ]
SENT (4.0330s) TCP 192.168.2.251:1323 > 45.135.106.143:873 S ttl=5 id=37878 iplen=40 seq=2348950242 win=1480
SENT (5.0344s) TCP 192.168.2.251:1323 > 45.135.106.143:873 S ttl=6 id=37878 iplen=40 seq=2348950242 win=1480
SENT (6.0358s) TCP 192.168.2.251:1323 > 45.135.106.143:873 S ttl=7 id=37878 iplen=40 seq=2348950242 win=1480
RCVD (6.0539s) ICMP [64.230.79.73 > 192.168.2.251 TTL=0 during transit (type=11/code=0) ] IP [ttl=249 id=0 iplen=56 ]
SENT (7.0379s) TCP 192.168.2.251:1323 > 45.135.106.143:873 S ttl=8 id=37878 iplen=40 seq=2348950242 win=1480
SENT (8.0392s) TCP 192.168.2.251:1323 > 45.135.106.143:873 S ttl=9 id=37878 iplen=40 seq=2348950242 win=1480
RCVD (8.1506s) ICMP [4.69.163.106 > 192.168.2.251 TTL=0 during transit (type=11/code=0) ] IP [ttl=240 id=0 iplen=56 ]
SENT (9.0398s) TCP 192.168.2.251:1323 > 45.135.106.143:873 S ttl=10 id=37878 iplen=40 seq=2348950242 win=1480
RCVD (9.1496s) ICMP [62.67.19.26 > 192.168.2.251 TTL=0 during transit (type=11/code=0) ] IP [ttl=54 id=1090 iplen=72 ]
SENT (10.0407s) TCP 192.168.2.251:1323 > 45.135.106.143:873 S ttl=11 id=37878 iplen=40 seq=2348950242 win=1480
RCVD (10.1505s) ICMP [195.34.175.194 > 192.168.2.251 TTL=0 during transit (type=11/code=0) ] IP [ttl=241 id=0 iplen=56 ]
SENT (11.0417s) TCP 192.168.2.251:1323 > 45.135.106.143:873 S ttl=12 id=37878 iplen=40 seq=2348950242 win=1480
SENT (12.0431s) TCP 192.168.2.251:1323 > 45.135.106.143:873 S ttl=13 id=37878 iplen=40 seq=2348950242 win=1480
Max rtt: 111.280ms | Min rtt: 0.551ms | Avg rtt: 47.643ms
Raw packets sent: 13 (520B) | Rcvd: 8 (700B) | Lost: 5 (38.46%)
Nping done: 1 IP address pinged in 13.07 seconds
If there is something wrong with this solution let me know.